Tubulopapillary hidradenoma-like tumor of the mandible: clinicopathologic and immunohistochemical features.

Tubulopapillary hidradenoma is a benign sweat gland tumor that appears as a well-defined, superficially located dermal nodule. It combines ductal as well as apocrine and eccrine glandular differentiation. Microscopically, the tumor is composed of tubular structures that characteristically show intraluminal non-villous papillary projections and a peripheral myoepithelial cell layer. A tumor that is histologically and immunohistochemically identical to tubulopapillary hidradenoma occurred in the mandible of a 73-year-old man and resulted in considerable diagnostic difficulty. The neoplasm developed in a mandibular cyst and recurred 5 years after initial enucleation. This is the first report of a central (intraosseous) sweat gland adenoma of the mandible. The differential diagnosis and possible histogenesis are discussed.