Histologic features of porocarcinoma

Porocarcinoma is a rare tumor composed of keratinocytes with atypical nuclei present in a poorly circumscribed, infiltrative growth pattern. Necrosis and mitotic activity can be present in both poroma and porocarcinoma, although they typically occur in greater amount in the latter. This porocarcinoma arose within a preexistent poroma (well-circumscribed aggregations of small poroid keratinocytes in the upper portion of the figure). (H&E100x).