Version May 2024
INTRODUCTION — The skin biopsy is a relatively simple and minimally invasive diagnostic procedure that is essential in the management of skin disorders [1]. Common skin biopsy procedures are reviewed here. Biopsy of the nail apparatus is discussed separately. The elliptical excision technique, Mohs surgery, and the prevention and treatment of skin surgery complications are also discussed separately.
●(See "Nail biopsy: Indications and techniques".)
●(See "Fusiform/elliptical excision".)
●(See "Mohs surgery".)
●(See "Skin surgery: Prevention and treatment of complications".)
INDICATIONS — Biopsy is indicated in the following circumstances (table 1) [2-5]:
●Suspected neoplastic lesions
●Bullous disorders
●Hair disorders
●To confirm a clinical diagnosis
●Atypical presentation of a skin lesion/eruption
●Skin lesion/eruption for which the clinical differential diagnosis is broad
●To obtain tissue samples for microbiologic cultures
●To evaluate unexpected poor response to therapy
●To evaluate skin symptoms in the absence of findings
Biopsy is primarily performed to establish a diagnosis, but occasionally, it can also serve as the definitive treatment for irritated; inflamed; precancerous; or small, malignant lesions [2,3,6]. However, for malignant lesions, a pathologic report indicating that the biopsy margins are "clear" does not necessarily mean that there has been adequate therapy. Re-excision may be needed for appropriate surgical management.
Skin biopsy also has an emerging role in the diagnosis of disorders of the peripheral nervous system, including progressive myoclonic epilepsy, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), small fiber neuropathies, and neuroaxonal dystrophy, even in the absence of visible skin changes. (See "Evaluation of peripheral nerve and muscle disease", section on 'Skin biopsy' and "Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)", section on 'Skin biopsy' and "Skin biopsy for the evaluation of peripheral nerve disease".)
CONTRAINDICATIONS — There are few absolute contraindications to skin biopsy. It should not usually be performed at an infected site, although occasionally, infection is the indication for the procedure.
PREPROCEDURE CONSIDERATIONS — Prior to proceeding to a skin biopsy, patients should be asked about allergies to topical antibiotics, antiseptics, local anesthetics, and reactions to tape. Inquiries should also be made regarding bleeding disorders, bleeding with previous surgery, and use of anticoagulants or antiplatelet agents. (See "Preoperative assessment of bleeding risk".)
Excessive bleeding is rarely a problem in patients taking oral anticoagulants or antiplatelet agents. Patients taking aspirin can generally be managed with careful attention to hemostasis and the use of a pressure dressing (see 'Complications' below). These medications should generally not be discontinued for simple skin biopsies. Consider referring patients on anticoagulants or antiplatelet agents to a dermatologist or surgeon for biopsies. (See "Skin surgery: Prevention and treatment of complications", section on 'Patients on anticoagulants and antiplatelet agents'.)
For patients with bleeding disorders, we suggest referral to a dermatologist or surgeon for skin biopsies. Similar careful consideration is warranted in patients with severe thrombocytopenia or hematologic malignancies.
Universal precautions should be observed by wearing gloves and eye guards.
PREPROCEDURE CONSIDERATIONS IN CHILDREN — Skin biopsy in pediatric patients provides unique challenges. Rates of needle phobia in children may be as high as 60 percent [7]. Understanding the child's prior experiences with medical care is essential to accomplishing the procedure and minimizing anxiety for the patient and parent/caregiver. Other interventions, such as vibratory devices and distraction, may help to decrease pain and anxiety (see "Subcutaneous infiltration of local anesthetics", section on 'Methods to decrease injection pain') [8,9]. We avoid promising any child that a procedure will be "pain free."
Though injection of lidocaine or other local anesthesia is essential for adequate procedural pain control, additional use of topical preparations (eg, lidocaine-prilocaine cream [eutectic mixture of local anesthetics]) can be offered prior to the procedure to decrease pain. Additional recommendations on minimizing pain with injection of lidocaine are discussed below. (See 'Anesthesia' below.)
Clinicians should be aware of the maximum allowable doses for topical anesthesia in infants and children as well as the maximum dose of intralesional lidocaine or lidocaine-epinephrine based on the child's weight. (See "Clinical use of topical anesthetics in children", section on 'Agents for intact skin' and "Subcutaneous infiltration of local anesthetics".)
Child life specialists, when available, should be utilized for biopsy in children.
●Infants – Skin biopsy procedures in infants are otherwise similar to adults, though with the consideration that the infant subcutis may be thinner than in older children or adults. Avoid dressings that could be dislodged and become a choking hazard for the infant. Clinicians with expertise in pediatric dermatology should be involved in skin biopsy of premature infants.
●Toddlers and young children – Most young children will not be able to reason and understand the importance of the procedure. Clinicians should discuss with the parent/guardian options to hold young children safely. Biopsy of some body sites (eg, periocular skin) may not be completed safely in an awake child. Additional sedation with the assistance of a pediatric anesthesiologist may be discussed if a biopsy is essential to patient care. Care should be taken to complete the procedure as quickly as possible, with all medications, instruments, and dressings ready for immediate use. When possible, we find that having a parent/guardian present and holding and comforting the child to be helpful, with additional staff members assisting to ensure the child is still for the duration of the procedure. Some parents/guardians may not feel comfortable participating in this way. Use of distraction and/or vibration devices may improve tolerability of the procedure.
