INTRODUCTION — The specialty of dermatology includes several office-based minor procedures, many of which are used on a daily basis. Many of these procedures require minimal equipment and can be safely and easily performed in a short amount of time during a regular clinic visit. This topic will cover the following procedures: cryotherapy (cryosurgery), electrodesiccation and curettage of benign and malignant lesions, milia removal, and excision of cysts and lipomas. Other procedural dermatology topics are discussed separately.
●(See "Skin biopsy techniques".)
●(See "Fusiform/elliptical excision".)
●(See "Mohs surgery".)
PREPROCEDURAL CONSIDERATIONS — Informed consent, verbal or written, should be obtained prior to performing any procedure. This includes a discussion of the benefits (often removal of an unwanted lesion) and risks of the procedure. General risks for many of these procedures include dyspigmentation, damage to underlying structures (eg, blood vessels, nerves), recurrence or incomplete treatment of the lesion, infection, and bleeding complications. Individual risks are also noted in each section. (See "Informed procedural consent" and "Skin surgery: Prevention and treatment of complications".)
The clinician should also be comfortable and confident in choosing the appropriate treatment approach for the given lesion of interest and performing the procedure. This includes prior clinical and hands-on experience. Furthermore, the clinician should be confident in the clinical diagnosis of the lesion they are treating. When the diagnosis is in doubt, a biopsy prior to any destructive procedure should be considered.
The clinician should also select an appropriate candidate for any procedure. Considerations include setting expectations for the final result, ensuring the patient can care for the resulting wound, and that it is appropriate and reasonable (ie, avoid removing something for a cosmetic reason if the resulting defect will be less desirable to the patient).
Screening questions prior to the procedure should be gathered. These include the presence of a pacemaker or defibrillator for electrosurgery; a history of any allergies to anesthesia, cleaning solutions, or other substances to be used; and any factors that may result in bleeding, scarring (ie, history of keloids), or other medical complications.
CRYOTHERAPY (CRYOSURGERY) — Cryotherapy, also known as cryosurgery, uses extremely cold temperatures to treat benign and malignant skin lesions. It is a widely available, inexpensive, cost-effective, and rapid treatment that rarely requires anesthesia. This topic discusses cryotherapy in the context of its use in outpatient dermatology.
Principles — Most commonly, liquid nitrogen is used for cryotherapy and has a boiling point of -196°C compared with over-the-counter products, such as dimethyl ether (-24°C) and tetrafluoroethane (-26.3°C), which may be advertised to the public for medical uses (eg, wart removal). Cryotherapy causes tissue necrosis by acting as a heat sink, transferring heat away from cells to the liquid nitrogen. The subsequent freezing of cells causes cell destruction by ice crystal formation, cellular membrane disruption, and vascular stasis, among other mechanisms. It is thought that rapid cooling and slow thawing maximize tissue destruction. Because liquid nitrogen can attain much cooler temperatures than other cryogenic agents and tissue destruction is dependent on this temperature gradient, it is likely the most effective cryogen.
Equipment and delivery methods — Cryotherapy can be administered using several devices and techniques:
●Open spray technique – The most commonly used cryosurgical instrument is a closed-system device (canister) that produces an open spray through a nozzle and trigger (picture 1). The top of the device is unscrewed, and then, using hand and eye protection (in case of any spillage), liquid nitrogen is poured into the canister from the larger storage device. The cap is then screwed back on, and the device is ready to use. Once "released" by the trigger on the canister, the liquid nitrogen rapidly boils into a spray through the nozzle. This allows a fairly precise application of cryotherapy to a skin lesion, while also maintaining a high temperature gradient. Because it is possible to have no direct contact with the patient in this application, it is a practical tool in the outpatient setting that can minimize cross-contamination among patients. A modification can be made using a disposable needle that, after trimming the plastic hub to fit, can be taped/attached to the nozzle tip to make this even more precise or more effective for thicker lesions, such as keloids .
●Cone technique – The spray technique can be modified with a cone (eg, a disposable otoscope cone) to improve the precision of delivery, and it may be directly applied to the skin surface if desired. This minimizes the lateral spread of the liquid nitrogen. Using a knitting gauge (several differently sized diameter holes in one piece) has been reported to be a practical, cost-effective way to modify the cone technique . Various other items may be used to direct the spray as well, such as needle caps, syringe barrels, and micropipette tips .
●Dipstick technique – This technique may be preferable for even more precision and control (eg, on small lesions near the eyes, where the spray technique may be more likely to cause collateral damage). It may also be preferable in children, where one can avoid the loud noise of the spray, which can be unsettling to an already anxious patient. The liquid nitrogen is poured into a container (the author prefers to use a disposable paper cup) that is already on a countertop; one should not hold the container while pouring in case there is any spillage. Using a separate container reduces risk of cross-contamination. A cotton-tipped applicator is then dipped into the container with liquid nitrogen and then quickly applied to the lesion. This technique may not reach temperatures as cold as spray, however. All materials should be discarded afterwards and not used on subsequent patients.
