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Year : 2009  |  Volume : 57  |  Issue : 3  |  Page : 361--362

Fibrolipomatous hamartoma of the median nerve presenting with carpal tunnel syndrome

Radha Sarawagi1, GA Anderson2, Rekha S Cherian1,  
1 Department of Radiodiagnosis, Christian Medical College, Vellore, India
2 Dr Paul Brand Centre for Hand Surgery and Leprosy Reconstructive Surgery (Inclusive of Peripheral Nerve Surgery), Christian Medical College, Vellore, India

Correspondence Address:
Radha Sarawagi
Department of Radiodiagnosis, Christian Medical College, Vellore - 632 004, Tamil Nadu
India




How to cite this article:
Sarawagi R, Anderson G A, Cherian RS. Fibrolipomatous hamartoma of the median nerve presenting with carpal tunnel syndrome.Neurol India 2009;57:361-362


How to cite this URL:
Sarawagi R, Anderson G A, Cherian RS. Fibrolipomatous hamartoma of the median nerve presenting with carpal tunnel syndrome. Neurol India [serial online] 2009 [cited 2020 Apr 9 ];57:361-362
Available from: http://www.neurologyindia.com/text.asp?2009/57/3/361/53264


Full Text

A 37-year-old gentleman presented with weakness, burning sensation, pain and a progressively increasing swelling in the volar aspect of the right palm and wrist for three years. On examination there was wasting of the thenar eminence with muscle power of MRC Grade II and decreased sensation in the median nerve distribution of the right hand. Nerve conduction study showed no response to stimulation of the right median motor and sensory components. Palmar conduction showed no response to stimulation in right median nerve. Magnetic resonance imaging (MRI) of the wrist and hand showed enlargement of the median nerve with hypointense linear serpentine fibers interspersed between hyperintense signal both in T1W, proton density and T2W [not shown in figure] images suggestive of fatty infiltration, giving the appearance of "coaxial- cable- fibers" in the axial plane [Figure 1] and a "spaghetti pattern" in the coronal plane [Figure 2]. The mass caused displacement of the flexor tendons and bulging of the flexor retinaculum. Nerve thickening was extending proximally within the forearm and distally involving the digital branches [Figure 3]. A diagnosis of fibrolipomatous hamartoma of the median nerve causing carpal tunnel syndrome was made.

Under regional block anesthesia and tourniquet control, the patient underwent carpal tunnel release by the open extensile approach with the incision placed ulnar to the axis of the flexed ring finger starting proximal to the Kaplan line to cross the wrist crease at 45 angle to as far as 5 cm in the distal forearm. The tensely stretched transverse carpal ligament and the investing fascial layer of the distal forearm were released longitudinally decompressing the nerve. Internal neurolysis and epineurotomy of the thickened median nerve fascicles was carried out under loupe magnification. The wound healed normally in the postoperative period, with absence of pain and burning sensation. Biopsy of limited nerve section was consistent with fibrolipomatous changes of the median nerve showing expansion of the epinueurium by mature adipose tissue intercepted focally by bands of fibrous tissue separating the fascicle. There was concentric perineurial fibrosis with infiltration of very occasional adipocytes into the perineurium. The endoneurium showed marked loss of myelinated fibers with formation of onion bulbs. On immunohistochemistry the cells forming onion bulbs were positive for S100 protein and negative for epithelial membrane antigen. There was no clinical evidence of improvement in muscle power at the sixth month follow-up although the patient remained symptom-free.

Fibrolipomatous hamartoma of a nerve is a rare soft tissue tumor, which occurs due to fibro-fatty proliferation within the nerve bundles with massive epineural and perineural fibrosis leading to fusiform enlargement of the nerve. [1] It affects most commonly the median nerve and its branches. Other peripheral nerve involvement like ulnar, radial, plantar, peroneal and sciatic has been described. Most cases occur before the age of 30 years. [2] Clinical symptoms consist of gradually increasing swelling, sometimes associated with symptoms of a compression neuropathy. The lesion is also seen to be associated with macrodactyly and macrodystrophia lipomatosa, particularly of a lower extremity. [3] The MR appearance of this condition is unique and characteristic. Thickened nerve fascicles embedded in evenly distributed fat appear as serpentine low-intensity structures surrounded by high-intensity signal in both T1W and T2W images giving the coaxial-cable-like appearance in the axial plane and a spaghetti-like appearance in the coronal planes. This appearance is considered to be pathognomonic of the lesion and routine biopsy is even considered not necessary. [2] Management is usually conservative. But where the patient is symptomatic indicating a severe compression element, decompression surgery as of the carpal tunnel in this patient with median nerve involvement has been shown to provide adequate relief of symptoms. [4]

References

1Silverman TA, Enzinger FM. Fibrolipomatous hamartoma of nerve: A clinicopathologic analysis of 26 cases. Am J Surg Pathol 1985;9:7-14.
2Marom EM, Helms CA. Fibrolipomatous hamartoma: pathognomonic on MR imaging. Skeletal Radiol 1999;28:260-4.
3Brodwater BK, Major NM, Goldner RD, Layfield LJ. Macrodystrophia lipomatosa with associated fibrolipomatous hamartoma of the median nerve. Pediatr Surg Int 2000;16:216-8.
4Bains R, Kotwal A, Saeed W. Recurrent carpal tunnel syndrome in a child due to fibrolipomatous hamartoma of the median nerve successfully treated by limited excision and decompression. J Plast Reconstr Aesthet Surg 2006;59:1394-7.