Perineural Lipoma of the Ulnar Nerve Within the Cubital Tunnel: A Brief Review of the Literature

This study presents a case of a patient with a 6-month history of progressively worsening paresthesia, numbness, weakness, and shooting pain in the ulnar nerve distribution of the left hand. Ultrasound measurements showed an enlarged cross-sectional area of the ulnar nerve, confirming the diagnosis, and an isoechogenic and homogenous mass alongside the ulnar nerve. An open cubital tunnel release was performed for ulnar nerve decompression. Intraoperatively, a perineural lipoma was identified within the cubital tunnel and subsequently confirmed by histopathological analysis. Soft tissue lipomas rarely cause symptomatic compressive neuropathy. Although other space-occupying lesions within the cubital tunnel are well-documented in the literature, a perineural lipoma causing extrinsic ulnar nerve compression has not been previously reported. After surgery, shooting pain resolved, sensation normalized in digits four and five, and hand strength gradually improved. Therefore, we report the first case of a perineural lipoma extrinsically causing ulnar nerve compression in the cubital tunnel.