Fig. 20

Fibrosarcoma of the tendon sheath in a 47-year-old female presenting with focal swelling along the ulna aspect of the right wrist, gradually increasing in size over a few months. (a) Ultrasound shows a well-defined hypoechoeic lesion along the ulnar side of the wrist abutting the extensor carpi ulnaris (arrow). (b) T1w sequence shows a hypointense well-circumscribed subcutaneous lesion abutting the extensor carpi ulnaris (arrow). (c) The lesion is predominantly of low signal on T2w sequence, with small areas of high signal (arrow) indicating a more cellular/necrotic component. (d) Heterogeneous enhancement is seen, in contrast to a benign FTS (Fig. 3), which shows only minimal enhancement