[Clinicopathologic characteristics of myopericytoma].

Objective: To investigate the clinicopathologic characteristics and differential diagnosis of myopericytoma.

Methods: Six cases of myopericytomas were analyzed by light microscopy and immunohistochemistry (LSAB detection method).

Results: Tumors from 3 females and 3 males were found on the extremities and chest wall. The ages of these 6 patients ranged from 16 to 58 years. Histologically, all tumors were unencapsulated. The neoplastic cells were oval to spindle shaped with eosinophilic cytoplasm, had a myoid appearance and showd areas of concentric perivascular proliferation around lesional blood vessels which were present with focal myxoid stroma. Morphologically in some cases the tumor overlap myofibroma, hemangiopericytoma or glomus tumor. One tumor was located entirely within the lumen of a vein. In another case, the tumor displayed cellular pleomorphism, mitotic activity, necrosis should be diagnosed as malignant myopericytoma. The neoplastic cells were positive for SMA and negative for CD31, CD34, S-100, and CK.

Conclusions: Myopericytoma is composed of oval to spindle shaped myoid cells with a striking tendeny for concentric perivascular growth. These cells differentiate towards perivascular myoid cells or myopericytes. Extremely rare malignant myopericytoma exist.