30-year-old female with history of recurrent left upper extremity AV malformation. Large lesion with extensive infiltrating signal abnormality and enhancement is seen predominantly within the extensor musculature of the proximal and mid forearm, including extensor digitorum, extensor carpi ulnaris, and extensor digitorum minimi. The lesion also involves anconeus muscle, supinator muscle, extensor pollicis longus, and abductor pollicis longus. The lesion extends across the interosseous membrane to mildly enter the anterior compartment. The lesion is predominantly high in T2 signal and T1 isointense to skeletal muscle with peripheral and septal fat signal seen. Scattered low signal intensity rounded foci within the lesion are presumably related to phleboliths, as seen on prior CTA. Overall, this lesion compatible with venous malformation ("hemangioma"). Prominent vasculature is seen within the proximal ulnar diaphysis, indicating intraosseous involvement, with involvement of the proximal radial diaphysis to a lesser degree. Overall, the lesion measures up to 5.5 x 4.5 cm in transverse dimension and 16 cm in longitudinal dimension.Additional smaller infiltrating lesion is seen in the distal forearm soft tissues just proximal to the wrist predominantly within the pronator quadratus muscle with the lesion seen crossing the interosseous membrane to enter the dorsal compartment beneath the extensor digitorum tendons. This lesion measures up to 3.5 x 2.5 cm in transverse dimension and 3.5 cm in longitudinal dimension. This lesion has similar signal characteristics but with no significant bone involvement.Prominent vessels are noted within the subcutaneous fat along the dorsum of the wrist, as well as in the subcutaneous fat in the lateral aspect of the forearm, most compatible with draining vessels. Signal void is seen at the dorsal aspect of the wrist and in the lateral soft tissues of the forearm, presumably related to surgical change.No edema-like signal is seen adjacent to the lesions to suggest infection or inflammation. No evidence of soft tissue abscess. No acute fracture or malalignment.
Extensive venous malformation ("hemangiomata") of the left forearm as detailed above and similar to prior CTA. No acute abnormality is evident.