Posterior interosseous nerve syndrome due to intramuscular lipoma
A 48-year-old woman presented with spontaneous inability to extend the fingers of the left hand. She noticed a gradually increasing inability to extend the fingers over 6 months. She was unable to perform her domestic activities because of weakness and paresis of the hand; she denied any trauma or other diseases. Examination revealed a swelling of 5 × 3 cm in the anterolateral aspect of the left forearm in the region of the brachioradialis muscle just below the elbow. The swelling was firm in consistency, immobile, not fixed to the skin; there were no dilated veins over the swelling or signs of inflammation. The elbow function was normal, as was the flexor strength of the wrist and fingers; however, there was a decrease in the extension strength of the wrist and metacarpophalangeal joints of the fingers and thumb (power 3/5). There was no sensory deficit. Magnetic resonance imaging of the elbow objectified an intramuscular mass, of 8-cm-long axis depending on the supinator muscle, pathognomonic of a lipoma (Figs. and ). Surgical excision was recommended. General anesthesia was administered, and an incision was made over the mass. The incision of the supinator muscle exposed a fatty encapsulated mass (Fig. ). The dissection of the mass revealed that it is constricting the PIN (Figs. and ). The nerves were carefully released, and a lipoma was removed. The PIN was preserved, without damage (Fig. ). Histological examination of the tumor confirmed it to be a benign lipoma (Figs. and ). In the early postoperative period, the radial nerve recovered its function. A physiotherapy program was started 2 weeks after surgery. The patient recovered well, and 6 weeks after surgery, she resumed her activities. No local recurrence was detected at 18 months after surgery.