As a rule, dermal neoplasms are associated either with no alteration of the overlying epidermis or with simple atrophy, the latter as if by pressure from the dermal mass. However, there are several dermal tumors which characteristically and contrarywise provoke epithelial activity. The most familiar of these is the so-called granular-cell myoblastoma, which is usually characterized by an associated pseudoepitheliomatous hyperplasia, so striking as to be mistaken occasionally for a squamouscell carcinoma. The pathogenesis of this reaction has so far eluded clarification. Not generally appreciated is the fact that the sclerosing hemangioma (dermatofibroma lenticulare, histiocytoma, nodular subepidermal fibrosis) is also frequently overlaid by evidence of epidermal activity which takes a variety of morphologic forms, including neoplasia. Because of the dearth of information concerning both the existence and nature of the phenomenon embodying the concomitance of epidermal and dermal lesions, the following