Desmoplastic Melanoma: A Heterogeneous Entity in Which Subclassification as “Pure” or “Mixed” May Have Important Prognostic Significance

Excerpt

Desmoplastic melanoma (DM) is an unusual variant of cutaneous melanoma that displays many clinical and pathologic differences compared with other types of melanoma. Since the original description of DM in 1971 by Conley et al., 1 the features of more than 600 patients with DM have been documented. These descriptions have shown that DM tends to occur in a slightly older age group than conventional types of melanoma and that it is more frequent in men, is usually amelanotic, and most often occurs in the head and neck region in individuals with chronic sun damage. 2 Pathologically, DM is characterized by the presence of atypical spindle cells separated by collagen fibers or fibrous stroma, and there may be no association with an overlying epidermal or in situ melanoma component. 2 In view of these features, it often presents a diagnostic challenge, and both clinicians and pathologists who are not familiar with DM or its morphological spectrum may not recognize it as a melanoma. As a result, DM is frequently not diagnosed correctly until it reaches an advanced clinical stage. Neurotropism is a common associated feature, and tumors in which it occurs are termed desmoplastic neurotropic melanomas. 3 …