SAN DIEGO — If you're confident that a primary lesion is melanoma, do an excisional biopsy and send the entire specimen to a pathologist.
If you're less certain about the diagnosis, you can do an incisional biopsy of the primary lesion and send the specimen for evaluation, Dr. Avis B. Yount said at an update on melanoma sponsored by the Scripps Clinic. "The goals of biopsy are to establish the diagnosis, determine the best treatment and prognosis for the patient, and determine the type of melanoma, accurate tumor thickness, and information on ulceration and regression," said Dr. Yount of the department of dermatology at the Medical College of Georgia, Augusta.
She defined excisional biopsy as a full thickness biopsy that conservatively excises the entire lesion; its margin is 2–3 mm around the lesion and includes subcutaneous fat. "I try to orient the excision to facilitate future wide excision while maintaining optimal cosmetic and functional results," she said.
Wide excision is not initially recommended because "the lesion may be benign, the excision may be insufficient because of the tumor thickness, and it may interfere with further treatment such as sentinel node biopsy," she said.
If the lesion is located where complete removal would cause substantial disfigurement or a skin graft or flap would be needed for repair, consider proceeding with incisional biopsy. "You can do an elliptical incision through part of the lesion, giving the pathologist the part that will give the best diagnosis, or you can do a punch biopsy or a saucerization-type biopsy," she said. Recent studies have suggested that saucerization might be the most effective approach (J. Am. Acad. Dermatol. 2005;52:798–802).
For incisional biopsy, "you want to biopsy the most nodular or deeply pigmented area into the subcutaneous fat," said Dr. Yount, who also practices in Augusta and Evans, Ga. "Biopsy by shaving, scissor excision, or curettage is not recommended."
She pointed out that there is no evidence that an incisional biopsy has a detrimental influence on the survival of the patient or on the rate of metastases.
When Dr. Yount detects a suspicious lesion on the nail, she removes the entire plate and submits it to the pathologist. "You want to do a transverse biopsy in the nail matrix and a longitudinal biopsy in the nail bed," she said. "Before I remove the nail plate I mark the area of pigment, so that I don't lose the lesion after the nail plate is removed."
Biopsies that are too small create certain challenges. "They may compromise histological assessment, including the accurate assessment of Breslow depth," she said. "You may see a dysplastic or congenital nevus but not the melanoma. I've had seborrheic keratoses abut against a melanoma."
Another problem of small biopsies is that in situ melanoma might coexist with an unidentified invasive component.
"After you've done the biopsy then you need to proceed with excision," Dr. Yount said. "The goals of excision are to cure the patient with low-risk disease, provide local control in patients with probably incurable disease, minimize functional impairment, and minimize cosmetic disfigurement."
Treatment is based primarily on the Breslow depth. "Use judgment in determining margins according to tumor thickness, anatomic location, and skin laxity," Dr. Yount said. She had no relevant conflicts of interest to disclose.