Fusiform/elliptical excision

INTRODUCTION — The design and execution of a fusiform ellipse are fundamental skills of skin surgery. The purpose of this procedure is to remove a skin specimen and, in the process, produce a cosmetically acceptable linear scar. Although the nomenclature for the procedure may vary depending upon the design (eg, elliptical, fusiform, tangent-to-circle), the purpose remains the same.

Since the design of most skin excisions involves sharp, not blunt, points at each end, the most appropriate description of this design is either fusiform or tangent-to-circle, and not elliptical (figure 1). The principles of the fusiform ellipse, such as anatomy, skin tension, tissue movement, and suturing technique, are the same principles necessary to perform more advanced skin surgery, such as advancement flaps, curvilinear excisions, and M- or S-plasties. (See "Overview of flaps for soft tissue reconstruction", section on 'Skin'.)

This topic will discuss the design and execution of the fusiform/elliptical excision. Skin biopsy techniques, Mohs surgery, the principles of graft and flaps for reconstructive surgery, and head/neck anatomic danger zones are discussed separately. The prevention and treatment of skin surgery complications are also discussed separately.

●(See "Skin biopsy techniques".)

●(See "Mohs surgery".)

●(See "Skin autografting".)

●(See "Anatomic danger zones for nerve injury in cutaneous surgery of the head and neck".)

●(See "Skin surgery: Prevention and treatment of complications".)

INDICATIONS — The indications for the fusiform ellipse are the removal of benign or malignant skin lesions and the biopsy of dermatoses or inflammatory disorders in anatomic locations where a linear scar is acceptable. Specific anatomic locations that are particularly amenable to the fusiform ellipse include the trunk, arms, legs, scalp, forehead, and cheek.

Appropriate margins must be defined before removing benign or malignant skin lesions. Recommended margins for common indications are as follows:

●Benign lesions – 1 to 2 mm

●Uncertain pigmented lesions – 1 to 3 mm [1] (see "Atypical (dysplastic) nevi", section on 'Excisional/complete biopsy')

●Severely dysplastic nevi – 5 mm [2]

●Low-risk nonmelanoma skin cancers [3,4] (see "Treatment and prognosis of basal cell carcinoma at low risk of recurrence", section on 'Standard surgical excision' and "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)", section on 'Standard excision'):

•Basal cell carcinoma – 4 to 5 mm

•Squamous cell carcinoma – 4 to 6 mm

●Melanoma [5] (see "Surgical management of primary cutaneous melanoma or melanoma at other unusual sites"):

•In situ – 0.5 to 1 cm

•Breslow ≤1 mm – 1 cm

•Breslow >1 to 2 mm – >1 to 2 cm

•Breslow >2 mm – 2 cm

RELATIVE CONTRAINDICATIONS — The fusiform excision for the elective removal of benign lesions should be considered with great caution in the following situations:

●Patients with a history of keloids or hypertrophic scars (see "Keloids and hypertrophic scars", section on 'Prevention').

●Patients with impaired hemostasis – For patients with impaired hemostasis (eg, platelet count <50,000 or international normalized ratio [INR] >3), it is most prudent to delay surgery until the coagulation abnormalities have been addressed, unless the histologic diagnosis of a lesion or dermatosis is of critical importance [6].

●Patients on oral anticoagulants – There is general consensus that patients on oral anticoagulants undergoing skin surgery continue their oral anticoagulant medications; in patients taking warfarin, the INR should be maintained within the therapeutic range [7]. (See "Skin surgery: Prevention and treatment of complications", section on 'Patients on anticoagulants and antiplatelet agents'.)

PREOPERATIVE EVALUATION — Before designing and executing a fusiform ellipse, it is important to take a thorough but focused preoperative history and perform a complete physical examination:

●The risks of bleeding and infection should also be carefully evaluated and discussed with the patient prior to obtaining the informed consent. (See 'Potential complications' below.)