●Older children and teenagers – Depending on the developmental stage of the child, an age-appropriate explanation of the biopsy procedure should be undertaken with older children and teenagers along with consent from the parent/guardian. There is considerable variation in the ability of older children to understand and tolerate painful medical procedures, though techniques involving distraction and vibratory devices can be helpful in most cases. Older children or children with developmental disabilities who are unable to sit still often cannot be safely restrained for a biopsy and may require a sedated procedure if a biopsy is medically essential. (See "Procedural sedation in children: Approach" and "Anesthesia for the child with autism".)
SITE SELECTION — Site selection can be critical to diagnosis. The appropriate biopsy site depends upon the type and location of lesion or eruption. The location of biopsy within a particular lesion also depends upon the type and size of the lesion. The clinician should identify unadulterated primary lesions for biopsy. Older lesions with secondary changes, such as crusts, fissures, erosions, excoriations, and ulcerations, should be avoided since the primary pathologic process may be obscured. Multiple sites may be biopsied if the differential diagnosis is broad to minimize sampling error.
●Inflammatory lesions – For inflammatory lesions, those with characteristic acute, inflammatory changes (eg, erythema) should be biopsied first. Evolutionary changes may take time, so biopsies performed too early and very late lesions may reveal only nonspecific or secondary features [2,5,10-12].
●Vesicobullous lesions – For blistering diseases, early evolving lesions have more specific histopathology and are preferred for biopsy. Only the newest vesicles and blisters should be biopsied (ideally within 48 hours of their appearance). The specimen should include intact epidermis (normal-appearing skin adjacent to the blister) for examination of the dermal-epidermal junction. (See "Approach to the patient with cutaneous blisters", section on 'Skin biopsy'.)
•Vesicles – When vesicles are biopsied, remove vesicles intact (when possible) with adjacent normal-appearing skin. Disruption makes histologic interpretation more difficult.
•Bullae – Bullae should be biopsied at the edge to include a small part of the blister with adjacent intact skin, keeping the blister roof attached. This technique is important for diagnosis; it allows the pathologist to determine the level of blister formation within the skin (eg, subcorneal, intraepidermal, subepidermal).
●Nonbullous lesions – For nonbullous lesions, the biopsy should include maximal lesional skin and minimal normal skin. For lesions between 1 and 4 mm in diameter, biopsy the center or excise the entire lesion. For large primary lesions, biopsy the edge, the thickest portion, or the area that is most abnormal in color or texture. These sites will most likely contain the distinctive pathology.
●Lesions on cosmetically sensitive areas – Cosmetically sensitive areas, such as the face, should be avoided, if possible, when choosing a biopsy site for a generalized process. When there are individual suspicious lesions involving the face or other cosmetically important areas, it may be preferable to refer the patient to a dermatologist or plastic surgeon with expertise in operating in such areas.
●Poor healing areas – Areas with poor healing characteristics, such as distal lower extremities, should be avoided if possible.
SITE IDENTIFICATION — It is important to identify the biopsy site before performing the definitive surgical treatment to avoid wrong site surgery [13]. Several methods have been used for the identification of the biopsy site, including recording in medical records an accurate description of the lesion and surrounding anatomic landmarks and/or measurements from at least two fixed landmarks, marking the site with tattoo ink, and taking a photograph of the biopsy site. There is consensus among experts that taking a high-quality photograph of the lesion that includes one or more visible anatomic landmarks at the time of biopsy provides a quick and unequivocal documentation of the biopsy site [14]. A photograph on the patient's cell phone can be easily transported to a surgeon for treatment if required. (See "Skin surgery: Prevention and treatment of complications", section on 'Preventing wrong site surgery'.)
BIOPSY SITE PREPARATION
Antisepsis — Office-based dermatologic procedures are performed under varying degrees of antisepsis.
●Clean technique – Clean technique involves good hand hygiene, clean gloves, efforts to prevent contamination, and routine cleaning of the site [15]. Shave and punch biopsies typically use clean, not sterile, technique. Mask, gown, and sterile gloves are not necessary.
●Aseptic technique – Aseptic technique involves maintaining an environment that prevents infection and use of sterile attire, sterile equipment, antiseptic skin preparations, and environmental controls [15]. Mask, gown, and sterile gloves are indicated for excisional biopsies and are reasonable for any patient at increased risk of infection [11].
Several studies and a systematic review and meta-analysis have shown no significant difference in infection rates between sterile and clean gloves for simple outpatient dermatologic procedures [16-18].
Preparing the patient — The patient should be provided with all information necessary to obtain an informed consent. This typically includes the nature of the condition, goals of the biopsy, risks, benefits, and alternatives to the procedure, including the option to refuse. (See "Informed procedural consent".)
To ensure patient safety, the patient should be placed in a recumbent position in the event of a vasovagal reaction.
