Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 3, 2011, pp. 488-489

Neurology India, Vol. 59, No. 3, May-June, 2011, pp. 488-489

Neuroimage

Imaging of neurofibrolipoma of median nerve

N Diwakar, Ravindra B Kamble, Mallinath Gidaganti

Department of Radiology and Orthopedics, BGS Global Hospital, Uttarahalli Road, Kengeri, Bangalore, Karnataka, India

Correspondence Address: Ravindra B Kamble Department of Radiology, BGS Global Hospital, Uttarahalli Road, Kengeri, Bangalore India vdrravindra31@rediffmail.com

Code Number: ni11147

PMID: 21743200

DOI: 10.4103/0028-3886.82767

A 30 year old woman presented with gradual swelling over the volar aspect of left wrist and hand of 10 year duration. She had complaints of pain and paresthesia on volar aspect of hand involving fingers. On examination there was mild atrophy of hypothenar muscles and sensory deficits in the medial three and half fingers. All the blood investigations were normal. She was not a known case of diabetes or hypertension. She was referred for further investigations. Ultrasound examination showed welldefined fusiform echogenic lesion in the wrist extending to hypothenar region below the flexor retinaculum without any surrounding infiltration with hypoechoic linear structures within. Median nerve was not seen separately [Figure - 1]. Subsequent magnetic resonance imaging (MRI) showed a mass lesion, fusiform enlargement of the median nerve just proximal to wrist and extending through the carpel tunnel below flexor retinaculum to hypothenar muscles. T1-weighted (T1W) and T2 weighted (T2W) images showed multiple linear and tubular hypointense lesions representing thickened medial nerve fascicles with interspersed hyperintense signals representing fat which was homogeneously suppressed on fat saturation images [Figure - 2a], [Figure - 2b], [Figure - 2c]. Diagnosis of neurofibrolipoma of the median nerve was considered based on the classic imaging features. The patient was later operated and decompressive surgery was done. Intraoperative findings showed fatty tissue interspersed with nerve fascicles. Postoperatively, patient showed significant clinical improvement. She started using her left hand for daily routine and the pain was reduced.

Neurofibrolipoma is a rare benign tumor, most frequently occurs in the median nerve, and was first reported in 1953.The other names for neurofibrolipoma include neural fibrolipoma, lipofibromatous hamartoma, perineural lipoma, intraneural lipoma, and lipomatosis of nerve. ^[1],[2] Histopathologically, these lesionsshowfibrolipomatous proliferation which encases and separates the nerve bundles and track along the branching patterns of the involved nerve. Neurofibrolipoma are believed to develop by abnormal proliferation, and development of fibroadipose tissue of nerve sheath ^[2] and the epineurium and perineurium of nerve is also known to be invaded by the fibrofatty tissue. ^[3] Macrodactyly may be the presentation in 66% of neurofibrolipoma cases. ^[4]

On MRI, these lesions show lowintensity linear structures interposed in between high-intensity structures (on T1W and T2W) which get suppressed on fat suppression sequence. They appear as "coaxial cable like" pattern on axial images and "spaghetti string" pattern on coronal images, as seen in our patient. This imaging pattern is considered pathognomonic for the diagnosis of neurofibrolipoma. ^[5] We were able to demonstrate similar imaging pattern on ultrasonography showing echogenic lesion with hypoechoic linear areas of nerve fascicles within.

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