ABSTRACT
Purpose To investigate the clinicopathologic characteristics, diagnosis, differential diagnosis and prognosis of malignant solitary fibrous tumor/hemangiopericytoma ( SFT/HPC). Methods Sixteen cases of intracranial malignant SFT/HPC were retrospectively studied. The clinical data, imaging features, histopathological and immunohistochemical characteris-tics were analyzed. Results The 8 male and 8 female patients were between 31 and 71 years of age ( mean 51). The median age was 51 years (range, 31-71 years). 16 malignant SFT/HPC cases were originated from intracalvarium. The imaging features showed intracranial neoplasms with relatively clear surrounding boundaries. Microscopically spindle shaped cells were hypercel-lular, and exhibited≥5 mitoses per 10 HPF. Cytological atypia was mild. The clinicopathologic characteristics included pattern-less growth pattern, storiform or fascicular growth pattern, solita-ry fibrous tumor-like regions and hemangiopericytoma-like re-gions. Tnere were 2 cases with abundant papillary structure and 2 with sarcomatous structure, 2 with focal necrosis, 2 with inva-ded cerebral tissues, and 10 with invaded meninges. Immuno-histochemically, 93. 75% ( 15/16 ) cases were positive for STAT6, with 15/16 showing diffuse staining. 87. 5% (14/16) cases were positive for CD34, with 37. 5% (6/16) showing dif-fuse staining. 81. 25% (13/16) cases were positive for BCL-2. 68. 75% (11/16) cases were positive for CD99. The Ki-67 in-dex ranged from 5% to 40% . Sixteen patients were followed up for 1-64 months, and 7 patients ( 43. 75% ) had recurrences. Conclusion Malignant SFT/HPC shares malignant behaviours. STAT6 is a specific marker for the diagnosis of this tumor. The prognosis of malignant SFT/HPC is related to the extent of tumor excision and long-term follow-up.