Preparing the site — Any common skin antiseptic, such as isopropyl alcohol, povidone iodine, or chlorhexidine gluconate, can be used to prepare the biopsy site [3,10,11]. Mark the intended lesion with a surgical marker since it may be temporarily obliterated following injection of the anesthetic. Marking the outlines for excisional biopsies can also be helpful. For excisions, place a fenestrated surgical drape over the biopsy site after the area is cleansed and anesthetized.
Round wounds tend to be pulled open along the direction of skin tension lines, known as Langer lines [19-21]. Surgical incisions placed parallel to tension lines will close more easily and cosmetically than those placed at right angles [6,19-21].
The tension lines can be demonstrated by gently compressing relaxed skin with the thumb and index finger (picture 1); on the face, wrinkle lines are another good indicator. On the lower extremities, the biopsy ellipse should be parallel to the long axis of the extremity and not transverse.
Anesthesia — The most commonly used local anesthetic is 1% or 2% lidocaine. The combination of lidocaine-epinephrine (eg, lidocaine hydrochloride 1% or 2% and epinephrine 1:100,000 or 1:200,000) has several advantages over lidocaine alone: blood vessel constriction, decreased bleeding, prolonged anesthesia, and reduced lidocaine toxicity [3,22]. The onset of vasoconstriction is approximately 10 minutes slower than that of anesthesia. The maximum dose for children and adults is 7 mg/kg.
Given the vasoconstrictive properties of epinephrine, concern has been raised regarding the possibility of epinephrine-induced ischemic necrosis in areas such as the digits, ears, and nose [6,19,22]. However, the results of some studies suggest that with proper technique, local infiltrative anesthesia with diluted solutions of lidocaine-epinephrine may be safe for use in these areas [23-26].
The following techniques can minimize the sting of injection [3,10,20] (see "Subcutaneous infiltration of local anesthetics", section on 'Methods to decrease injection pain'):
●Mixing 1 mL of sodium bicarbonate 1 mEq/mL with 9 mL of lidocaine.
●Using a 30-gauge needle and slow injection rate.
●Making the initial injection perpendicular (or near perpendicular) to the skin; deep injections sting less than superficial injections but prolong the time to adequate anesthesia [27].
●Using small syringes (1 and 3 mL) permits easier injections and are less cumbersome to handle.
●Application of topical lidocaine or lidocaine-prilocaine prior to injection.
The anesthetic can be injected directly into or immediately adjacent to small lesions. The anesthetic must be infiltrated into the dermis if it is being used to elevate a lesion for biopsy. A field block should be performed for larger lesions by placing a ring of anesthetic around the surgical site, advancing and injecting through a site that has been previously anesthetized [20,28]. (See "Subcutaneous infiltration of local anesthetics", section on 'Direct infiltration' and "Subcutaneous infiltration of local anesthetics", section on 'Field block'.)
BIOPSY TECHNIQUES
Equipment — A list of the necessary supplies and instruments is shown in the table (table 2). Not all of the supplies will be needed for every biopsy.
Shave biopsy — Shave biopsies can be done in a short amount of time, require minimal training, and do not require sutures for closure. A small, depressed scar approximately the size of the initial lesion is likely to occur [29]. Lesions that are most suitable for shave biopsies are either elevated above the skin surface or are confined to the epidermis [3,11,20,29]. Examples include seborrheic or actinic keratoses, skin tags, warts, and superficial basal cell or squamous cell carcinomas.
●Tools – A number 15 blade on a scalpel or a razor blade can be used for shave biopsy (picture 2). Devices that provide a holder or handle for the razor blade are commercially available, and many clinicians find these helpful. The razor blade technique has several advantages:
•The razor is sharper than most surgical blades.
•The razor can be bent concave or convex with the thumb and forefinger to better conform to the surface being cut.
•Depth is easily controlled by increasing or decreasing the convexity of the curve.
Curved scissors are an efficient means of removing skin tags and other small, exophytic growths [3]. The lesion to be removed is stabilized with toothed forceps, then cut at the base.
●Techniques – Shave biopsies can be either superficial or deep (figure 1).
•Superficial shave biopsy – Superficial shave biopsies are done across or nearly parallel to the skin surface and extend into the epidermis only or epidermis and limited superficial dermis (figure 1). Superficial shave biopsies should not be used for pigmented lesions; a partial biopsy of an unsuspected melanoma does not allow proper staging and may interfere with initial surgical management decisions [2,3,11,30]. (See 'Biopsy of pigmented lesions' below.)
The shave biopsy can be facilitated by raising the lesion with a wheal of injected anesthetic, allowing the lesion to be propped up and stabilized between the thumb and forefinger (figure 2) [6,19,29].
When performing a superficial shave biopsy, a number 15 blade on a scalpel or a handheld razor blade is held tangential to the skin surface. The lesion is then excised with a forward, smooth, sweeping stroke of the blade going just under and across the lesion (figure 2).
