A rare tumor with atypical location: Schwannoma of the ulnar nerve - case study

Abstract

Schwannomas are rare benign tumors. Their location on the ulnar nerve is particularly uncommon in young adults. We present the case of a 22-year-old male who was followed for a progressively developing painful mass on the medial aspect of his left arm, associated with sensory disturbances that evolved toward early muscle atrophy in the hypothenar compartment. MRI revealed a well-defined mass within the sheath of the ulnar nerve. Complete surgical excision was performed. Histopathological examination confirmed the schwannomatous nature of the tumor. At the latest follow-up, the patient showed complete functional recovery without recurrence of pain or residual sensory disturbances. Untreated ulnar nerve schwannomas can lead to pain, paresthesia, and motor deficits due to chronic compression. Diagnosis relies on the triad of clinical evaluation, imaging, and histological confirmation. Despite their rarity, schwannomas should be systematically considered in the differential diagnosis of any upper limb mass presenting with neurological signs.