●Medications, including over-the-counter supplements, should be reviewed for items that may increase the risk of postoperative bleeding. Current recommendations for cutaneous surgery discourage the discontinuation of any antithrombotics or anticoagulants prior to surgery because of the related risk of thrombotic complications [8,9]. (See "Perioperative management of patients receiving anticoagulants".)

●In most cases, antibiotic prophylaxis is not required before cutaneous surgery. However, antibiotic prophylaxis is indicated in the situations illustrated in the algorithm (algorithm 1) [10]. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

●Particular attention should be paid to any accompanying pathology report that is related to the lesion in question.

●Proper site identification is critical and should involve the examination of the available documentation and input of the patient or family/caregiver, if necessary, to avoid the possibility of wrong site surgery [11].

●Anticipatory guidance should be provided regarding specific activities that patients may wish to participate in during the postoperative period. Specific restrictions of activity, weight lifting, and work-related responsibilities should be clearly communicated. (See 'Postoperative care' below.)

●All patients should be counseled that a fusiform ellipse will result in a scar.

DESIGN OF THE FUSIFORM ELLIPSE — The first step in the design of a fusiform ellipse is to carefully outline the clinical margins of the lesion itself, and then outline the appropriate amount of additional tissue to remove around it (margins) using a marker. Finally, the fusiform ellipse is drawn around this.

As a rule of thumb, it is most advantageous to orient a fusiform ellipse so that it parallels or lies within a relaxed skin tension line while patients are in an anatomically neutral position, such as sitting or standing, rather than recumbent. In addition, the author considers two other factors when orienting a fusiform ellipse: maximum tension during activity and local tissue laxity. Various schematics of relaxed skin tension lines in different anatomic locations are available as a guide (figure 2A-B) [12].

It is important to manipulate the skin surrounding the lesion with the patient in the anatomically neutral position by gently pinching between the index finger and thumb in order to fully evaluate the most appropriate orientation for the fusiform ellipse. Generally, orienting the fusiform ellipse along the axis of greatest laxity, which is usually along a relaxed skin tension line, will produce the least noticeable final scar (picture 1).

In areas of relatively high skin tension, such as the back, forearm, or leg, it may be prudent to orient the long axis of the fusiform ellipse along the axis of greatest tension during movement. It is helpful to have the patients assume a position of maximum tension for each anatomic area (eg, standing, squatting, crossing arms in front of the chest) when determining the appropriate orientation of the fusiform ellipse. At times (especially on the back) this orientation may be different from the relaxed skin tension lines, and rarely even perpendicular to them.

With the proper orientation of the fusiform ellipse in mind, the lines connecting the circle and the tips of the ellipse should be marked. The most common design for a fusiform ellipse involves a length-to-width ratio in the range of 3:1 to 4:1 and corresponding angles at the apices in the range of 30 degrees. In most instances, these ratios facilitate adequate tissue removal while minimizing or eliminating a standing tissue cone ("dog ear" (picture 2)) once the surgical defect has been linearized with sutures.

The lines that connect the circle to the tips of the ellipse may be either curved or straight and thereby result in either a fusiform or tangent-to-circle (rhombic) shape (figure 1). The tangent-to-circle is simpler to design, easier to execute (it is easier to cut a straight line than a curved line), and removes less tissue. One potential disadvantage of the tangent-to-circle is the possibility of a small gap that tends to develop in the center of the linear repair at the point where the paired tangential lines oppose each other. This phenomenon tends to be most common when performing surgery on the scalp. However, this gap is easily negated with meticulous suturing or designing the opposing tangents to be slightly offset [13].

EXECUTION OF THE FUSIFORM ELLIPSE

Patient and surgical site preparation — Proper position of the patient should simultaneously allow the patient to be comfortable, minimize tension at the surgical site, and optimize the posture of the practitioner who will perform the surgery. The surgical site should be prepared with antiseptic (eg, chlorhexidine or povidone-iodine) and draped.