●Cryoprobe/contact cryotherapy – This technique uses a metallic probe that is directly placed onto the lesion, and heat transfer is conducted through the probe. This is less practical in the outpatient setting because of the extra equipment and potential contamination (use is limited to one patient).
●Tweezer technique – Cryotherapy may also be applied with a metallic hemostat or other forceps that have been previously frozen in liquid nitrogen and then clamped onto pedunculated lesions, such as skin tags, with the metal conducting the heat transfer.
Technique — This section will focus on the most common technique used to deliver cryotherapy: using the open spray tip. The dipstick and cryoprobe/contact therapy methods are noted above. (See 'Equipment and delivery methods' above.)
When using the open spray technique, the spray tip is typically held within a few millimeters to >1 cm from the lesion, depending on the size and desired lateral spread of the freeze. The author prefers to deliver liquid nitrogen with a "pulsed" or "stutter" technique (up to one second of delivery, followed by a short pause to prevent excess lateral spread, and repeating until the entire lesion is treated), rather than in a continuous way.
For small, thin lesions, one cycle of cryotherapy may suffice, but for thicker or malignant lesions, at least two total freeze/thaw cycles are preferred by the author. In theory, this will cause more cell damage, and it has been shown to increase clearance of plantar but not common warts . After the first freeze cycle, the lesion is allowed to thaw spontaneously before repeating.
Indications — Numerous benign lesions and a few premalignant and malignant lesions can be treated with cryotherapy. Although not routinely measured in clinical practice, reported minimum temperatures that must be reached in order to adequately treat lesions are as follows [5,6]:
●Melanocytes: -5°C. The relatively mild degree of freezing that causes irreversible melanocyte damage explains why hypopigmentation is a common adverse outcome of cryotherapy.
●Benign lesions: -25 to -50°C. Ideally, keratinocytes should be cooled to -50°C.
●Malignant lesions: At least -50°C.
Benign lesions — Many benign skin lesions can be treated with cryotherapy. Examples include solar lentigines, seborrheic keratoses, keloids, and warts.
Melanocytic or pigmented lesions that do not have a typical or unequivocally benign appearance should not be treated with cryotherapy. As an example, treatment of a facial lentigo with cryotherapy for cosmetic purposes can delay treatment of lentigo maligna and result in obscured borders and wider surgical margins .
Solar lentigines — Gentle cryotherapy can be used to treat solar lentigines. One to two seconds of spray cryotherapy with minimal lateral extension can be attempted. The goal of this is to target pigment and minimize damage to surrounding keratinocytes and tissue. Care must be taken not to overtreat and cause hypopigmentation. Postinflammatory hyperpigmentation is also a possible side effect. (See "Benign pigmented skin lesions other than melanocytic nevi (moles)", section on 'Solar lentigo'.)
In a small uncontrolled study, cryotherapy was more effective than 33% trichloroacetic acid peels on lentigines on the dorsal hands, particularly in patients with lighter skin phototypes . However, cryotherapy has been shown to be less effective than localized dermabrasion and a frequency-doubled quality-switched (Q-switched) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser [9,10].
Common warts — Cryotherapy is widely used as a first-line treatment for warts (common, plantar, and genital) due to its convenience and relative efficacy . For cutaneous warts (verruca vulgaris), the treatment should extend beyond the visible lesion (approximately 2 mm) to treat subclinical virus and avoid "donut" or "ring" warts, resulting from virus replication around the treated area. Creating a visible frozen area that thaws over 30 to 60 seconds is a reasonable goal. (See "Cutaneous warts (common, plantar, and flat warts)" and "Condylomata acuminata (anogenital warts): Treatment of vulvar and vaginal warts" and "Condylomata acuminata (anogenital warts): Management of external condylomata acuminata in adult males".)
Multiple randomized trials and meta-analyses have shown variable efficacy of cryotherapy for the treatment of cutaneous and genital warts, compared with other treatment options, although the quality of evidence is generally low . In one meta-analysis of 11 randomized trials (1639 participants), cryotherapy treatment of anogenital warts showed similar efficacy as trichloroacetic acid peels, podophyllin, and imiquimod, but was slightly less effective than electrosurgery . Cryotherapy was found to have similar cure rates to intralesional bleomycin at three months but had higher recurrence rates after three months (47 versus 19 percent, respectively), although the difference was not statistically significant .
Myxoid cysts — Cryotherapy can be a treatment option for digital myxoid cysts, although it seems to be inferior to surgery and intralesional steroids . (See "Overview of nail disorders", section on 'Digital myxoid cyst or myxoid pseudocyst'.)
Keloids — Cryotherapy, alone or in combination with intralesional steroids, is a treatment option for keloids . Using a needle with its hub modified to attach to the cryotherapy nozzle tip may allow for deeper intralesional treatment of keloids. Some users of this technique suggest making the needle exit through the other end of the lesion, so that the liquid nitrogen passes through the lesion, without damaging the surrounding normal skin . Intralesional cryotherapy using an argon gas-based device has been proposed as an alternative technique for the treatment of keloids .
