[Clinicopathologic characteristics of hemangiopericytoma/solitary fibrous tumor with giant cells].

OBJECTIVE: To study the pathological characteristics, diagnosis and differential diagnoses of hemangiopericytoma-solitary fibrous tumor with giant cells. METHODS: Pathological characteristics of seven cases of orbital and extraorbital hemangiopericytoma-solitary fibrous tumors with giant cells were evaluated by HE and immunohistochemistry (EnVision method). RESULTS: Two cases were located in the orbit, one of which had recurred. Five cases were located in the extraorbital regions. Histologically, the tumors were well-circumscribed and composed of non-atypical, round to spindle cells with collagen deposition in the stroma. The tumors had prominent vasculatures and in areas, pseudovascular spaces lined by multinucleated giant cells lining which were also present in the stroma. Immunohistochemically, both neoplastic cells and multinucleate giant cells expressed CD34. Seven patients underwent tumor excision and were well and without tumor recurrence upon the clinical follow-up. CONCLUSIONS: Hemangiopericytoma-solitary fibrous tumor with giant cells is an intermediate soft tissue tumor. It typically involves the orbital or extraorbital regions. Histologically, the tumor should be distinguished from giant cell fibroblastoma, pleomorphic hyalinzing angiectatic tumor of soft part and angiomatoid fibrous histiocytoma.