A case of bilateral extensor digitorum brevis manus.

We report a case of symptomatic dorsal mass in a 72-year-old man, with onset of pain during daily life efforts. On the other side, the dominant hand, a similar mass without any impairment was present. Before surgery, the mass on the left nondominant wrist was diagnosed by ultrasound as synovial ganglion: during excision, a muscular belly was found and sent to isthological evaluation, confirming the existence of an alive aberrant muscular tissue, named Extensor Digitorum Brevis Manus.