The finding of a tumor consisting of striated muscles and fibrous connective tissue attached to the dorsal side of the facial nerve sheath located in the cavity of the pyramidal portion of the canalis facialis is described. The observation was made when the facial nerves of three patients were exposed during the surgical treatment for Bell's palsy.
The finding is interpreted as dystopy due to the deviation in the common development of the facial nerve and facial muscles. Other clinical aspects are pointed out.