Skin Cancer Surgery – Case study:

History: 38 year old patient of Chinese descent was referred to me by her GP with a cyst on her L forearm. The referral stated that the lesion had been present for 3 months and was diagnosed as a sebaceous cyst. It was enlarging and at times been inflamed and as it was a 3 cm lesion, the GP felt more comfortable referring it for excision.

Findings: When I examined the patient, I could not find a typical punctum of an epidermal cyst, which in itself is not unusual (Sebaceous cysts are anatomically epidermal and therefore superficial – it is therefore important to understand the planes and skin anatomy in cutaneous surgery). Intra-operatively, the cyst was located more in the dermis with a clear plane between the epidermis and the lesion, thereby raising suspicion.

Histology: The pathology report confirmed a ‘sebaceous carcinoma’ (always send even benign looking sebaceous cysts for histology)

Sebaceous Carcinoma
Sebaceous carcinoma is an aggressive tumor derived from the adnexal epithelium of sebaceous glands. The tumour occurs most commonly in older adults and is more common in females. The Meibomian glands of the upper eyelid are the most commonly affected site. Mortality rates for ocular sites are 20 - 30 %, however the following features are associated with an even more unfavorable prognosis. Extraocular cutaneous sites have a better prognosis.

Worse prognosis if:

Bailet reported a review of 92 patients with extraocular or skin sebaceous carcinoma and found a recurrence rate of 29% and metastases in 21%.

Evaluation of the patent with cutaneous sebaceous carcinoma includes a complete skin exam, palpation of nodes. Patients must be evaluated for the Muir-Torre syndrome -- The Muir-Torre syndrome (MTS) is an autosomal dominantly inherited disorder, characterized by visceral malignancies (especially upper and lower GI) and sebaceous skin lesions. Reports have identified families whose spectrum included adenocarcinomas of numerous gastrointestinal sites, carcinomas of the endometrium, ovary and breast, papillary transitional cell carcinoma of the ureter, a range of cutaneous tumors, as well as keratoacanthomas.

Treatment: Surgical excision is the mainstay and many authors advocate 1—2 cm margins for extra-ocular cutaneous sebaceous carcinoma, although some guidelines state a minimum of 5 mm. Ocular lesions often need exenteration of the eye. Sebaceous carcinoma has a tendency for local recurrence and Moh’s surgery has not been of major benefit due to the multicentricity of tumours. Radiation therapy has been considered as adjunctive or palliative therapy but is generally not recommended as a primary treatment.  Metastatic disease occurs in 14 - 25 % of cases. Most metastases occur in regional lymph nodes, followed by liver, lung, brain and bone. Regional lymph node metastases are treated with radical neck dissection. Treatment of metastatic disease includes surgery, radiation, chemotherapy or a combination of these modalities. Metastatic disease has a >50 % mortality.

Surgical tip:

I use a Z-plasty for 3 purposes:

• change direction of scar in a revision
• interrupt scar line (when excising lesions across a joint)
• lengthen scar (overcome contraction such as after previous surgery or burn)

As shown in the diagram above, the lengthening occurs across the central limb of the Z (horizontal) when the flaps are transposed.
In a Z–plasty:

• The limbs must be of equal length
• Making the limbs longer while keeping angle constant causes lengthening
• Increasing angles (without increasing limb length) also causes lengthening
• Angle degrees 30/45/60 cause percentage increase in length of 25/50/75