Musculoskeletal hemangiopericytomas are a location specific subtype of hemangiopericytomas.
These tumors are most frequently seen in middle-aged adults (~ 4th decade).
In the case of hemangiopericytomas, they arise from the cells of Zimmerman, which surround vessels. Both benign and malignant forms are encountered.
Typically they have large vessels especially located at its periphery, and commonly involve the lower limbs (35% of cases), especially the thigh, pelvis and retroperitoneum (25%). Primary osseous lesions are rare.
Radiologically they appear the same as angiosarcomas and hemangioendotheliomas.
Nonspecific soft tissue mass. When involving bone, they are predominantly lytic, and may mimic hemangiomas with a course honeycomb appearance.
Dense, well-circumscribed areas of enhancement with early draining veins and shunting. Hemangiopericytoma are described as having a pedicle formed by the arteries supplying the tumor from which vessels branch to encircle the tumor.
Nonspecific soft tissue mass, with a density similar to muscle but demonstrating bright contrast enhancement. CTA may demonstrate large feeding vessels.
Brightly enhancing soft tissue mass, often hyperintense on T2WI, with prominent flow voids, most marked in hemangiopericytomas.