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Washington University Experience | NEOPLASMS (MESENCHYMAL, NON-MENINGOTHELIAL) | Solitary Fibrous Tumor (SFT) | 1H HAP-SFT, WHO 3 (Case 1) Ki67 1
Ki67 (MIB-1 antibody) highlights a proliferation index that focally reaches 15-20%. ---- Ancillary studies (not shown): The tumor cells are positive for vimentin (diffuse in hypercellular areas, patchy in myxoid areas), CD99 (patchy throughout), and SMA (patchy throughout). Tumor cells are negative for EMA, S-100, desmin, pancytokeratin (AE1/AE3), GFAP, Olig2, and PAX-8. Reticulin is rich, especially in the hypercellular areas. A PAS stain highlights the myxoid areas, which is lost with the addition of diastase (PAS-D), evidence for the presence of significant glycogen
Fluorescence in situ hybridization for EWSR1 and DDIT3 break apart probes show no evidence of rearrangement. ---- Comment: The presence of a mitotic rate ≥ 5 mitoses/10HPF in the absence of necrosis is consistent with a diagnosis of SFT, WHO Grade 2.