•Deep shave biopsy (saucerization) – The deeper shave biopsy allows for sampling of the dermis and epidermis (figure 1), which is important for assessing basal cell and squamous cell carcinomas (superficial shave biopsies of exophytic tumors may only contain epidermal tissue, preventing histologic differentiation between in situ and invasive malignancy). For this biopsy, the clinician holds the scalpel like a pencil; makes a small, vertical incision into the skin with the beveled tip of the number 15 scalpel blade; then turns the scalpel and moves the blade forward in a horizontal, sawing motion, turning the blade up towards the surface to finish the excision [31]. A similar technique can be accomplished with a razor blade. The defect created is that of a saucer (hence the alternative name "saucerization" biopsy).
●Hemostasis – Bleeding following small shave biopsies can often be controlled with pressure alone. Persistent oozing may be stopped with 10% to 20% aluminum chloride in absolute alcohol (eg, aluminum chloride hexahydrate). Other hemostatic agents, in order of increasing corrosiveness, are Monsel solution (ferric subsulfate), trichloroacetic acid, and silver nitrate [32]. Monsel solution is more effective than aluminum chloride but also causes more tissue destruction and, like silver nitrate, can result in skin pigmentation (permanent tattoos). Waiting 10 minutes following infiltration of the lidocaine solution containing epinephrine will minimize the bleeding that must be controlled.
The wound must be as dry as possible for hemostatic agents to be effective. The agent is applied with a cotton applicator using firm pressure with a twisting motion [20]. Excellent hemostasis generally can be achieved in patients with bleeding disorders or in those taking anticoagulants or antiplatelet agents with the combined use of aluminum chloride and several minutes of direct pressure over the wound. Hemostasis with electrocautery should be considered for biopsy of lesions with a tendency for brisk bleeding, such as pyogenic granulomas.
Punch biopsy — Punch biopsies are performed with round, disposable knives ranging in diameter from 2 to 10 mm. Three millimeters is the smallest size likely to give sufficient tissue for consistently accurate histologic diagnosis [33]. The punch is an ideal procedure for diagnostic skin biopsy or removing small lesions. It often provides a better cosmetic result than a shave biopsy [10,11,29]. Punch biopsies are easily mastered by most practitioners; are quick; and have a low incidence of infection, bleeding, nonhealing, or significant scarring [10,11,29].
Biopsies for conditions expected to involve the deeper subcutaneous tissues, such as systemic amyloidosis [34], medium vessel vasculitis [35], or panniculitis [36], should extend into the subcutaneous fat. They may require a larger diameter punch, an excisional/incisional biopsy, or a telescoping approach involving use of a larger punch, followed by a smaller punch into the subcutis to obtain an adequate sample [37].
The specimen provided by a punch biopsy is a cone-shaped core of tissue with its widest diameter at the skin surface and narrowest at the biopsy base. The direction of the skin tension lines at the biopsy site should be determined prior to performing a punch biopsy.
●Technique
•Raise an intradermal welt (wheal) with the anesthetic and select the appropriate size punch.
•Stabilize the skin with the thumb and forefinger, stretching it slightly perpendicular to the normal skin tension lines. This will produce an oval (rather than round) wound, facilitating closure [2,3,6].
•Place the punch perpendicular to the skin and apply firm and constant downward pressure with a circular, twisting motion (picture 3). Avoid removing the punch to "check the progress." This may result in a ragged wound and a shredded biopsy sample [20,29].
•A definite "give" occurs when the punch reaches the subcutaneous fat, indicating that a full-thickness cut has been made.
•Remove the punch and apply downward finger pressure at the sides of the wound to pop up the core.
•Completely elevate the core with gentle use of forceps or a needle tip and excise it at its base with small tissue scissors. Apply pressure to the wound with gauze in preparation for closure.
•Punch biopsies of the scalp for diagnosis of hair disorders are best accomplished using a 4 mm punch and holding it at 20 degrees to the surface of the scalp, roughly along the axis of the hair follicle [11,38]. (See "Evaluation and diagnosis of hair loss", section on 'Scalp biopsies'.)
Biopsies of scalp lesions suspected of being malignant are performed in the same manner as other punch biopsies, with the punch perpendicular to the skin surface. Scalp biopsies bleed profusely and usually require the presence of an assistant [38].
●Hemostasis – Bleeding can be controlled with simple pressure on the wound in most cases [2]. If this is not successful after five minutes, a single suture may be sufficient. If bleeding remains uncontrolled, add one to two additional sutures to create a tamponade of the underlying vessel. It is very difficult to ligate the actual vessel within the small confines of a punch biopsy hole. Waiting 10 minutes following infiltration of the lidocaine solution containing epinephrine prior to performing the biopsy will also minimize the subsequent bleeding that must be controlled.
●Closure – Punch biopsies can be closed with sutures or allowed to heal by secondary intention. However, punches greater than 3 mm may produce unacceptable scarring and are best closed with one or two sutures. A randomized trial in volunteers found that the results with secondary intention healing after 4 mm punch biopsies were at least as good as with suturing but that patients preferred the appearance of 8 mm punch biopsies that were sutured [39]. Wounds that are allowed to heal by secondary intention may be treated with a hemostatic agent, such as aluminum chloride or absorbable gelatin.
