Skin Excision for Melanoma

Background Information:

Melanoma is the malignant transformation of the melanocytes within the skin. Melanomas occur most commonly on sun exposed areas including the face, scalp, nail beds, back, and extremities.

Surgical management is critical for diagnosis, staging, and treatment of melanoma. The goals of surgery include: 

• histologic confirmation of the diagnosis, 
• obtaining complete and accurate microstaging of the primary tumor, and, 
• excision of the primary site with an appropriate margin of normal tissue, minimizing the risk of local recurrence without compromising additional staging maneuvers. 

Based on the staging, the procedure may consist of only wide local excision or extend to involve lymph node biopsy or dissection.

Surgical Indication:

If a melanoma is suspected, a full thickness biopsy of the lesion is required for diagnosis and surgical planning. Based on the biopsy result, lesions are clinically staged according to their thickness and the presence of regional lymph node involvement or lymphatic metastases on clinical exam or imaging. The thickness of the melanoma is a key factor in determining the clinical stage of the lesion and the recommended margin of normal tissue to resect (see Table 1)

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Procedure Description:

The surgical approach varies based on the location of the lesion. Most excisions are performed using an elliptical incision which facilitates straight-line closure along natural tension lines. The required margin is measured in the short axis of the ellipse and is typically excised down to the muscle fascia. The specimen is excised and removed and oriented for pathological evaulation.

Sentinel lymph node biopsies provide diagnostic information important for further treatment decisions. They are typically performed for patients with melanomas at intermediate or high risk for lymph node metastasis including melanomas greater than 0.8 mm thick (T1b-4), and melanomas less than 0.8 mm thick but with ulceration (T1b)². For positive sentinel node biopsies, complete lymph node dissection may be required.

Key Anatomy:

Layers of the skin down to the fascia of the underlying muscle belly.

• Epidermis
• Dermis
• Subcutaneous fat
• Lymphatic drainage dependant on melanoma location

• ~Groin lymphatics: Superficial inguinal lymph nodes 

• ~~Drain vulva, scrotum, anus below pectinate line, skin of the groin below the umbilicus. 

Risks:

• Local Bleeding 
• Infection
• Disease recurrence
• Lymphatic leak after sentinel lymph node biopsy or dissection
• Seroma