Ulnar Neuropathy Caused by a Giant Epidermal Cyst at the Elbow: Case Report

Here, we report an unusual case of ulnar neuropathy at the elbow caused by a giant epidermal cyst. A 76-year-old man was assessed on an outpatient basis for ulnar numbness of the left hand that had persisted for 6 months. A soft, elastic subcutaneous mass 6 cm in size was noted on his left elbow. He felt numbness on the ulnar aspect of the left fourth and fifth fingers, corresponding to the area innervated by the ulnar nerve, which worsened upon elbow flexion. An electrophysiological study revealed ulnar neuropathy at the elbow. To remove the subcutaneous mass at the left elbow and open up the ulnar tunnel, surgery was performed. There were no signs of nerve impingement or a neuroma on the ulnar nerve. The histological diagnosis was an epidermal cyst. On the day after surgery, numbness on the ulnar aspect of the left hand upon elbow flexion was markedly abated.