Infections — In addition to viral warts, cryotherapy has been used to treat several different types of infections, including molluscum contagiosum, cutaneous leishmaniasis, sporotrichosis [17,18], and chromoblastomycosis . (See "Molluscum contagiosum", section on 'Cryotherapy' and "Cutaneous leishmaniasis: Treatment", section on 'Cryotherapy' and "Chromoblastomycosis", section on 'Physical interventions'.)
Hidradenitis suppurativa — Cryoinsufflation has been described to treat sinuses and fistulas of hidradenitis suppurativa . After topical anesthesia, using a 21-gauge needle mounted on a spray cryosurgical unit, sinuses/fistulas can be infiltrated by pulsing the liquid nitrogen for five seconds for three cycles, with one second of pause time between cycles. This treatment is thought to be able to reach smaller cavities, causing scarring that results in symptomatic relief. (See "Hidradenitis suppurativa: Management".)
Actinic keratoses — Cryotherapy is the most widely utilized treatment for actinic keratosis. It can be quickly performed in an office-based setting, is inexpensive, does not require local anesthesia, is well tolerated by patients, and, in most cases, results in good or excellent cosmetic outcome. Care should be taken to biopsy any lesions suspicious for squamous cell carcinoma (SCC), especially if treating tender or very hypertrophic lesions. (See "Treatment of actinic keratosis", section on 'Liquid nitrogen cryosurgery'.)
Malignant lesions — Cryotherapy should be reserved for superficial and well-defined cutaneous malignancies that have a low risk of local recurrence, such as cutaneous squamous cell carcinoma (cSCC) in situ (Bowen's disease) and superficial basal cell carcinoma (BCC). However, even for these tumors, cryotherapy is rarely the author's preferred method of treatment. Ideally, the superficial nature of these lesions should be confirmed with a biopsy prior to destruction.
Local anesthesia is usually required for cryosurgery of malignant lesions, given the depth and the length of freezing required for adequate treatment.
Cryotherapy should not be used for nodular, infiltrative, or other aggressive subtypes of BCC and invasive SCC. It should not be used to treat melanoma, including melanoma in situ. Based on the results of a European survey, only a minority of clinicians use cryotherapy as a nonsurgical option for lentigo maligna . (See "Lentigo maligna: Clinical manifestations, diagnosis, and management".)
Open spray and contact cryotherapy are most frequently used for malignant lesions. As noted above, the goal temperature for treating malignant lesions is significantly lower (colder) than for benign ones, so more aggressive treatment is required. (See 'Indications' above.)
Two freeze-thaw cycles are generally used for cutaneous tumors, although the optimal freeze times for malignant lesions have not been determined. Debulking of thicker lesions is recommended, and suggested freeze times range from 30 to 60 seconds for a 1 cm lesion (one to three cycles), with a lateral spread of 3 to 5 mm or more. Larger lesions likely need longer freeze times. Tissue temperature is usually assessed with clinical assessment, although it may be measured at the deep or lateral margin with a pyrometer and thermocouple needle. The goal tissue temperature is -40 to -60°C .
Cutaneous squamous cell carcinoma in situ — Optimal length of cryotherapy (freeze time) for treatment of cSCC in situ (Bowen's disease) has not been determined. The British Association of Dermatologists recommends at least one freeze-thaw cycle of 30 seconds, or two and up to three 20-second cycles . (See "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)", section on 'Bowen's disease (squamous cell carcinoma in situ)'.)
Penile intraepithelial neoplasia — Cryotherapy has been used to treat penile intraepithelial neoplasia (picture 2). However, in the author's opinion, cryotherapy as monotherapy is likely less effective than topical fluorouracil or surgical excision. In a case series of eight patients, combined treatment with cryotherapy (two freeze-thaw cycles of 10 seconds per lesion) with imiquimod 5% cream three to five times weekly for eight weeks and then one to three times weekly as maintenance for several months resulted in a complete response in all patients . (See "Carcinoma of the penis: Surgical and medical treatment".)
Basal cell carcinoma — Cryotherapy for treatment of BCC should be reserved for low-risk, superficial tumors, particularly in patients who are nonsurgical candidates. The American Academy of Dermatology guidelines list cryotherapy as a potential treatment for only low-risk BCCs when other more effective treatments are contraindicated or impractical . There are conflicting data regarding the efficacy of cryotherapy compared with other treatments for BCC [26,27]. A network meta-analysis found higher recurrence rates and worse cosmetic outcome with cryotherapy . (See "Treatment and prognosis of basal cell carcinoma at low risk of recurrence", section on 'Cryosurgery'.)
Squamous cell carcinoma — Cryotherapy is a treatment option for small, well-defined, low-risk invasive cSCCs when other more effective treatments are contraindicated or impractical . A double freeze-thaw cycle is generally used, and a 30 to 60 second freeze time has been suggested . (See "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)", section on 'Cryotherapy'.)
