Posterior interosseous nerve syndrome caused by an intermuscular lipoma

The posterior interosseous nerve is prone to entrapment at various anatomical sites along its course in the upper forearm. A variety of lesions may account for this resulting nerve palsy. Compression of the nerve by lipomata is uncommon; 16 such cases have been reported in the medical literature. We present a case of a lipoma causing pressure on the deep branch of the radial nerve. In this case, and in seven similar cases previously reported in detail, the mass became visible after the onset of finger and hand extensor muscle weakness. Hence, the possibility of nerve compression by a tumor must be suspected in the differential diagnosis. Paralysis that does not respond to four to six weeks of conservative treatment necessitates surgical intervention in order to assure maximum recovery of the affected nerve.