Occurrence of basement membranes in pigment cell tumors of the skin, relation to cell type and clinical behavior.

The occurrence, location and intensity of the basement membrane (BM) components collagen IV and laminin in benign and malignant pigment cell tumors was studied by immunohistochemical methods. The results seemed to establish the following findings: junctional nevi display varying continuity of BM; nevus cells in the dermis display more continuous and thicker BM superficially (associated with epithelial type nevus cells); superficial spreading melanoma displays discontinuity of BM, and nodular melanoma and metastatic melanoma display variable BM around tumor aggregates. The variable expression of BM components in this study showed an apparent relationship to tumor cell type and laminin and collagen IV production, partly related to clinical behaviour.