Pathology of melanoma.

The biologic behavior of several common clinicopathologic types of melanoma is generally predictable by the depth of tumor invasion. However, some individuals have tumors that do no behave as predicted. These include what some authors have called borderline melanoma and minimal deviation melanoma as well as desmoplastic melanoma, thin superficial spreading melanoma with marked regression, and melanomas arising within some nevi. The reasons for the erratic behavior of these melanomas remains enigmatic.