Histopathologic characteristics of porocarcinoma. A, Panoramic view showing an ulcerated tumor invading the full depth of the dermis. B, Neoplastic aggregates of varying shapes and sizes. C, Signs of ductal differentiation in some of the neoplastic aggregates. D, Detail of small ducts lined by cuticular cells. (Hematoxylin-eosin, original magnification ×10 [A], ×40 [B], ×200 [C], ×400 [D]).