Malignant Glomus Tumors of the Stomach: A Report of 2 Cases with Multiple Metastases

ABSTRACT

Glomus tumors are mesenchymal neoplasms usually developing in the dermis or subcutis of the extremities. The majority of glomus tumors are entirely benign, and malignant glomus tumors are very rare, especially those arising in the visceral organs. Here, we are presenting two cases of malignant glomus tumor, initially diagnosed in the stomach by endoscopic biopsy. Case 1 was found in the stomach, right kidney, brain and humerus of a 65-year-old woman, and Case 2 in the stomach and liver of a 63-year-old man. Histologically, the tumor was composed of solid sheets and nests of round and short-spindle shaped tumor cells with vesicular nucleus and prominent nucleolus. The tumor cells were closely admixed with blood vessels of varying size. Immunohistochemically, the tumor cells showed diffuse and strong positive staining for smooth muscle actin and paranuclear, dot-like staining for synaptophysin, but negative for desmin, c-kit, CD34 and S-100 protein. These two are rare cases of a malignant glomus tumor with widespread metastases.