Granular cell tumor of the cecum with extensive hyalinization and calcification: a case report.

A granular cell tumor (GCT) is a benign neoplasm of unclear histogenesis that is generally believed to be of nerve sheath origin. GCT is not common and most often affects the tongue, skin and soft tissue, although it may occur anywhere in the body. We experienced a case of GCT that arose in the cecum of a 55-year-old man. The GCT was removed by laparoscopic resection. In addition to the tumor, endoscopic examination revealed the presence of a 5-mm-polyp in the descending colon and multiple tiny polyps in the sigmoid colon and rectum. Histological examination demonstrated a cecal tumor 1.5 cm x 1.0 cm x 0.7 cm with a hard consistency; in cut sections, mixed cells with yellowish and whitish portions were seen. The tumor was located between the mucosa and subserosa, and was composed of plump histiocyte-like tumor cells with abundant granular eosinophilic cytoplasm, which were immunoreactive for S-100 protein, vimentin, neuron-specific enolase, inhibin-alpha and calretinin. The tumor showed extensive hyalinization and focal dystrophic calcification. Immunohistochemical profiles did not confirm any particular cell type for the histogenetic origin of the GCT, including a nerve sheath origin. Extensive hyalinization and calcification showing involution of tumor cells suggest benign clinical behavior of GCT.