72 year old male without any significant past medical history presented with right groin soft tissue mass, measuring 12 x 9 x 7 cm. There was no connection to the underlying bone, but the mass had ruptured anteriorly into the subcutaneous compartment of the anterior thigh. The tumor cells were positive for WT1 (strong, diffuse) and CD99 (patchy), and negative for keratin, desmin, S100, Melan A, HMB45, PAX5, MUM1, CD43, TLE-1 and OCT4. SMARCB1 (INI-1) is reatained. Fluorescence in situ hybridization (FISH) studies failed to show EWSR1 rearrangement, and RT-PCR did not reveal EWSR1-FLI1 or EWSR1-ERG fusion transcripts.
|Suvra Roy, M.B.B.S.
Fellow, Surgical Pathology
|Karen Fritchie, M.D.
Consultant, Anatomic Pathology
Associate Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine