Fusiform Excision

Specifically, the elliptical or fusiform excision allows for a linear, side-to-side, closure. Mastery of elliptical excision and closure is fundamental to more advanced procedures, including variations on the ellipse itself and planning and executing more complex flaps. An elliptical excision is indicated for the removal of small- to moderate-sized benign or malignant neoplasms as well as for excisional biopsy and scar revision.¹

A fusiform-shaped incision may be used to excise an entire lesion (excision biopsy), or to remove just a portion of involved tissue (incisional biopsy). It is commonly used for smaller procedures because of its relative simplicity, without sacrificing cosmesis: the tapered ends of the resulting defect allow for primary closure of the wound while minimizing “standing cone deformities” or “dog ears” at the ends of the incision. Fusiform excisions are handy for management of squamous cell carcinoma and even basal cell carcinoma and other lesions requiring formal histological identification, including melanocytic lesions.

Fusiform excisions are the preferred method to evaluate margins in melanocytic lesions. A full cross-section may be obtained in a large pigmented lesion, by taking an incisional biopsy, providing the pathologist substantial tissue for examination without creating a large defect. The advent of dermatoscopy notwithstanding, melanocytic lesions can be clinically deceptive and presumed benign lesions may ultimately require wide excision, in which case surgical referral from the outset, and often to a clinic specialising in the care of melanoma, would have been most appropriate. It may nonetheless be relevant for the primary care physician to keep in the back of their mind the margin width for excision of melanoma. Although Breslow Depth has been replaced by the American Joint Committee on Cancer (AJCC) TNM system for overall staging of melanoma, the excision margin of a primary melanoma is nonetheless based on the Breslow stageing (depth) of the lesion:

• margin width should be 1 cm for melanomas 1 mm deep (cure rate > 95%)
• 1 or 2 cm for melanomas 1 to 2 mm deep
• 2 cm for melanomas 2 mm deep.²

The clinical margin for wide local excision of a melanoma in-situ is 5 mm. Yet the margin of the melanoma-in-situ itself is often clinically poorly defined, with extensive subclinical disease. Standard fusiform excision with 5-mm clinical margins result in positive histopathological margins in up to a third of cases.³ However, care must be exercised in making any decision regarding incision or excision because, in the case of a pigmented lesion that later turns out to be a melanoma: an incisional biopsy may potentially seed malignant cells; or an excision biopsy of routine width may likewise seed cancer cells. Alternatively, initial wider-local excision of a lesion that looks suspicious but later turns out to be benign may cause unnecessary morbidity. Where in doubt, always refer.

As a general rule, avoid excisions on the face and especially in young women. Rather, refer patients requiring excision of lesions on their face to a dermatologist or cosmetic surgeon. Where the decision is made to excise a facial lesion, ensure that the long axis of the wound lies parallel to lines of least skin tension. This is a general rule of any skin excision, but particularly so on the face. Nonetheless, whether on the face or elsewhere on the body, due caution should be exercised in patients on anticoagulant therapy, with bleeding disorders, or those with active skin infection.

The clinical indication for the procedure will dictate the width of the fusiform excision. In facilitating adequate closure and cosmesis, the width of the fusiform excision will itself dictate the length of the fusiform excision. Finally, a depth down to the upper part of the subcutaneous fat will usually suffice for most lesions excised in primary care.

Mentally plan the excision. Then palpate the region carefully, noting any pre-existing scarring, superficial or deep, that may compromise easy closure and require a modified technique or, indeed, referral to a surgeon instead. A lesion amenable to a simple excision and primary closure (i.e. no need for flap or graft repair) should be clear after palpation: pinch up a fold of skin directly over the lesion along the line of the planned incision and mentally assess that the two subsequent wound edges will meet. That settled, and the patient having consented to the procedure, set up a non-sterile tray.

Using an appropriate marker, encircle the lesion with the appropriate margins; dependent on the nature of the lesion (2 mm, in the image below). Once the the circular margin has been marked (blue circle, below), the ellipse is planned such that the length of fusiform excision is about three times the circle width (black lines, below). An excision of such extent will help avoid a dog-ear (bunching) at the ends of the sutured excision. But note that certain areas, such as the convex surface of an extremity or the nasal dorsum, require a length to width ratio of greater than 3:1.⁴ That said, the 3:1 ratio is not absolute and can be adjusted down to 2:1, in more supple areas, where this is considered sufficient.⁵ There is some wiggle room (to that rule), but not a lot. With the skin now marked, confirm the earlier impression of apposable wound edges by again pinching the fold of skin over the lesion. That confirmed, now anaesthetise the surgical field.

Use a 10 cc luer-lock syringe to draw-up 1 or 2% Xylocaine (± Adrenaline, depending on anatomical site of procedure). Prep the skin with povidone-iodine and allow to dry, then inject the local anaesthetic solution subcutaneously with a 30 G needle (the finer the needle, the less painful the injection) along the marked incision lines until intradermal blanching of the marked lines appears. Include the sides of wounds in the infiltration, for any lateral undermining that may be needed to help close the wound

Now set up a Sterile Tray:

With sterile gloves, re-prep the wound with povidone-iodine and place a sterile fenestrated drape over the surgical field. Using a pencil grip, take the blade handle and incise with the point of the 15-blade at the fusiform apex that is furthest away. With the blade always held vertical to the skin, make a single, smooth and continuous pass (to prevent notching of skin). As the incision progresses toward the arc of the ellipse, the belly of the blade is held perpendicular to the skin surface, preventing a beveled incision. To prevent bunching of the tissue ahead of the pressure exerted by the blade, traction on the surrounding skin is held with the non-dominant hand or with the aid of traction applied by an assistant. As the opposite apex of the incision is approached, rock the blade back up onto its tip to afford clear vision of the approaching apex under the advancing hand, so terminating the incision right on the apex.⁴ In most circumstances, this first pass should cut through the full thickness of skin; otherwise, a separate (second) pass (if required) extends the incisions down to the level of the fat.

