Ultrasonographic Diagnosis of Lipomatosis of Nerve: A Review of Ultrasonographic Finding for 8 Cases

Lipomatosis of nerve (LN) is a rare tumor-like condition with epineural and perineural infiltration by adipose and fibrous tissue. The purpose was to analyze the ultrasonographic findings of LN involving upper limb peripheral nerves.This was a retrospective analysis of a series of 8 patients with LN involving upper-limb peripheral nerves between 2013 and 2019. All patients underwent preoperative ultrasonography for the upper-extremity nerves and were diagnosed as LN by surgery. The clinical manifestations, ultrasonography characteristics, and accuracy were analyzed.In this series, LN was involved in 10 peripheral nerves from 8 patients. The median nerve was the most commonly affected nerve (60%). Four cases presented macrodactyly combined with masses from distal forearm and extending to wrist and palm areas. Among 8 patients, 5 cases were diagnosed with LN by preoperative ultrasonography, an accuracy of 62.5%. Axial ultrasonic imaging showed the punctate hypoechoic fascicles was embedded in hyperechoic adipose tissue in the "lotus root-like" appearance; longitudinal ultrasonic imaging showed the strip hypoechoic fascicles alternates with hyperechoic adipose tissue in the "cable-like" appearance. Meanwhile, ultrasonic imaging showed the thickened of adipose tissue around the affected nerve and the enlargement of flexor tendons in some patients.Ultrasonography has the potential to be a useful tool for the noninvasive examination of LN. The possibility of LN should be considered in patients with a mass in wrist and palm, macrodactyly, or syndactyly. Our finding may benefit the preoperative differential diagnosis with common nerve tumors.