Ossifying fibrolipomatous hamartoma of the ulnar nerve.

An ossified fibrolipomatous epineural hamartoma limited to the right ulnar nerve and some of its branches and extending from the elbow distally is described in a 5-year-old boy who complained of pain in the right hand. Such extensive involvement of the ulnar nerve is unusual; moreover, metaplastic bone is rarely present in the more common fibrolipomatous hamartoma of the median nerve. Increased awareness of this entity is necessary to avoid sacrifice of large nerves that may be included in the lesion.