Excisional biopsy — Excisional biopsy is performed for lesions that require complete removal for diagnostic or therapeutic purposes and for lesions that cannot be adequately biopsied with a punch due to size, depth, or location. Excisional biopsy allows for histopathologic examination of the entire lesion. Another advantage of an excisional biopsy is the amount of tissue that can be excised, allowing for multiple studies (culture, histopathology, immunofluorescence, electron microscopy) from one biopsy site [10,11]. Excisions are especially well suited for removal of skin tumors or for sampling inflammatory disorders that involve the subcutaneous fat.
Excisions require the greatest amount of expertise and time, generally require sutures, and are more easily performed with an assistant [10,11]. We recommend that clinicians receive appropriate training before attempting an excisional biopsy or refer patients requiring an excision to a qualified dermatologist or surgeon.
The excisional biopsy should be oriented so that it parallels or lies within the skin tension lines, along the axis of greatest laxity (picture 1) to produce the least noticeable linear scar. On the extremities, the excision should be oriented along the extremity's longitudinal axis.
The design and execution of the elliptical or diamond-shaped (rhombic) excision is reviewed in greater detail elsewhere. (See "Fusiform/elliptical excision", section on 'Design of the fusiform ellipse' and "Fusiform/elliptical excision", section on 'Execution of the fusiform ellipse'.)
Biopsy of pigmented lesions — The possibility of malignant melanoma must always be considered when removing pigmented lesions. For lesions suspicious for melanoma, the preferred technique is excisional biopsy that includes a 1 to 3 mm clinical margin [40]. (See 'Excisional biopsy' above and "Melanoma: Clinical features and diagnosis", section on 'Biopsy'.)
Small, pigmented lesions (<4 mm in diameter) can be biopsied using the punch excision technique, provided that the entire lesion is removed with the punch. Elevated, nodular lesions should be biopsied by elliptical excision whenever possible.
Deep shave or saucerization biopsies of the entire lesion that extend well into the deep reticular dermis may be performed when excisions are not possible or practical [41]. This technique is appropriate for flat and large lesions and should be performed by clinicians with appropriate training and expertise; referral to a dermatologist or surgeon is preferred [40,42,43]. As with elliptical excisional biopsies, the initial specimen should include the entire lesion with a 1 to 3 mm margin and be removed to the level of subcutaneous fat, preventing transection of the base of the specimen to allow for proper staging if it is a melanoma. (See 'Shave biopsy' above.)
Partial punch biopsies of lesions suspicious for melanoma are not generally recommended. Partial biopsies of pigmented lesions have a high potential for misdiagnosis as histologic findings may vary across the lesion [30,44]. However, for large lesions (eg, lentigo maligna), especially if located in cosmetically sensitive areas, multiple scouting punch or incisional biopsies may be performed. (See "Lentigo maligna: Clinical manifestations, diagnosis, and management", section on 'Biopsy and histologic examination'.)
Suturing — Primary closure of a punch wound can be accomplished with one or two, single-layer, interrupted sutures. Some punch wounds can be allowed to heal by secondary intention. Excisions can be closed in one or two layers; two-layer closures yield better cosmetic results for larger wounds. Contraindications to suturing include biopsies in infected or poorly healing skin. These wounds heal better by secondary intention [11].
Choice of suture and needle
●Sutures – The qualities most important in a suture are flexibility, strength, secure knotting, and infection potential [45]. The two major categories of suture are absorbable and nonabsorbable:
•Absorbable sutures – Absorbable sutures are made from synthetic polymer or mammalian-derived collagen (gut). Common synthetic absorbables include polyglactic acid (Vicryl), polyglycolic acid, and polydioxanone (PDS). Absorbable sutures are usually placed deep in larger wounds to reduce skin tension for the superficial closure. (See "Skin laceration repair with sutures".)
•Nonabsorbable sutures – Nonabsorbable sutures are used for skin closure and permanent internal placement. Common nonabsorbable sutures include silk, nylon, and polypropylene (Prolene). Silk and nylon sutures can be braided, adding strength and improving knotting potential, but they are more likely to harbor infection. Polypropylene and unbraided nylon are monofilaments and are less likely to harbor infection, but knots are less secure and more difficult to tie [19,45]. Polypropylene should be considered for the scalp, primarily because it is blue and easy to see. Silk and gut, as natural materials, cause considerable tissue inflammation and have been largely replaced by synthetic suture material [19,45].
Suture size is indicated by the code 0: The more 0's, the smaller the suture diameter. Generally, 3-0 to 5-0 monofilament nylon can be used on the body and scalp, and 6-0 nylon can be used on the face [6,20].
●Suture needles – Suture needles are made of noncorrosive stainless steel that is forged to achieve maximum strength and ductility (the ability to bend under pressure without breaking) [45]. Three types of needle points are common: cutting, tapered, and blunt. Cutting needles allow for easy passage through tough tissue and are ideal for skin.
