Delayed diagnosed posterior interosseous nerve palsy due to intramuscular myxoma.

We present a case of posterior interosseous nerve palsy after bowel surgery associated with intramuscular myxoma of the supinator muscle. The initial symptoms of swelling of the forearm made it difficult to distinguish the condition from extravasations after intravenous cannulation. The diagnosis was finally established with nerve conduction studies and MRI 3 months after symptom onset. The patient underwent surgery for removal of the tumour and decompression of the posterior interosseous nerve. The histological examination identified the tumour as intramuscular myxoma and the patient made a full recovery with no recurrence of the lesion until present. Every swelling on the forearm causing neurological disorders is tumour suspected and should be examined clinically as well as electrophysically and radiographically. Early surgery and nerve decompression should follow immediately after the diagnosis. In case of intramuscular myxoma, good recovery of function after surgery with low recurrence risk may be expected.