An Epidermoid Cyst along the Sensory Branch of Digital Nerve with Focal Neuropathy: A Case Report

Abstract

An epidermoid cyst is a slow-growing benign neoplasm that commonly occurs in the hand. Herein, we report a rare case of an epidermoid cyst with focal neuropathy in the left ring finger of a 38-year-old woman. Preoperatively, the patient complained of erythema, swelling, and paresthesia on her fingertips. On ultrasonography and magnetic resonance imaging, ulnar digital nerve thickening and inflammation around the nerve were observed, and a neurogenic tumor-like schwannoma was expected. An excisional biopsy with neurectomy of the involved sensory branch of the ulnar digital nerve was performed under brachial plexus block. During the operation, there is such an uncommon morphology, yellowish debris under the epineurium of the ulnar digital nerve sensory branch was involved with the epidermoid cyst and seemed to be propagating along the sensory branch from the skin surface. After the operation, the paresthesia and swelling resolved. Over the 6-month follow-up in the outpatient clinic, no complications and recurrences occurred. Thus, we reported a rare intraneural epidermoid cyst (occurred along the digital nerve) in the finger, and we believe that considering the anatomical characteristics and the surrounding structures is important during mass excision.