Effective and rapid local anesthesia may be obtained with 1% lidocaine and epinephrine (1:100,000 to 1:200,000) and should include at least 1 to 2 cm of skin beyond the intended incision line (see "Subcutaneous infiltration of local anesthetics"). Before executing the excision, a procedural pause or time-out should be completed in order to verify the correct patient with two separate patient identifiers (such as name and date of birth) and the correct location for the surgery.

Excision — The excision involves the following steps:

●Incision – Three-point counter tension (picture 3) should be implemented at the surgical site in order to facilitate a smooth incision that extends through the dermis at 90 degrees to the surrounding skin and in a single motion that avoids cross-hatching at the tips of the specimen. The appropriate depth for most fusiform excisions is the mid-to-upper adipose layer except for certain locations such as the scalp (subgaleal plane), arm/leg (above fascia), and the cartilaginous portions of the ear/nose (above perichondrium). A scalpel or iris scissors should be utilized to extend the incision in a uniform plane below the fusiform specimen so that the sides and base of the surgical defect form a 90 degree angle.

●Undermining – Undermining is the mechanical disruption of attachments between the dermis/superficial adipose tissue and the deeper soft tissues, and it is utilized to increase tissue movement as well as wound eversion. Very little, if any, undermining is needed to bring together a well-designed fusiform ellipse. However, undermining around the entire defect, including the tips, will maximize the final cosmetic result in regions where this is important, and may be necessary in areas that are tight in order to provide additional lateral tissue movement for wound closure [14]. The undermining is usually carried out in the plane of tissue removal (above) using a scalpel or scissors. However, undermining may need to be minimized or even avoided in patients on anticoagulants.

●Hemostasis – Hemostasis should be obtained with electrocautery in a purposeful, pinpoint, and meticulous manner. Actively bleeding vessels should be visualized clearly prior to the application of electrocautery. If necessary, a surgical assistant may utilize skin hooks for better visualization. Less precise application of electrocautery in the "general vicinity" of a bleeding vessel without pinpoint application unnecessarily damages healthy tissue, which may potentially impede wound healing and increase the risk of infection. Conversely, the inadequate utilization of electrocautery may increase the risk of a postoperative hematoma. The manifestations of a hematoma tend to become apparent several hours after the surgery, corresponding to the time point at which the vasoconstrictive properties of epinephrine have waned.

As a general rule, it is prudent to submit all skin specimens for pathologic review, even if the lesion is assumed to be benign. (See "Skin biopsy techniques", section on 'Processing the biopsy sample'.)

Suturing — The main purpose of suturing the wound that results from the excision of a fusiform ellipse is to facilitate the healing and achieve a well-hidden, thin linear scar. The wound edges of a fusiform ellipse are most commonly reapproximated with two layers of sutures. The first, or buried, layer of sutures should be placed on the dermis and subcutis and should be composed of absorbable material that is generally of 4-0 or 3-0 caliber on the trunk, scalp, and extremities and 5-0 or 4-0 on the face. A variety of suture materials may be utilized to reapproximate the epidermal edges. The most common option is nylon and is generally 5-0 or 6-0 caliber for the face and 5-0 or 4-0 caliber for the trunk, scalp, and extremities. Alternatives to nylon suture are staples, fast-absorbing gut (generally 5-0 caliber), or 2-octyl cyanoacrylate.

A buried vertical mattress suture is the mainstay for reapproximating of wound edges in skin surgery. A simple mantra that can help conceptualize the technique is "deep to superficial, superficial to deep." The purpose of the buried vertical mattress suture is to optimize wound edge eversion (and thereby optimize the final aesthetic outcome) while burying the surgical knot in the deep dermis/superficial adipose tissue. In order to obtain adequate wound eversion and minimize "dead space" at the base of the wound, the first throw of the suture should enter the reticular dermis at the junction of the adipose tissue (figure 3). The suture should then pass through the dermis along the natural curve of the needle to a maximum height in the papillary dermis and then exit the dermis approximately 1 to 2 mm below the apex of the suture path in the dermis.

This technique should be mirrored exactly on the opposing wound edge. Depending upon the wound tension, buried sutures may be placed every 0.5 to 1 cm. The extent to which the wound edge is everted must be carefully considered. Too much eversion may result in a "rope-like" scar, while insufficient eversion may result in a depressed scar. With the wound edges sufficiently approximated, the alignment of the epidermal edges should be reinforced with either simple or running sutures or cyanoacrylate tissue adhesive.

POSTOPERATIVE CARE — Wound care recommendations may vary from practice to practice. The author prefers the following simple plan:

●The postoperative bandage is made by applying a thin layer of white petrolatum followed by a pressure dressing consisting of nonstick gauze, a layer of regular gauze, and adhesive tape.

●The postoperative bandage may be removed after 24 hours and the patient may shower immediately.

●The daily routine after removal of the postoperative bandage includes washing the surgical site twice daily with mild soap and warm water followed by a layer of white petrolatum. A bandage may be applied at the discretion of the patient but is not necessary.

Topical antibiotics for prophylaxis of surgical site infection in clean surgeries should be avoided since there is no evidence that they improve wound healing [15-17]. Furthermore, the routine, prophylactic use of topical antibiotics for clean skin procedures increases the risk of antimicrobial resistance as well as the risk of allergic contact dermatitis for the patients [15,18]. (See "Skin surgery: Prevention and treatment of complications", section on 'Postoperative topical antibiotics'.)

Activity restrictions should be both generalized for all patients and, to the extent possible, customized for each patient depending upon his/her activities. General restrictions include:

●Do not lift more than 15 to 20 pounds, at least until suture removal

●No swimming or bathing in standing water, at least until suture removal

●Minimize activities that put strain on the wound

TIMING OF SUTURE REMOVAL — Suture removal recommendations vary based upon the anatomic site. Sutures on the face may be removed between five and seven days after surgery. In all other locations, including the scalp, trunk, arms, and legs, the sutures are removed after 10 to 14 days.

POTENTIAL COMPLICATIONS — The three most common postoperative complications after excision of a fusiform ellipse are hematoma, infection, and dehiscence. Each may happen independently, although all may occur simultaneously. A thorough exam and history with appropriate bacterial cultures, as indicated, are keys to accurate diagnosis and management.

Hematoma — Postoperative hematomas generally develop within the first 24 to 48 hours. Patients typically present with expanding induration of the wound site with associated bruising. The presence of blood in the subcutaneous tissue may be confirmed either by aspirating with an 18-gauge needle and syringe or by removing a portion of the superficial and deep sutures. Lidocaine without epinephrine should be used to obtain adequate anesthesia and to avoid the possibility of introducing temporary vasospasm to an actively bleeding vessel as a result of epinephrine. If a hematoma with active bleeding (associated with bright red blood) is identified, it is prudent to open the incision in order to identify the bleeding vessel and obtain hemostasis. The wound may then be resutured or allowed to heal by second intention. In either case, a seven-day course of oral antibiotics that cover common skin contaminants (eg, Staphylococcus and Streptococcus) may be considered. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Antibiotic selection'.)

In some cases, when identified later in the postoperative course (eg, several days after surgery), the hematoma may be organized and the source of bleeding may have stopped. If the hematoma is stable and identified several days after surgery, there are no signs of infection, and it is not located in a cosmetically sensitive area (eg, trunk, extremities), it may be reasonable to either evacuate the hematoma and treat the wound as described above or follow a course of watchful waiting, as the hematoma will likely resolve over time.

Infection — Postoperative infections generally develop three to five days after surgery. They are associated with increasing warmth, redness, pain, and induration. Sometimes purulent material is expressed when lateral pressure is applied to the surgical site. Appropriate care in these instances includes obtaining a bacterial culture of the wound with antimicrobial sensitivities, institution of hot compresses two to three times daily and consideration of empiric oral antibiotic therapy that may be modified, if necessary, when culture results return. (See "Skin abscesses in adults: Treatment", section on 'Indications for antimicrobial therapy'.)