A code has been developed to denote the purpose of the needle. For skin (FS) and cutting needles (CE) are used on thick skin, while plastic (P), plastic skin (PS), and premium (PRE) are used for cosmetic closures. The size of the needle is ranked by a number, with higher numbers identifying larger needles. Needle curvature is measured in terms of proportion of a circle, with one-quarter, one-half, and three-eighths curves available.
Most biopsy wounds in thick skin can be closed using an FS-3 or CE-3 needle; P-3 can be used for the face, all with a three-eighths curvature. C-17 needles were developed specifically to close punch biopsies and are less expensive than FS, CE, P, or PRE needles.
It is important to reassess the appropriateness of the instruments when wound closing seems more difficult than expected. Needle selection is often a prime factor determining the ease of suturing and final cosmetic result [28]. A larger needle may decrease the difficulty of the job. The needle driver must also be appropriate for the size and type of needle.
Closing — The most common closure technique is a simple, interrupted suture [20]:
●To begin, grasp the needle with the needle holder at midpoint or approximately one-third the distance from the eye. This will provide maximum driving force and diminish the likelihood of bending or breaking the needle. A palm grip is recommended to increase the driving force of the needle through the skin. Place the handle of the holder in the palm, wrap the thumb and fingers around the handles, and extend the index finger down over the tip of the holder near the needle. When holding the skin edges with forceps, be careful to squeeze firmly. Skin should be handled only by forceps with teeth, not with blunt, flat forceps.
●The needle point is placed perpendicular to the skin surface approximately 2 mm away from the wound edge and is driven down, then up into the center of the wound. A second insertion begins in the center of the wound and exits the skin on the opposite side, 2 mm from the wound edge, perpendicular to the surface. If done properly, the suture will make a flask-shaped loop; the loop beneath the skin surface is farther apart than the entry and exit points on the surface. A needle exit in the middle of the wound is not necessary for small excisional wounds and for most punch wounds but depends upon the size of the needle and the ease that the wound edges can be approximated and everted.
●To tie the suture, hold the needle holder parallel to the long axis of the wound with the free end and needle end of the suture on either side of the holder. Wrap the needle end of the suture twice around the holder, then grasp the free end of the suture with the holder and pull through, tightening the knot. At this point, the needle end and free end of the suture should have switched sides relative to the beginning. The process is repeated as needed, reversing the position of the free end and needle end of the suture with each knot. "Approximate, don't strangulate" acknowledges the importance of proper tension on the suture. Excessive tension can be recognized by blanching of the wound edges and may indicate the need for subcutaneous sutures or simply less tension on each suture.
Placement of sutures for elliptical excisions can be facilitated by following the "rule of halves" [20]. The wound is divided in half by the initial suture placement, and each half is itself halved by the subsequent placement of sutures (figure 3). Similar halving continues until all wound edges are approximated. Starting the initial suture at an apex rather than the middle runs the risk of "dog ears" at the opposite apex owing to the creation of uneven wound edges.
The skin tension can be reduced in large wounds by placing a temporary initial suture at the midpoint of the wound but farther from the edge than usual. At a later time, this suture can be removed as the wound is approximated with the permanent sutures.
PROCESSING THE BIOPSY SAMPLE — Excised tissue should be gently removed with small tissue forceps, avoiding crushing the specimen. For evaluation by light microscopy, the specimen should be placed in a 10% buffered formalin solution; each specimen is placed into a separate bottle, and the site is clearly identified. Specimens less than 1 cm in greatest dimension can be adequately fixed in 30 mL of formalin. Larger specimens require more formalin and should be sectioned to ensure adequate fixation. The pathologist should be informed if the specimen is sectioned and advised of the orientation of the lesion by sectioning through its center and marking the normal skin borders with a surgical marker.
Special studies require special handling [1]:
●Direct immunofluorescence – Michel's buffered solution or sterile saline if a sample can be processed within 24 hours [46]
●Electron microscopy – Glutaraldehyde buffered solution
●Bacterial or fungal cultures – Sterile container with nonbacteriostatic saline
●Viral cultures – Viral transport media
PATHOLOGY REQUISITION INFORMATION — Since many dermatologic diagnoses are predicated upon clinicopathologic correlation, the skin biopsy requisition form should include adequate information regarding the patient and the lesion or process biopsied, including the patient's demographics and relevant medical history; the clinical appearance, size, and location of the lesion; clinical course; and previous treatments [47].
POSTOPERATIVE CARE
Wound dressing — All biopsy wounds should be dressed with a thin film of an occlusive ointment to prevent crust formation, then covered with an adhesive bandage or other nonadherent covering, and topped with a gauze dressing and tape [20,48]. Choices for topical occlusive ointments include plain petrolatum and antibiotic ointments (eg, bacitracin, mupirocin). Neomycin-containing agents should be avoided due to the relatively high incidence of contact allergy. Contact dermatitis can also occur with bacitracin, although less frequently than with neomycin [49].
In a randomized trial, similar rates of infection were found in patients who used white petrolatum for postoperative wound care following dermatologic procedures compared with those who applied bacitracin [50]. Thus, to avoid the potential complication of contact dermatitis, we suggest the use of petrolatum for dressing clean wounds from skin biopsies and excisions.
