Mass in forearm Note that a marker was placed along the volar aspect of the midforearm in the region of the patient's mass. There is an irregularly-marginated mass within the underlying subcutaneous fat of the volar forearm that contacts the underlying deep peripheral fascia of the anterior compartment musculature. This mass extends to the skin with the overlying skin appearing thickened. It measures approximately 3 x 1 cm in the transverse dimensions and just over 5 cm in the longitudinal dimension. The mass demonstrates irregular and spiculated margins and is slightly hyperintense to muscle on T1, hyperintense to muscle on T2, and shows diffuse enhancement following gadolinium administration. There is subcutaneous edema extending along the fascia both proximal and distal from the mass over the majority of the length of the forearm. The mass does not infiltrate the underlying musculature. The muscles of the forearm are normal in caliber and signal and the marrow signal of the radius and ulna is also normal. There is mild edema and enhancement of the subcutaneous fat posterior to the olecranon which may reflect mild inflammation.
Irregularly-marginated mass within the volar subcutaneous fat of the forearm. While a specific histologic diagnosis cannot be ascertained, the location and characteristics are suggestive of nodular fasciitis. Referral to orthopedic oncology is recommended.