Lipofibromatous hamartoma of the median nerve in patients with macrodactyly: diagnosis and treatment of a rare disease causing carpal tunnel syndrome.

Lipofibromatous hamartoma is a very rare benign peripheral nerve tumour. It is mostly encountered in the proximal extremities of young adults, involving the median nerve in the majority of cases. We present two patients with macrodactyly and carpal tunnel syndrome caused by lipofibromatous hamartoma of the median nerve and discuss diagnosis and treatment of the disease. A 10-year-old girl with a congenital progressive macrodactyly of her right index finger presented with a slowly growing mass in her right palm and pain and numbness, along with motor and sensory deficits in the median nerve distribution. Treatment consisted of carpal tunnel release, epineurolysis and partial excision of the fibrofatty tissue. The second patient, a 25-year-old man presented with a swelling in his left palm and findings compatible with carpal tunnel syndrome. Intraoperatively, the lesion presented as sausage-shaped enlargement of the median nerve by fibrofatty tissue. After carpal tunnel release, a partial excision of the mass with epineurolysis was performed. In both patients, histology showed nerve bundles separated by abundant fibrofatty tissue. In the girl, a proliferation of dysplastic perineurial cells could be observed. The suspected diagnosis for patients with macrodactyly and clinical signs of carpal tunnel syndrome should be lipofibromatous hamartoma. A carefully taken history, physical examination, X-ray, and MRI are important for its correct diagnosis. The surgical management remains controversial. Treatment should include decompression of the median nerve at points of compression, partial excision of the fibrofatty tissue, and debulking of soft tissue. In some cases, an epineurolysis can be additionally performed.