Fibrolipomatous Hamartoma of the Median Nerve of the Hand: A Case Report and Literature Review

Introduction: Fibrolipomatous Hamartoma (FLH) is a rare tumor-like disease, mainly occurs in benign tumors of the peripheral nerves of the upper limbs, which characterized by the overgrowth of neuronal fat and fibrous tissue. Case presentation: A patient had numbness of fingers in the left hand for more than 5 years. Three years ago, the superficial sensation at the metacarpophalangeal joint of the hypothenar of the left hand was weakened. Two years later, the distal ulnar side of the index finger and the distal radial side of the middle finger were secondary to weakened superficial sensation and megalodactyly symptoms of the middle finger and index finger of the left hand were developed. Physical examination showed a mass on the left palm side. MRI showed an abnormal subcutaneous fusiform signal at the palmar side of the left wrist: T1W1 isointensity, T2W1 inhomogeneous slightly hyperintense signal. The clinical features, radiologic presentations, treatment choice, and pathologic characteristic were illustrated. During the operation, the appearance of the nerve was hypertrophic and variant, without obvious masses, the proliferated fibrous tissues were showed a fusiform change, and the nerve fibers were degenerated and atrophied. Immunohistochemical results showed S-100 (+), NSE (focus +), EMA (portion +), GFAP (-), ERG (blood vessel +), SMA (blood vessel +), Ki-67 (1%+), NF (small region +). The patient's finger numbness symptom improved obviously and the condition was stable when paying a return visit 3 months after the operation. Conclusions: ： The clinical symptoms of FLH of median nerve mainly include gradually enlarged painless mass, macrodactyly, pain, numbness, paresthesia and carpal tunnel syndrome. The diagnosis mainly depends on ultrasonic examination and MRI. The pathological sections of FLH sometimes show perineurioma-like changes, which need to be identified by clinical and MRI features. The treatment methods include prophylactic carpal tunnel release (CTR) and nerve transplantation after the whole nerve resection. CTR, has been proven to be helpful for many patients suffering from carpal tunnel symptoms and can relieve most of the symptoms, is the main method. However, the pathogeny needs to be further explored.