Congenital multiple plaque-like glomangiomyoma.

Congenital glomus tumor is a rare clinical variant of glomus tumor, and glomangiomyoma is the least frequent histologic type of glomus tumor. We report a case of congenital multiple plaque-like glomangiomyoma in a 38-year-old man with multiple nodules and plaques on his left arm and forearm. Histopathologic study showed an angiomatous, nonencapsulated tumor with numerous highly folded dilated vascular lumina scattered throughout the dermis. The lumina were lined by a single layer of flat endothelial cells, and one to several rows of glomus cells were observed adjacent to the endothelial cells. Around large vessels, there was a gradual transition from glomus cells to elongated mature smooth muscle cells with thin and long "blunt-ended" nuclei. Immunohistochemically, there were strong positive reactions for cytoplasmic alpha-smooth muscle actin in glomus cells and smooth muscle cells, vimentin in glomus cells and endothelial cells, and desmin in the smooth muscle cells only. To our knowledge, this is the first case report of congenital multiple plaque-like glomus tumor with the microscopic appearance of a glomangiomyoma.