Glomus tumor of the crissum: A case report and review of literature.

Glomus tumor is a rare mesenchymal neoplasm arising from the modified smooth muscle cells of the glomus body. Primary crissum glomus tumor is extremely rare without any published in the literature. In this article, we report the first case of primary crissum glomus tumor in an 80-year-old man with recurrent anal pain for 8 years, increased pain for 1 year. Rectal MRI for inflammatory lesions (sinus tract). Microscopic examination showed the tumor cells were arranged in sheets and nests, surrounding blood vessels and nerve bundles. At high magnification, the neoplastic cells show regular round shape with light eosinophilic and translucent cytoplasm. The cell boundary is clear, the nucleus is round and located in the center. The stroma of the tumor shows hyaline degeneration. Immunohistochemically, the tumor cells were positive for smooth muscle actin, h-caldesmon, Calponin, synaptophysin, Collagen IV and CD34, but completely negative for HMB45, S100, EMA, desmin, CgA and CD56. The histologic features and immunohistochemical profile supported a diagnosis of primary crissum glomus tumor. The patient was asymptomatic and disease free after the procedure.