Carpal tunnel syndrome revealing a fibrolipoma of the median nerve

Abstract

A 25-year-old man presented with a 3-month history of sensory disturbance affecting the three radial digits and the lateral half of the ring finger of his right hand. He reported nocturnal numbness and tingling in the hand’s median nerve territory. He was a military soldier with no medical history. Physical examination showed elastic soft tissue mass in the volar surface of his right wrist (Fig. 1a). Tinel’s sign and Phalen’s test were positive. There was no atrophy of the thenar eminence. Ultrasonography of the right wrist revealed a fusiform enlargement of the median nerve containing parallel hypoechoic bands on longitudinal images and dots on transverse images consistent with nerve fibers separated by hyperechoic substratum consistent with fatty infiltration (Fig. 1b). Magnetic resonance imaging (MRI) showed a fat-intensity signal fusiform mass that appeared as high signal intensity on T1and T2-weighted images and low signal intensity on fat-suppressed T2-weighted images surrounding nerve fascicles (Fig. 1c and d). No contrast enhancement was seen after gadolinium administration. The diagnosis of carpal tunnel syndrome secondary to a fibrolipoma of the median nerve was made based on clinical and imaging features. The patient had neurolysis and decompression of the median nerve. Histopathological examination of a perineurium biopsy specimen revealed infiltration of perineurium with mature fibrous and adipose tissue (Fig. 2). The patient reported a complete resolution of his symptoms and remained asymptomatic after 3 months of treatment.