Eccrine angiomatous hamartoma (nevus): immunohistochemical findings and review of the literature.

Eccrine angiomatous hamartoma (nevus) is a rare form of congenital tumorous malformation with proliferation of eccrine secretory coils and ducts, surrounding capillary angiomatous channels and occasionally other minor elements. To date, there have been only about 24 cases reported in the literature. We report an additional case with more detailed description of the microscopic findings, including immunohistochemical observations. The patient was a 28-year-old female who presented with painless, flesh- to reddish brown-colored, violaceous or bluish subcutaneous nodules on the extremities and trunk. The tumors did not show sweating following exertion. The histologic features were comparable to the previously reported cases. The hamartomatous eccrine sweat glands and ducts and a few apocrine glands demonstrated qualitatively diminished antigens commonly found in the eccrine sweat apparatuses, such as carcinoembryonic antigen (CEA) and S-100 protein. The findings of CD34, CD44, human nerve growth factor receptor and Ulex europaeus antigens have not been previously reported. The histologic features suggested a "hamartomatous" growth rather than a true neoplastic process.