The dressing can be removed in 12 to 24 hours, and the wound should be cleaned with soap and water twice daily. After cleaning, the wound is covered with the occlusive ointment. Wounds healing by secondary intention need to be redressed after each cleaning until healed over or for at least five days; covering the wound site is optional for sutured wounds. Showering is permitted after 24 hours for sutured wounds, but bathing, swimming, and use of hot tubs are prohibited until the sutures are removed [51].
Suture removal — There is a balance between the tendency for wound dehiscence or stretching if the sutures are removed too early and the production of suture marks if they remain too long [19,45]. Sutures on the face generally can be removed in three to five days, followed by the application of semipermeable adhesive strips to reduce wound tension [20,45,48]. Sutures on the chest, abdomen, arms, and scalp can be removed in 7 to 10 days, and those on the back and legs can be removed in 12 to 20 days [20,45,48].
When possible, clinicians should remove sutures from their patients to see the results of their suturing technique on wound healing. Crust should be washed away with wet gauze, then the suture gently lifted near the knot, and one side cut close to the skin surface beneath the knot. The suture is removed by pulling across the wound surface; pulling away from the wound puts tension on the wound and may cause dehiscence [20].
COMPLICATIONS — The major complications of skin biopsy include scarring, pain, bleeding, infection, wound dehiscence, and allergic (primarily contact dermatitis) reactions.
Scarring — Scarring is to be expected with any biopsy that extends into the reticular dermis. Clinicians should try to minimize scar appearance by careful selection of type, orientation, and location of biopsy when possible. Minimizing wound infection and inflammation reduces the potential for abnormal scarring. However, abnormal scarring can occur regardless, particularly on body sites and in patients prone to keloid formation [52]. Biopsies in areas of increased skin tension (eg, joints) may result in spread scars. (See "Keloids and hypertrophic scars".)
Pain — Pain related to skin biopsies can generally be managed with rest, application of ice, and over-the-counter analgesics. Severe pain is rare with punch or shave biopsies.
Bleeding — Bleeding and hematoma formation can be minimized by using a pressure dressing directly over the wound [48]. Tape a folded 4x4 gauze pad tightly over the wound or secure it with an elastic bandage or self-adhering wrap. An ice pack applied for three to five minutes several times during the first 24 hours will also help decrease bleeding, hematoma formation, pain, and edema [48]. (See "Skin surgery: Prevention and treatment of complications", section on 'Intraoperative bleeding' and "Skin surgery: Prevention and treatment of complications", section on 'Hematoma'.)
Infection and dehiscence — Infection, though relatively uncommon, is usually due to Staphylococcus, Streptococcus, or Candida [53]. If the wound is frankly purulent or has an associated cellulitis, culture the discharge and begin empiric oral antibiotics. (See "Acute cellulitis and erysipelas in adults: Treatment".)
Dehiscence (separation of wound edges) is infrequent but can occur when a wound becomes infected or is subject to significant skin stretching, such as in large excisional biopsies over a joint.
Contact dermatitis — The use of certain topical antibiotics (eg, neomycin, bacitracin) on biopsy wounds should be avoided due to the risk of contact sensitization [49]. (See "Skin surgery: Prevention and treatment of complications", section on 'Contact dermatitis'.)
●Allergic contact dermatitis in the wound area presents with erythema, vesiculation, and intense itch. If this occurs, stop the antibiotic and apply a topical corticosteroid ointment.
●Most tape reactions are irritant, rather than allergic, and improve simply by not taping or sometimes by changing the direction of the tape on the skin [54].
DOCUMENTATION — All procedures must be documented in the medical record. Minimal content includes the location and nature of the lesion, indications for the procedure, what was done and how it was performed, specimen disposition, and instructions to and follow-up plans for the patient. Photographs of the lesion/biopsy site are frequently taken prior to the procedure for documentation purposes and may be required for insurance reimbursement. A photograph that orients the site with physical landmarks is helpful for subsequent location identification. This is particularly important when multiple biopsies are done in a region. The following are examples of patient instructions and procedure notes.
Sample patient instructions for wound care
Open wounds — The biopsy done today will heal from the bottom up and sides inward. Remove the adhesive bandage in 12 to 24 hours and clean it twice per day with soap and water. Apply a thin coat of petrolatum, unless otherwise instructed, then cover with an adhesive bandage. This type of wound heals faster when covered. If you have a lot of itching, redness, drainage of pus, swelling, or pain, call the office. Acetaminophen or ice packs may be used for pain control.
Sutured wounds — The biopsy done today has stitches that will need to be removed in _ days. Beginning tomorrow, remove the dressing, wash twice daily with soap and water, and then apply a thin film of petrolatum. Adhesive bandages are optional. Call the office if you experience significant redness, pain, itching, swelling, or drainage of pus. If you are unable to keep your appointment for suture removal, call the office. Acetaminophen or ice packs can be used for pain control.
