Eccrine porocarcinoma of the head: An important differential diagnosis in the elderly patient

Background: Eccrine porocarcinoma is a rare malignant tumor of the
sweat gland, characterized by a broad spectrum of clinicopathologic
presentations. Surprisingly, unlike its benign counterpart eccrine
poroma, eccrine porocarcinoma is seldom found in areas with a high
density of eccrine sweat glands, like the palms or soles. Instead,
eccrine porocarcinoma frequently occurs on the lower extremities,
trunk and abdomen, but also on the head, resembling various other
skin tumors, as illustrated in the patients described herein.
Observations: We report 5 cases of eccrine porocarcinoma of the
head. All patients were initially diagnosed as having epidermal or
melanocytic skin tumors. Only after histopathologic examination
were they classified as eccrine porocarcinoma, showing features of
epithelial tumors with abortive ductal differentiation.
Characteristic clinical, histopathologic and immunohistochemical
findings of eccrine porocarcinomas are illustrated. Conclusion:
Eccrine porocarcinomas are potentially fatal adnexal malignancies,
in which extensive metastatic dissemination may occur.
Porocarcinomas are commonly overlooked, or misinterpreted as
squamous or basal cell carcinomas as well as other common malignant
and even benign skin tumors. Knowledge of the clinical pattern and
histologic findings, therefore, is crucial for an early therapeutic
intervention, which can reduce the risk of tumor recurrence and
serious complications. Copyright (c) 2008 S. Karger AG, Basel.