Clinicopathologic and immunohistochemical characteristics of 8 cases of solitary fibrous tumor

Objective To study the clinicopathologic and immunohistochemical features of solitary fibrous tumor (SFT) and its biologic behavior. Methods Clinicopathologic data of 8 cases of SFT were collected and analyzed. Immunohistochemical staining (Envision method) for CD34, vimentin, CD99, bcl-2, S-100 and SMA was performed in the specimens collected from January 2003 to June 2006 in our hospital. Results Eight patients, 5 male and 3 female, aged from 31 and 62 years (mean 45.3). SFTs located in mediastinum, nasal cavity, parotid, oral cavity and orbital cavity. The main clinical manifestations were local mass and pressure symptom. The diameter of SFTs was between 1.5 cm and 25.0 cm and clear edge in most SFTs. The characteristic features under microscope included patternless growth pattern, alternating hypercellular and hypocellular areas, blunt spindle cells within keloidlike hyalinization, and hemangiopericytoma-like regions. Positive immunohistochemical staining was vimentin 8, CD34 7, bcl-2 6, CD99 7, SMA 4, S-100 1. Conclusion SFT is a rare mesenchymal spindle cell tumor, occurring in various parts of human body. It needs to be distinguished from other spindle cell tumors, and the immunophenotype can be of help in differential diagnosis. Minority of SFTs has malignant behavior, manifesting as local recurrence or metastasis. The behavior of SFT is unpredictable, requiring a careful, long-term follow-up.