Sample procedure notes
Shave biopsy — The possible diagnosis of basal cell carcinoma and need for biopsy confirmation was discussed with the patient, and consent for a shave biopsy of the left ear was obtained. Photograph was obtained. The skin was prepped with alcohol; local anesthesia was obtained with lidocaine-epinephrine (lidocaine 1% with epinephrine 1:100,000) and NaHCO3. A shave biopsy into the dermis was performed with a razor blade, and hemostasis was achieved with AlCl3. The biopsy specimens were submitted to pathology in formalin. Petrolatum and an adhesive bandage dressing were applied. Wound instructions were given. The patient will return in two weeks for a wound check and review of pathology results.
Punch biopsy — A possible diagnosis of lupus was discussed with the patient and the need for two biopsies reviewed. Consent for the procedure was obtained. Photographs were obtained. The skin of the right upper, inner, and outer arm was prepped with chlorhexidine and alcohol, and local anesthesia was obtained with 1% lidocaine-epinephrine (lidocaine 1% with epinephrine 1:100,000) and NaHCO3. Two 4 mm punches extending into subcutaneous fat were obtained from the right deltoid area and the right medial arm above the antecubital area. Each site was closed with one 4-0 nylon suture. The specimen from the deltoid area was placed in formalin and from the medial arm into Michel's solution and submitted to pathology. Adhesive bandage dressings were applied. Wound care instructions were given. The patient will return in 10 days for suture removal and review of pathology results.
Elliptical excision — Description: atypical nevus 8x4 mm left upper back. The possible diagnosis, procedure, need for biopsy, potential complications, side effects, and scarring were discussed with the patient, and consent for the procedure was obtained. Photograph was obtained. The patient was placed in the prone position, local anesthesia was achieved using lidocaine-epinephrine (lidocaine 1% with epinephrine 1:100,000) and NaHCO3, and the skin was prepped with povidone iodine and alcohol and draped in the usual sterile fashion. The lesion and a 2 mm clear-appearing margin was excised in an ellipse to the depth of the subcutaneous tissue. Wound edges were undermined bluntly, three 4-O Vicryl inverted mattress sutures were placed in the dermis. The wound was closed with five 4-O nylon sutures. A pressure dressing was applied. Wound care instructions were given. The specimen was sent to pathology in formalin. Final wound length 2.5 cm. The patient tolerated the procedure well. She will return in 14 days for suture removal and review of pathology results.
SUMMARY AND RECOMMENDATIONS
●Indications – The skin biopsy is a simple procedure that can assist with the diagnosis of cutaneous disorders (table 1). Skin biopsies may be performed with shave, punch, or excisional techniques. The type of skin lesion and the location of the biopsy are important factors to consider when choosing which procedure to perform. (See 'Indications' above and 'Site selection' above.)
●Preprocedural considerations – Prior to proceeding to a skin biopsy, patients should be asked about allergies to topical antibiotics, antiseptics, local anesthetics, and reactions to tape. Inquiries should also be made regarding use of anticoagulants, bleeding disorders, and bleeding with previous surgery. Performing a skin biopsy in children may be challenging and requires special expertise. (See 'Preprocedure considerations' above and 'Preprocedure considerations in children' above.)
●Anesthesia – The most common anesthetic used for skin biopsies is lidocaine. Lidocaine-epinephrine may be used to induce vasoconstriction, which decreases bleeding and prolongs anesthesia. Several techniques are useful for decreasing the pain associated with injection. (See 'Anesthesia' above.)
●Biopsy techniques
•Shave biopsy – Shave biopsies are typically used for lesions for which sampling of the full thickness of the dermis and subcutis is not necessary. Shave biopsies are performed with a number 15 scalpel blade or a razor blade. Aluminum chloride or another topical hemostatic agent is used to control bleeding. (See 'Shave biopsy' above.)
Punch biopsy – Punch biopsies involve the removal of a core-shape piece of tissue and allow sampling of the deep dermis. Punch biopsy wounds can be closed with suture or left to heal by secondary intention. (See 'Punch biopsy' above.)
•Excisional biopsy – Excisional biopsies are more time consuming than punch or shave biopsies but are useful for biopsies of larger or deeper lesions. Careful technique is necessary to achieve a good cosmetic result and to reduce the risk of complications. (See 'Excisional biopsy' above and "Fusiform/elliptical excision".)
Excisional biopsy with 1 to 3 mm margins is the preferred procedure for pigmented lesions that are suspicious for melanoma. Only clinicians who are experienced with the deep shave or saucerization biopsy technique should perform this procedure on pigmented lesions. (See 'Biopsy of pigmented lesions' above.)
●Pathology requisition information – Clinical information is useful for pathologists as they interpret the findings in skin biopsies. A clinical description of the lesion and brief history should be submitted with a biopsy specimen. (See 'Processing the biopsy sample' above.)
●Postoperative care – All biopsy wounds should be dressed with a thin film of an occlusive ointment (eg, plain petroleum jelly) to prevent crust formation and then covered with an adhesive bandage. The dressing can be removed in 12 to 24 hours, and the wound should be cleaned with soap and water twice daily. Wounds healing by secondary intention need to be redressed after each cleaning until healed. (See 'Postoperative care' above.)
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