Malignant glomus tumor of the palm: a case report.

The author herein reports on a glomus tumor of the palm. A 71-year-old man consulted our hospital because of a tumor on the left palm. The tumor was deeply seated, and MRI and CT showed a deep cystic tumor adjacent to the bone. An excision of the tumor was therefore performed. Grossly, the tumor was red and partly cystic. The tumor was well defined from the surrounding tissues, and measured 25 × 24 × 22 mm. Microscopically, the tumor consisted of epithelioid perivascular cells (glomus cells) located around the blood vessels. Cystic changes and hyalinization areas were scattered. The tumor cells had moderately hyperchromatic nuclei. Nuclear pleomorphism was noticed, nucleoli were absent and apparent mitotic figures were not recognized. There were no areas of necrosis. Immunohistochemically, the glomus cells were positive for vimentin and α-smooth muscle actin. They were negative for cytokeratins, epithelial membrane antigen, CD34, CD31, factor VIII-related antigen, S100 protein, p53 protein, desmin and melanosome. The Ki-67 labeling was 5%. The tumor was diagnosed as a malignant glomus tumor because of its deep location and size > 2 cm , according to the criteria of one group. The tumor recurred 12 months later, and a further excision was performed. No metastases were found. Now, the patient is being strictly followed up.