Abstract
We report the case of a 57-year-old man who first developed several purplish blue nodules with tenderness on his right arm when he was 12 years old. The nodules were excised but thereafter recurred several times. The histopathological findings showed tumor nests in the dermis with dilated vascular spaces lined by a single layer of endothelial cells. Tumor cells with oval nuclei and eosinophilic cytoplasm were observed in the periphery of the endothelial cells, forming one to several layers. Immunohistochemical studies showed the tumor cells to be positively stained with antibodies to α-smooth muscle actin and vimentin but not with the antibody to desmin, myosin, or S-100 protein. The endothelial cells were positively stained with antibody to factor VIII-related antigens. These results therefore support the concept that glomus tumors originate from vascular smooth muscle cells.
