Follicular malignant melanoma: a variant of melanoma to be distinguished from lentigo maligna melanoma.

Follicular malignant melanoma can be regarded as a rare and unique presentation of melanoma. It is characterized by a deep-seated follicular structure in which atypical melanocytes extend downward along the follicular epithelium and permeate parts of the follicle as well as the adjacent dermis. The clinical diagnosis of follicular malignant melanoma may be difficult because the tumor mostly resembles a comedo or a pigmented cyst. We studied five cases of follicular malignant melanoma in which the patients were between 61 and 82 years old. Three lesions were localized on the nose, one on the cheek, and one on the back of the neck. Clinically, all five cases measured distinctly less than 0.5 cm in size. While lentigo maligna is traditionally known as a pigmented macule in actinically damaged skin that gradually evolves in a slow process before invasive growth, three follicular malignant melanomas had developed in relatively short timeframes of 9 months to 1 1/2 years. In all five cases the inconspicuous clinical appearance did not herald a malignant melanoma with invasive growth. Follicular malignant melanoma underlines the importance of a correct excision technique with subsequent histologic workup and diagnosis. Superficial shave excision or even laser treatment in these specific cases may lead to a fatal prognosis for the patient.