title: Eccrine porocarcinoma of the head: an important differential diagnosis in the elderly patient.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Dermatology, University Hospital, Duesseldorf, Germany.
authors.forename: Peter Arne
authors.initials: PA
authors.lastname: Gerber
authors.forename: Klaus-Werner
authors.initials: KW
authors.lastname: Schulte
authors.forename: Thomas
authors.initials: T
authors.lastname: Ruzicka
authors.forename: Daniela
authors.initials: D
authors.lastname: Bruch-Gerharz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018280:Carcinoma, Skin Appendage / Q000175:diagnosis*; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D004439:Eccrine Glands / Q000473:pathology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012878:Skin Neoplasms / Q000175:diagnosis; D013544:Sweat Gland Neoplasms / Q000175:diagnosis*