Myopericytoma

Myopericytoma is a rare benign soft tissue tumor that arises from perivascular myoid cells (pericytes), which are cells that normally surround small blood vessels. This tumor belongs to the family of perivascular tumors, which also includes myofibroma and glomus tumors. Myopericytomas most commonly present as a slow-growing, painless, well-circumscribed nodule in the subcutaneous tissue or dermis of the extremities, particularly the lower limbs. They can also occur in other locations including the head, neck, and trunk. The tumors are typically solitary, although rare cases of multifocal myopericytomas have been reported. Histologically, myopericytomas are characterized by a concentric perivascular proliferation of oval to spindle-shaped myoid cells arranged around thin-walled blood vessels. The tumor cells express smooth muscle actin, reflecting their pericytic origin. While the vast majority of myopericytomas are benign, exceedingly rare malignant variants have been described in the literature, which may exhibit infiltrative growth, nuclear atypia, increased mitotic activity, and potential for metastasis. The primary treatment for myopericytoma is complete surgical excision, which is generally curative for benign lesions. Local recurrence is uncommon after adequate resection. No specific systemic therapy is typically required for benign myopericytomas. For the rare malignant cases, wider excision and close follow-up are recommended, though standardized treatment protocols are lacking due to the extreme rarity of malignant transformation. Prognosis for typical benign myopericytoma is excellent.

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