Thumb mass Within the thenar eminence is a solid lobulated, ovoid mass which is predominantly hyperintense to musculature on T2 and iso to slightly hyperintense on T1. The mass measures approximately 2 x 1 x 2.9 cm in the greatest transaxial and craniocaudal dimensions. Additionally, more radially and anterior to the thumb are additional subcentimeter foci which demonstrate similar signal characteristics. The dominant mass causes some displacement of the flexor tendons and median nerve and there is a mild amount of surrounding subcutaneous edema. The mass also appears to be discrete from the median nerve.Following contrast administration, there is predominantly heterogeneous enhancement within more focal area distally demonstrating more peripheral enhancement (series 13 image 42/64 and series 16 image 20/36).The remaining muscles and osseous structures are normal in signal and caliber.
Solid lobulated mass within the thenar eminence demonstrates nonspecific imaging characteristics. As a result, both benign and malignant etiologies must be considered including epithelioid sarcoma. This mass would be amenable to ultrasound-guided biopsy.