Occasionally, purulent material may be extensive. In such cases, it may be prudent to remove all sutures, drain any purulent material, flush copiously with sterile saline, pack the wound, and allow it to heal by second intention.

Wound dehiscence — Wound dehiscence may occur at any point during the wound healing process. It is imperative to determine if either an infection or hematoma contributed to the dehiscence and start the appropriate treatment.

Some of the most likely locations for dehiscence are the back, arms, and legs due to a combination of high tension on the wound, postoperative edema, and patient activity. If a dehiscence develops, it is preferable to allow the surgical wound to heal by second intention. In most cases, the wounds will heal with acceptable function and aesthetics.

EVOLUTION OF THE FUSIFORM ELLIPSE TO OTHER PROCEDURES — A variety of modifications can be made to the fusiform ellipse, each with its own purpose [13]. Examples of modifications in the design of a fusiform ellipse include:

●Curvilinear design – A curvilinear scar can be produced by modifying the fusiform ellipse such that the convexity of each side of the surgical specimen is aligned concentrically rather than as mirrored images. Commonly, the lengths of the arcs on each side will be unequal. Therefore, it is important to follow the "rule of halves" in order to minimize the development of standing tissue cones (figure 4).

●M-plasty – In order to effectively shorten the length of the surgical scar from a fusiform ellipse, one may implement an M-plasty at either end (figure 5). A helpful method to conceptualize the design of an M-plasty involves imagining the tip of the fusiform ellipse being "folded back" on itself in order to sufficiently shorten the scar.

●S-plasty – An S-plasty modification can be particularly useful when designing an excision on a highly contoured location such as the arm or leg. An S-plasty is designed by introducing a curved line opposite of a straight line on the same half of the ellipse. By following the rule of halves for a set of opposing curved and straight lines, a curve will be introduced into the final sutured wound, with the final product taking the shape of an "S" and the curved components lying flatter against a curved surface (figure 6).

SUMMARY AND RECOMMENDATIONS

●Design of the fusiform ellipse – The design and execution of a fusiform ellipse are fundamental skills of skin surgery. The first step in the design of a fusiform ellipse is outlining the clinical margins of the lesions with a marker and determining the appropriate amount of additional tissue to remove. As a rule of thumb, the long axis of the ellipse should be parallel or lie within a relaxed skin tension line (figure 2A-B) while patients are in an anatomically neutral position. (See 'Design of the fusiform ellipse' above.)

●Execution of the elliptical excision:

•Incision – The incision is made through the dermis at 90 degrees to the surrounding skin, in a single motion that avoids cross-hatching. The appropriate depth is in most cases the mid-to-upper adipose layer. (See 'Excision' above.)

•Suturing – The main purpose of suturing the wound is to facilitate healing and achieve a well-hidden, thin linear scar. The wound edges of a fusiform ellipse are usually reapproximated with two layers of sutures. The first, or buried, layer of sutures should be placed on the dermis and subcutis and should be made with absorbable material that is generally of 4-0 or 3-0 caliber on the trunk, scalp, and extremities and 5-0 or 4-0 on the face. A variety of suture materials may be utilized to reapproximate the epidermal edges. The most common option is nylon and is generally 5-0 or 6-0 caliber for the face and 5-0 or 4-0 caliber for the trunk, scalp, and extremities. Alternatives to nylon suture are staples, fast-absorbing gut (generally 5-0 caliber), or 2-octyl cyanoacrylate. (See 'Suturing' above.)

●Postoperative care – The postoperative bandage is made of a thin layer of white petrolatum followed by a pressure dressing consisting of nonstick gauze, a layer of regular gauze, and adhesive tape. It can be removed after 24 hours and the patient may shower immediately. The timing of suture removal varies based on the anatomic site. Sutures on the face may be removed between five and seven days after surgery. In all other locations, the sutures are removed after 10 to 14 days. (See 'Postoperative care' above.)