2064. Imaging of Epithelioid Sarcoma with Pathologic Correlation
Authors* Denotes Presenting Author
Stephen Savioli *;
MedStar Washington Hospital Center
This study aims to evaluate the radiologic appearance of epithelioid sarcoma with pathologic correlation.
Materials and Methods:
Twenty pathologically confirmed cases of proximal and distal subtypes of epithelioid sarcoma were retrospectively reviewed. Radiologic studies were independently reviewed by three musculoskeletal radiologists, with agreement by consensus and included radiographs (n=3), ultrasonography (n=3), PET/CT (n=4), CT (n=9), and MRI (n= 16). Evaluation included patient history and demographics, lesion size and location, and intrinsic imaging characteristics on ultrasound, CT, and MRI.
Average patient age was 34 years old, with male predominance (80%). Symptoms including pain, swelling, or an enlarging mass were present in 50% of patients. All distal and proximal lesions had increased uptake on PET/CT.
All patients with distal lesions presented with skin ulceration of an extremity. Radiographs demonstrated nonspecific soft tissue masses (67%) without calcifications (100%). On MRI, all distal lesions were multifocal and showed infiltrative margins, with underlying bone involvement. All distal lesions demonstrated T1 signal isointense to muscle, and intermediate signal on T2-weighted sequences.
Proximal tumors were solitary and most commonly found in the buttocks or pelvis (50%). The average lesion measured 7.1 cm. Sonograms demonstrated masses with heterogeneous echogenicity (100%). On CT, all tumors were isodense to muscle, and well defined (89%). No calcifications were seen on CT. On MRI, lesions were well-defined (100%) with intermediate signal on both T1- and T2-weighted images. Unlike distal lesions, bone involvement with erosion was unusual (11%). There was only mild surrounding edema in 33% of cases.
The imaging appearance of epithelioid sarcoma varies on the lesion subtype, either distal or proximal. Distal lesions have a suggestive imaging appearance of multifocal subcutaneous lesions with infiltrative margins, bone involvement, and associated surrounding edema. In contradistinction, proximal lesions have a nonspecific imaging appearance of a well-defined soft tissue mass without intrinsic features to suggest diagnosis.