Postoperative wound care — Wound care is generally minimal for small lesions (eg, actinic keratoses and small seborrheic keratoses). Many patients do not require any special care and are instructed to avoid getting the wound soiled and simply wash with soap and water. Application of petrolatum ointment and a simple bandage is often sufficient as well.
Adverse outcomes and considerations — The most common adverse outcome of cryotherapy is hypopigmentation of the treated area, given the higher sensitivity of melanocytes to temperature. The author avoids cryotherapy on the vermilion border of the lip, due to the risk of blunting of the vermilion/cutaneous border and suboptimal cosmetic outcome. Caution should be taken with aggressive cryotherapy that may result in scarring/retraction, especially in areas with a free margin (nasal ala, ear) and on areas that may heal slowly or poorly (eg, the lower leg). Care should be taken not to damage the nail matrix when treating lesions around the nail. Cryotherapy should also be avoided in those with cold sensitivity (cold urticaria, cryoglobulinemia/fibrinogenemia). Blistering and crusting of the treated area are expected outcomes, and patients should be counseled appropriately. Healing usually occurs within one to three weeks.
CURETTAGE AND ELECTRODESICCATION — Curettage and electrodessication (C&E), also known as electrodesiccation and curettage (ED&C), is a minimally invasive technique widely used to treat superficial skin lesions.
Equipment — C&E uses an electrosurgical device and a handheld curette. The electrosurgical component may be accomplished with a monoterminal electrosurgical unit using true electrodesiccation or electrofulguration (picture 3). The difference between these is touching versus holding the electrosurgical tip at a slight distance from tissue, respectively. This delivers an alternating current, which is converted to heat via resistance in the tissue, thereby destroying it. Battery-powered electrocautery may also be used (see 'Indications' below). If using electrosurgery, an appropriate mask and/or smoke evacuator to reduce the surgical smoke inhaled should also be considered.
The curette is a handheld tool that has a handle and, at the tip, a sharp edge. Most commonly, the curette tip is a small, open cylinder with at least one sharp edge. The tips come in a variety of diameters, with larger diameters more appropriate for larger or thicker lesions, and smaller diameters useful for small lesions where precision (eg, lesions on the face) is a consideration. There are also disposable and nondisposable (cleaned in an autoclave/other device and reused) curettes. Disposable curettes tend to be much sharper, whereas nondisposable ones are blunter. The author prefers to use nondisposable curettes when removing benign lesions, especially on the face, since they may create less deep tissue damage and resultant scarring.
Technique — After cleaning the lesion to be treated, it is typically anesthetized, most commonly with 1% lidocaine, or 1% lidocaine and epinephrine, with or without bicarbonate. Depending on the lesion treated, light electrodessication or electrofulguration may be applied first and gentle curettage after. This is the author's preferred approach for superficial, benign lesions (eg, seborrheic keratoses and sebaceous hyperplasia). For suspicious or malignant lesions, the lesion is typically first shave-biopsied and the specimen is sent for pathology evaluation. Then, there are traditionally three rounds of C&E with a margin of normal tissue, with curettage being performed in three different directions for each round. Curettage or electrodessication may be performed first, depending on the clinician's personal preference. If treating a malignant lesion, forceful curettage (if using a nondisposable curette) is to be applied, and, of note, clearance rates are operator dependent . There is a subjective "feel" of a malignant tumor (friable) versus a "healthy," unaffected dermis (firm). Hemostasis can be achieved with either electrodesiccation or with a topical solution (eg, aluminum chloride).
Indications — Most lesions that are superficial (based entirely or mostly in the epidermis) with little to no dermal component may be treated with C&E. Several of the more common lesions are listed below. Contraindications for C&E include lesions that are infected, fibrotic, or malignant with a significant dermal or deeper component, and recurrent, malignant lesions. Patients with implanted cardiac devices (eg, defibrillators and pacemakers) or other implanted devices (eg, deep brain stimulators or cochlear implants) may not be ideal candidates for use of electrosurgery, and curettage alone may be considered. Battery-powered electrocautery and curettage is another option for patients with implanted devices and may provide similar low recurrence rates .
Benign lesions — Benign lesions can be treated less aggressively than malignant ones, since their removal is typically considered cosmetic. Lesions that can be treated in this matter include seborrheic keratoses, sebaceous hyperplasia, and verrucae. Some lesions can be treated with electrodesiccation alone, including small milia, skin tags, and angiomas (eg, cherry and spider angiomas). (See "Overview of benign lesions of the skin", section on 'Acrochordon (skin tag)' and "Overview of benign lesions of the skin", section on 'Seborrheic keratosis' and "Cutaneous adnexal tumors", section on 'Sebaceous hyperplasia'.)
As noted above, the author prefers to treat both seborrheic keratoses and sebaceous hyperplasia with superficial electrodesiccation or even fulguration first, until the surface of the lesion is charred and may "bubble." Deep tissue damage is avoided (picture 4). The lesion, even if of moderate thickness, will typically then be easily removed by gentle curettage. A nondisposable, somewhat blunt curette (picture 5) is preferred for this in order to minimize damage to the dermis and subsequent scarring. Some lesions may not require curettage and only require removal with gauze after electrosurgery. Other techniques may utilize an epilating (very thin) needle inserted into the "meat" of the seborrheic keratosis or sebaceous hyperplasia, rather than superficially applying electrosurgery. The lesion is also easily removed with a blunt curette or gauze.
A randomized trial comparing cryotherapy with curettage (without electrodesiccation and done with a number 15 blade instead of a curette) found that patients prefer cryotherapy due to simpler wound care, although cryotherapy caused more pain. Cryotherapy was less effective but produced less hypopigmentation . However, in the author's opinion, curettage often produces a superior cosmetic outcome and a more thoroughly treated lesion for benign lesions, compared with cryotherapy.
Of note, an alternative approach to small (<3 mm) seborrheic keratoses is to curette them off without electrodesiccation. A disposable, sharper curette may work better with this method. Medium-sized lesions (diameter and thickness approximately 1.5 and 0.5 cm, respectively) may also be removed by first using gentle cryotherapy for two to three seconds followed by curettage with a nondisposable/blunt curette as noted above.
Premalignant and malignant lesions
Actinic keratoses — Treatment of actinic keratoses is most commonly performed with cryotherapy or topical agents when multiple on a background of field cancerization. However, thick, hypertrophic actinic keratoses may not be adequately treated with the mentioned techniques. Curettage with or without electrodesiccation may be warranted for hypertrophic actinic keratoses as a primary treatment or to prepare the lesion for cryotherapy or field treatment. Any lesions that are tender or very hypertrophic should be sent for pathology to rule out squamous cell carcinoma (SCC); a portion of the dermis is needed to assess for invasive SCC. (See "Treatment of actinic keratosis".)
Cutaneous squamous cell carcinoma in situ — Cutaneous squamous cell carcinoma (cSCC) in situ (Bowen's disease) can be treated with C&E. Recurrence rates range from 2 to 20 percent with follow-up for up to ≥4 years .
Clinicians must be cognizant that clinical signs of residual tumor or large lesions may indicate the presence of an invasive component . These lesions are best treated with surgical excision and histopathologic control. (See "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)", section on 'Bowen's disease (squamous cell carcinoma in situ)'.)
Basal cell carcinoma — Treatment of basal cell carcinoma (BCC) includes many options, depending on the size of lesion, histologic subtype, body location, age of patient, recurrence rate of selected treatment, and functional/cosmetic outcome, among other factors. (See "Treatment and prognosis of basal cell carcinoma at low risk of recurrence" and "Treatment of basal cell carcinomas at high risk for recurrence".)
While fast and cost effective, C&E should be considered for treatment of only small, well-defined, primary (not recurrent), superficial or nodular subtype BCCs that are in low-risk body areas and not in sites of prior radiation therapy. It should not be used for lesions located on terminal hair-bearing sites, due to potential follicular extension of the tumor . The author prefers this treatment for trunk and extremity, superficial, and nodular BCC subtypes that are <2 cm diameter. (See "Treatment and prognosis of basal cell carcinoma at low risk of recurrence".)
BCCs are often treated with three cycles of C&E, with curettage of the entire lesion in three different directions per each cycle. Some lesions may be treated with curettage alone, without electrodesiccation . Treating a small margin (2 to 5 mm) of normal skin beyond the tumor or biopsy site is recommended. If the subcutis is reached with curettage, standard excision or Mohs surgery with margin assessment is recommended .
Cutaneous squamous cell carcinoma — Treatment options for cutaneous squamous cell carcinoma (cSCC) are numerous and dependent on tumor size and location, histologic subtype, and patient-related factors. (See "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)" and "Recognition and management of high-risk (aggressive) cutaneous squamous cell carcinoma".)
C&E can be considered for cSCCs that are low risk, primary (not recurrent), and located in nonterminal, hair-bearing areas . In the author's opinion, treating cSCCs with C&E is reasonable for superficially invasive, well-differentiated tumors that are <2 cm in diameter and located on the trunk or extremities. This option and alternative treatment modalities should be discussed with the patient prior to the procedure. Similarly to BCCs, three rounds of C&E with a margin of normal skin (2 to 5 mm) are used. C&E typically results in inferior cosmesis and is more operator dependent than the other treatment options (eg, surgery or radiation).
Postoperative wound care — The wound is typically covered with petrolatum and a bandage after the procedure for one to two weeks. Soapy water should be used to clean the area daily, taking care not to scrub the wound. The petrolatum and bandage should be replaced at least daily.
Adverse outcomes and considerations — Scarring is the main adverse outcome of C&E, given the amount of damage to the dermis. Infection and bleeding may also occur, but they are infrequent.