Undermine the central island of skin, at the level of the upper part of the fat layer, and, now with the scalpel turned parallel to the skin surface, incise into this fatty layer to remove the island of tissue in-toto. If necessary, to help achieve closure without undue skin tension, elevate lateral tissue margins through gentle traction on a conveniently placed skin hook (bend and use a 21G needle if no skin hook is available) and undermine the wound margins horizontally; again at the level of the upper part of the fat layer. Undermining is done just under the dermis to preserve the skin’s blood supply.⁵ Be judicious here, careful not to cause undue damage; however, understand that a full 3 cm of undermining is required for every 1 cm skin relaxation gained (in other words, try and aim for no more than a few millimetres of skin relaxation upon wound margin apposition by undermining skin edges by only 5 mm or so). Normally it is sufficient to go about 5–10 mm from the edge of the excision (including the corners) and out into surrounding tissue.⁵ A couple of millimetres of freedom on either side of the wound can go along way to bringing wound edges together but by the same token, any wholesale need for undermining the wound edges suggests that the procedure may have been underestimated; poorly planned to begin with.

Deeply-bury a Vicryl (absorbable) suture of either 3-0, 4-0, or 5-0 calibre, depending on anatomical location, on a reverse-cutting, three-eights curvature needle to appose subcutaneous tissues. This will help produce close approximation of skin edges while helping to eliminating any cavity and prevent post-operative fluid collection and, with that, infection. The suture needle should penetrate the skin surface at a 90° angle. The suture loop should be at least as wide or wider at the base than at the skin surface. The width and depth of the suture loop should be the same on both sides of the wound. Interrupted Nylon (non-absorbable suture) of calibre 3-0, 4-0, 5-0 or 6-0 placed vertically, with small bites of skin, and aim for skin edges to be ever-so-slightly everted upon apposition and, wherever possible, with little skin tension require five throws (ties) to secure knot.⁶

Epidermal sutures are placed to approximate the margins of the skin edge. They should be evenly spaced and placed at roughly the same distance from the wound as the combined dermal epidermal depth. Therefore, sutures placed on the eyelid will be much closer together than those placed on the thick skin of the back.⁴

Close the wound by halves: placing sutures at the midpoint of any open area.

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Wound tensile strength

The epithelial layer becomes sealed (waterproof) after 24 hours. The immediate post-operative tensile strength of wounds with sutures in-situ is pretty good, about 60-70% that of normal skin. Keep sutures in longer for areas of skin subject to repeated tensile loads, which may be for up to 10-14 days in total for wounds of the torso. Although dermal approximation provides the strength and alignment, the subcutaneous layer adding little strength to the repair, sutures placed in the subcutaneous layer may decrease the tension of the wound and improve cosmesis. Collagen formation is necessary to restore tensile strength to the wound. The process begins within 48 hours of the injury and peaks in the first week, but production of collagen and wound remodeling continue for 6 to 12 months.⁶ Most wounds do settle down in that time. Importantly, fresh wounds should, however, be kept away from direct sunlight for that length of time.

The risk of crosshatch marks across the suture line can be minimized by removing the sutures within a week of placement, before the formation of epithelial suture tracks develop. On the face and ears, most skin sutures are removed within 5 to 7 days. Neck sutures should be removed in 7 days and scalp sutures in 7 to 10 days.⁴

• 1 week post removal of sutures (ROS): 5-10% of normal tensile strength
• 60-70 days (2 months) post ROS: 25-35%
• 100 days (> 3 months) post ROS: 70-90% tensile strength

Timing of Suture or Staple Removal

Wound location	Timing of removal (days)
Face	3 – 5
Scalp	7 – 10
Arms	7 – 10
Trunk	10 – 14
Legs	10 – 14
Hands or feet	10 – 14
Palms or soles	14 – 21

References:

1. 390-394_Katz_Sec5_Ch08_final.pdf (facs.org)
2. McCarter, Martin D. “Chapter 68 – Melanoma.” In Abernathy’s Surgical Secrets (Seventh Edition), edited by Alden H. Harken and Ernest E. Moore, 311-18: Elsevier, 2018.
3. Möller, M.G., Pappas-Politis, E., Zager, J.S. et al.  “Surgical Management of Melanoma-In-Situ Using a Staged Marginal and Central Excision Technique.” Ann Surg Oncol  16, 1526–1536 (2009). https://doi.org/10.1245/s10434-008-0239-x.
4. Excisional Surgery and Repair, Flaps, and Grafts | Plastic Surgery Key
5. Tuva Berit Berg-Knudsen, Christoffer Aam Ingvaldsen, Gro Mørk, Kim Alexander Tønseth. “Excision of skin lesions.” Tidsskr Nor Legeforen, 2020.  doi: 10.4045/tidsskr.20.0060.
6. Skin laceration repair with sutures – UpToDate

Further:

• Skin Biopsy Techniques: When and How to Perform Shave and Excisional Biopsy | Consultant360
• Chang TT, Somach SC, Wagamon K, Somani AK, Pomeranz J, Jaworsky C, Bass J, Winfield HL, Sigel JE, Rosenberg AS. “The inadequacy of punch-excised melanocytic lesions: sampling through the block for the determination of ‘margins’.” J Am Acad Dermatol. 2009 Jun;60(6):990-3. doi: 10.1016/j.jaad.2008.09.037. PMID: 19467370.