Presentation
Left distal forearm-wrist volar region lump for the previous few months. Gradually increasing in size. Recent onset of 4th, and 5th finger mild weakness. No trauma/ prior surgery.
Patient Data
The clinically visible lesion is a well-defined echogenic lesion with internal striations without calcification/ cystic changes/ vascularity. Mildly compressible lesion measuring 65 (length) x (width) x 10 (anteroposterior) mm. It is located in the distal forearm ulnar volar side, passes through Guyon's canal, and reaches the hypothenar region. It is located in the ulnar nerve just distal to the dorsal cutaneous branch origin. The lesion splays the ulnar nerve fascicles into three bundles, one being a deep branch, the second being a common branch to adjacent sides of the 4th and 5th fingers, and the third being the ulnar side digital branch of the 5th finger.
An elongated well-defined fat density over the distal ulna. The oblique view shows that the density passes distal to the pisiform bone. No abnormality involving the wrist joint. Mild joint space reduction of the visible interphalangeal joints.
Fatty lesion separating the ulnar nerve into three bundles.
Case Discussion
The case shows a lipoma in the ulnar nerve. Surgical excision was done. The histopathology of the lesion was a lipoma.
Lipoma is the most common soft tissue tumor. However, a lipoma in a nerve is an uncommon location. This pathology is different from the lipomatosis of the nerve.
Intraoperative photo courtesy: operating surgeon Dr Pinkesh V. Patel