EXCISION TECHNIQUES FOR SELECT BENIGN LESIONS — Commonly encountered benign lesions in dermatology that are removed in-office include milia, epidermoid cysts (also called epidermal inclusion cysts), pilar (trichilemmal) cysts, pilomatricomas, and lipomas. (See "Overview of benign lesions of the skin", section on 'Cysts' and "Overview of benign lesions of the skin", section on 'Lipoma' and "Cutaneous adnexal tumors", section on 'Pilomatricoma'.)
These may be removed or excised with varying degrees of ease, which is often dependent on the location and size of the lesion. The following discussion is based on procedures in adults; in the pediatric population, cyst excision should be carefully considered after weighing the risks and benefits, as well as the possibility of dermoid cysts and their connection to deeper structures. (See "Skin nodules in newborns and infants", section on 'Dermoid cysts and sinuses'.)
In adults, midline lesions and those on the scalp may also portend a higher risk of connection to deeper structures. Of note, it is important to feel confident that the lesion of interest is amenable to excision (cyst or lipoma), as the differential diagnosis for a subcutaneous nodule is broad. The lesion should be mobile and not fixed to underlying structures. For instance, the differential diagnosis for a fixed lesion on the skull may include an osteoma or cranial exostosis.
Equipment — Milia removal requires minimal equipment, consisting of a number 11 scalpel blade and either a comedone extractor or two cotton-tipped applicators. (See 'Milia' below.)
Removal of cysts and lipomas generally requires the same equipment and is usually done under sterile technique. The surgical tray consists of forceps, curved Stevens tenotomy (or other curved, short hinge-to-tip distance, preferably with a blunt tip) scissors, scalpel handle and blade (typically a number 15 blade), skin hooks, needle driver and appropriate sutures, and hemostats (picture 6). Typical outpatient surgical equipment should also be available, including an electrosurgical unit, smoke evacuator, proper lighting, and any seating or other equipment needed for patient positioning.
Local anesthesia is sufficient for the vast majority of these procedures. Typically, 1% lidocaine or 1% lidocaine and epinephrine is used, with or without bicarbonate (see "Subcutaneous infiltration of local anesthetics"). Care should be taken to inject the tissue surrounding the cyst and avoid injecting into the cyst itself, as the latter may cause the contents to become projectile when the cyst wall is incised, due to the increased pressure inside.
Milia — Milia are small, superficial cysts containing keratin on the skin. While these typically resolve spontaneously in newborns, they can be persistent in adults. Removal of milia is a simple and cost-effective procedure that can be performed in the office. The author's preferred method of extraction includes minimal equipment (a number 11 scalpel blade and either a comedone extractor or two cotton-tipped applicators). Unless the milia are large, anesthesia is usually unnecessary.
The area is cleaned with alcohol, and the number 11 blade is used to nick the epidermis overlying the milium (picture 7). The contents are then expressed using the comedone extractor or by applying pressure underneath the lesion with the cotton-tipped applicators, using either the cotton-tipped side or the firm, wooden or plastic ends. Special care needs to be taken with lesions on or near the eyes/eyelids. Scarring is typically not noted, unless significant damage to the dermis occurs. Bruising may occur. Hemostasis is typically spontaneous; aluminum chloride is seldom needed and may cause stinging on unanesthetized skin.
Some clinicians may elect to treat small milia (1 mm and below) with electrodesiccation alone, with or without local anesthesia.
Epidermoid cysts — There are several approaches for the removal of epidermoid cysts, including conventional incision technique, minimal excision technique, punch technique, and elliptical excision. Epidermoid cysts are ideally removed when noninflamed, nonruptured, and noninfected. If any of these factors are present, scar tissue and adherence to surrounding tissue limit the options for removal to elliptical excision. Of note, the lining (wall) should be completely removed in all cysts in order to minimize the risk of recurrence.
After excision, the specimens should be sent for histopathologic examination to confirm the diagnosis and exclude malignancy. The author typically always sends every specimen for pathology. Of note, if a typical cyst specimen is obtained (with keratinous debris after sectioning intraoperatively), some clinicians may feel comfortable not sending for confirmation. In one series of 536 excised suspected cysts, 396 were sent for routine histologic examination, based on surgeon's preference, and 77 percent were confirmed epidermoid cysts on pathology . Other diagnoses included lipomas, pilomatricomas, and dermatofibromas, but none of the nonepidermoid cyst lesions was malignant.
Conventional incisional technique — Conventional incisional technique is the author's preferred method for noninflamed, nonruptured, and noninfected epidermoid cysts . The cyst is palpated, and a marking pen is used to identify the borders of the cyst. An incision is made overlying the cyst (approximately as long as the diameter of the cyst) until the cyst wall is identified, and skin hooks or forceps are used to lift the overlying skin so that blunt dissection may be performed to separate the cyst from surrounding tissue; once dissected, the cyst may be extracted from the incision (picture 8). Care should be taken to remove all of the cyst wall and cyst contents to minimize recurrence and a secondary inflammatory reaction, respectively.
