Superficial Spreading Melanoma

An 82-year-old man with Alzheimer's disease and atrial fibrillation was referred for evaluation of a lesion (A) present for an undetermined period. It was initially noted 1 week earlier, at his first office visit with a geriatrician.

Physical examination showed a 3-cm, irregularly pigmented, asymmetric plaque affecting the back. A punch biopsy from the most deeply pigmented area was performed.

Pathology studies revealed irregular nests of large and atypical melanocytes in the papillary dermis to a depth of 0.49 mm. The melanocytes showed mitoses and cytologic pleomorphism. A dense, band-like infiltrate was present at the dermoepidermal junction. Papillary dermal fibrosis and vascularization were consistent with regression. The diagnosis of a superficial spreading melanoma, Clark's level II, was made.

Superficial spreading melanoma is the most common type of melanoma affecting whites. It usually affects the back in men and the lower extremities in women. The lesion initially expands radially over several years. The irregular red, white, and blue pigmentation generally associated with melanomas is most evident in this type. Red represents areas of inflammation; white, areas of regression; and blue, areas of deep pigmentation and vertical growth.

Excisional biopsies are recommended when there is a strong suspicion of melanoma; re-excision is required, with appropriate margins based on tumor thickness. A margin of 1 cm is recommended for tumors less than 1 mm thick, 1.5 cm for tumors 1 to 1.5 mm thick, 2 to 3 cm for tumors 1.5 to 4 mm thick, and 3 cm for tumors 4 mm thick.

Because this patient was being treated with warfarin for atrial fibrillation, a conservative approach was used: a punch biopsy from the site likely to show the greatest depth of invasion was performed, and an excision with 1-cm margins was done at a later date.

Other variants of melanoma include nodular melanoma (B) and acral-lentiginous melanoma (C). Nodular melanoma shows a rapid vertical growth phase that manifests as a nodular tumor; it most commonly affects the trunk in men and the legs in women. The lesion may appear blue or black and hyperkeratotic, or red, ulcerated, and crusted.

Acral-lentiginous melanoma is the most common type of melanoma in persons with dark skin, including Asians, blacks, and Hispanics. It primarily affects acral areas, including the palms and nail beds, and-most commonly-the soles. A biopsy of a single pigmented streak in the nail plate needs to be done to rule out an acral-lentiginous melanoma. Nodular melanoma and acral lentiginous melanoma usually have a worse prognosis than lentigo maligna melanoma and superficial spreading melanoma because of the greater depth of invasion at the time of diagnosis.

Referral to a dermatologist is appropriate for a patient with newly diagnosed malignant melanoma. Persons with a history of this disease are at increased risk for recurrence and should be followed closely.