An alternative technique where the incision (fenestration) is made with a carbon dioxide (CO2) laser has been described with good aesthetic outcome, including no obvious scars in nearly half of the 47 patients in the study .
The cyst can be removed intact and unruptured, which minimizes the risk of recurrence, although some clinicians may intentionally rupture the cyst and express the contents in order to more easily remove it or reduce scar size. (See 'Minimal excision technique' below.)
Hemostasis is rarely required but can be accomplished by use of aluminum chloride or electrosurgery. One should consider flushing the defect with saline after cyst removal, especially if the cyst has ruptured. This will help to evacuate any keratinous or other debris, reducing the risk of a subsequent inflammatory reaction. After removal, the skin may be sutured. Buried dermal or interrupted epidermal sutures may be used, depending on the thickness of the skin and length of incision.
Minimal excision technique — This is similar to the conventional incisional technique above but with a smaller incision, approximately one-third the diameter of the cyst. The cyst is intentionally ruptured; then its contents are expressed, and the cyst wall is removed through the incision. Saline irrigation is recommended prior to suturing. Although this technique produces a smaller scar, it carries the risk of leaving part of the cyst wall behind and risk of recurrence .
Punch incision — A punch tool may be used to create the incision, with the intention of creating a smaller defect and resultant scar. The punch tool should be used over the cyst, including the punctum, if visible, to intentionally rupture it, and the cyst contents should be expressed. The cyst wall may then be extracted through this defect and then sutured. Compared with elliptical excision, this may be a faster procedure with a smaller scar and similar recurrence and complication rates [39,40].
Elliptical excision — The elliptical excision is the preferred technique for previously infected, ruptured, or inflamed cysts that may be scarred and adherent to surrounding tissue. With this technique, the entire cyst and surrounding tissue are excised as a whole, minimizing the risk of residual cyst wall and recurrence, although the resulting linear scar will be longer .
Other techniques — The rectangular lid excision is a variant used to excise larger cysts (>2 cm in diameter). A rectangle of skin (of length approximately one-half the diameter of the cyst) including the punctum is excised, and further incisions are made along the short sides of the rectangular incision to create one or two "lids" . The cyst is then dissected through this defect, and an advancement flap (single or bilateral) is used for closure. This technique is thought to reduce scarring.
The inverted parachute retraction technique is a variant of the elliptical excision . It uses a suture looped several times through the ellipse of skin overlying the cyst (which is to be removed with the cyst) to help retract the cyst during dissection while reducing tissue damage.
Complications — Complications are rare in epidermoid cyst excision, but they include infection, hematoma formation, seroma formation (especially larger cysts with ample residual dead space), recurrence, injury to adjacent structures (such as blood vessels and nerves), and excessive scarring or deformity.
Pilar cysts and pilomatricomas — Pilar cysts (picture 9A-B), also called trichilemmal cysts, and pilomatricomas (picture 10A-B), also known as calcifying epithelioma of Malherbe, are typically much easier to remove than epidermal inclusion cysts. They are most often found on the scalp and lack an overlying punctum. Pilar cysts and pilomatricomas may be difficult to distinguish from each other clinically, although pilomatricomas are more common in children and may be firmer, irregularly shaped (not a perfectly smooth surface), or indurated due to calcification. Any of the techniques described above (in epidermoid cysts) may be used, but the conventional incisional technique provides a quick and effective method of removal, as the lesion is less easily ruptured (gently clamping with a hemostat may help to provide a means of extraction) and manual pressure is much more successful in extracting the lesion.
The peripheral crescentic excision is a technique described for removal of pilar cysts >1.5 cm in diameter . A crescentic ellipse on the lateral edge of the cyst (with the second arc one-fourth to one-third up from the base of the cyst) is drawn and the excess skin is excised. The cyst is then removed through this defect, and the resultant "hinge flap" is sutured. This results in a smaller incision and possible increased visualization of the cyst and removes redundant skin.
Lipoma — Lipoma excision is typically accomplished with the incisional/minimal excision technique described for epidermoid cysts (see 'Epidermoid cysts' above):
●After palpating and marking the borders of the lipoma, an incision of the skin overlying it is made. The incision can be shorter than the lipoma diameter and often as little as one-third of the lipoma diameter, since lipomas are more malleable than a cyst and can be removed piecemeal if needed. The correct incisional depth is easily identified, as the normal subcutaneous fat will give way to a discrete plane once the lipoma is reached.
●The lipoma may need to be dissected bluntly with Stevens tenotomy scissors or digitally to separate fibrous bands. A typical lipoma can be removed with lateral manual pressure, pushing it through the incision, or pulled out with the assistance of a hemostat after clamping it. Lipomas are often discrete collections of otherwise unremarkable adipose tissue, and palpation of the lesion and digital inspection of the defect are often adequate to assess complete removal of the lipoma.
●After removal, the skin is approximated and sutured. Any redundant skin can be excised as well. The author will almost always send the specimen for histopathologic evaluation.
Variations on lipoma excision may include:
●Z-incision – Two triangular flaps that, when reapproximated, form a "Z" can provide a larger surgical field surface area, which may be advantageous for larger lipomas, compared with a linear incision .
●Hairline incision for forehead lipomas – An incision is made at, or posterior to, the hairline in order to better hide the incision scar. The incision is made to the subgaleal and subfrontalis muscle plane, and blunt dissection (with scissors or another similar tool) is performed, along with manual pressure on the outside of the forehead, to release the lipoma through the posteriorly placed incision. There may be superior cosmetic outcome, although this is a more advanced technique [46,47].
●Pot-lid technique – Similar to cyst removal, a punch tool (approximately 5 mm) can be used to create an incision to the plane of the lipoma, and the lipoma can be removed after blunt dissection and manual pressure (pushing) through this circular defect. The piece of skin excised is placed in saline and then can be replaced and sutured in after lipoma extraction, similar to a "pot lid," acting as a graft .
Special considerations — In many cases, lipomas may be removed very easily, with manual pressure as described above. However, lipomas may be adherent to surrounding tissues (eg, fascia, muscle, or bone) and may underlie or intertwine with other tissues (eg, muscle). Some lipomas are also multilobulated, making removal more difficult.
Both the size of the lipoma and the location may help identify more troublesome lesions.
Forehead lipomas may be submuscular (deep to the frontalis). Imaging should be considered prior to surgical intervention to rule out extension to deeper structures, such as the intracranial space , and to distinguish superficial (technically less difficult) from submuscular lesions for planning purposes. Of note, in a series of 14 patients who received ultrasound preoperatively for a forehead lipoma, the ultrasound was accurate in terms of location (superficial versus submuscular) in only nine patients (64 percent) . In addition to forehead lipomas, lipomas on the flank may be deeper than other sites .
In the author's opinion, imaging with computed tomography scan or magnetic resonance imaging should be considered for larger (>2 cm) and potentially problematic lipomas, especially those on the head and neck, and larger lipomas may be more likely to be adherent to surrounding structures, including those on the posterior neck and shoulders. Smaller lesions may be adequately assessed with ultrasound.
Referral to a general surgeon or head/neck surgeon should be considered if the clinician is not comfortable with the procedure, if the lesion is large enough that general anesthesia is a consideration, or if it involves deeper structures (eg, muscle).
Complications — Complications of lipoma removal include infection, hematoma formation, seroma formation, injury to adjacent structures (eg, blood vessels and nerves), and excessive scarring or deformity.
Postoperative wound care — The principles of wound care after surgical excision of skin lesions are discussed elsewhere. (See "Fusiform/elliptical excision", section on 'Postoperative care'.)
SUMMARY AND RECOMMENDATIONS
●Overview – Minor dermatologic procedures requiring minimal equipment are frequently and safely performed during regular clinic visits. These include cryotherapy (cryosurgery) and curettage and electrodesiccation (C&E) of benign and malignant lesions, milia removal, and excision of cysts and lipomas. (See 'Introduction' above.)
●Cryosurgery – Cryotherapy using liquid nitrogen is a widely available, inexpensive, cost-effective, and rapid treatment. It rarely requires anesthesia, is generally well tolerated by patients, and provides good cosmetic results. It can be delivered with various devices and techniques, depending on the lesion being treated. A variety of benign, premalignant, and malignant lesions can be treated with cryotherapy, including solar lentigines, common warts, keloids, actinic keratoses, Bowen's disease, and superficial basal cell carcinomas (BCCs). (See 'Cryotherapy (cryosurgery)' above.)
●Curettage and electrodesiccation – C&E is a minimally invasive technique widely used to treat superficial skin lesions. It uses an electrosurgical device and a handheld curette. Benign lesions that can be treated with C&E include seborrheic keratoses, sebaceous hyperplasia, skin tags, and verrucae. Cutaneous squamous cell carcinoma (cSCC) in situ (Bowen's disease); small, superficial cSCC; and superficial BCCs located in low-risk areas can also be treated with C&E. (See 'Curettage and electrodesiccation' above.)
●Excision techniques for select benign lesions – Several surgical approaches can be used to remove common, benign, dermal and subcutaneous lesions, including epidermoid cysts, pilar cysts, pilomatricomas, and lipomas.
•Epidermoid and pilar cysts – Most commonly, epidermoid cysts and pilar cysts are removed using the conventional incisional technique (picture 8). Variants of this technique include minimal incision technique and punch incision. A conventional elliptical excision, which removes the cyst and surrounding tissues, is the preferred approach for previously infected, ruptured, or inflamed cysts that are scarred and adherent to the surrounding tissues. (See 'Epidermoid cysts' above and 'Pilar cysts and pilomatricomas' above.)
•Lipoma – Solitary, well-circumscribed lipomas are typically removed using the conventional or minimal incision techniques. Imaging studies may be needed prior to surgery for large or potentially problematic lipomas that are ill-defined or deep-seated (eg, intramuscular or submuscular). (See 'Lipoma' above.)
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