Correspondence Address:
C S Sheela Devi
367, Adarsha, 6th cross, T K layout, Kuvempunagar, Mysore-570 009, Karnataka
India

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Sir,

The term lipofibromatous hamartoma (LFH) of the nerve is most commonly used to describe the proliferation of mature adipocytes within the peripheral nerves, resulting in a palpable yellow neurogenic mass. LFH is a rare disorder that most commonly manifests in the nerves of the upper extremity. [1] The median nerve is the most commonly involved peripheral nerve. Patients typically present in their third or fourth decade of life, with a long history of painless swelling in the distal forearm that often is first noted in childhood. [1]

A 20-year-old male patient presented with a soft, mobile swelling of two years duration in the palmar aspect of right hand in the region of the thenar eminence and extending to the middle finger. No neurological deficits were elicited. An X-ray of his right hand was done and the radiologist's provisional diagnosis was hemangioma. Per-operatively, a gray-yellow fusiform mass was seen attached to the median nerve, measuring 6x4x3cm. He underwent an excision biopsy of the mass.

Grossly, the specimen consisted of multiple gray-yellow fragments, totally measuring 5x3cm. Histologically, the epineurium of the nerve was expanded by infiltrating mature fibro-fatty tissue [Figure 1] with perineural fibrosis and septation [Figure 2] and [Figure 3]. The nerve fascicles were atrophic. A diagnosis of LFH of the nerve was made. The patient had deficits in hand function following the biopsy. He was advised a nerve graft for the same. However, he was lost to follow-up.

LFH, first described in English literature by Mason in 1953, is a rare condition characterized by diffuse enlargement of the nerve caused by overgrowth and proliferation of fibrofatty tissue. The lesion is described as a hamartoma because fat and fibrous tissues are normal constituents of the connective tissue stroma of a nerve. [2] Although most commonly reported in the median nerve, the lesion also occurs in the radial, sciatic, ulnar, cranial and plantar nerves. [2],[3] More than one-third of the cases are associated with macrodactyly when it is referred to as macrodystrophia lipomatosa. The most frequent presentation of LFH is a swelling or mass on the volar aspect of wrist or distal forearm. Neurologic deterioration occurs after some years. [3]

Magnetic Resonance Imaging (MRI) has a diagnostic role in the investigation of a suspected LFH. [1],[3] A characteristic feature is the appearance of serpentiform nerve fascicles surrounded by fibro fatty tissue within the expanded nerve sheath. On coronal images, the nerve has a spaghetti-like appearance and a coaxial cable-like appearance on axial images is pathognomonic of LFH. [3],[4] MRI should be always supported with a tissue biopsy, particularly in cases presenting as an asymptomatic mass lesion. [3] The biopsy, however, has to be of a small cutaneous nerve. [5]

At surgery, LFH of the nerve appears as a soft gray-yellow, fusiform mass that has diffusely infiltrated and replaced portions of a large nerve and its branches not adherent to surrounding tissues. [5],[6] Microscopic examination reveals the epineurium expanded by adipose tissue. [6] This infiltration causes atrophy of the neural elements often accompanied by extensive perineural fibrosis. [3]

The histologic differential diagnoses include neuroma, neurofibroma, intraneural lipoma and diffuse lipomatosis. However, in LFH, there is atrophy of neural elements, is diffusely infiltrative and it primarily affects the nerves. [5]

Treatment of LFH is difficult because the lesion cannot be completely excised without sacrificing the involved nerve. [2] Inadvertent excision, as in this case, may inevitably lead to a significant neurological deficit. [6] LFH of the nerve is a rare cause of nerve associated swelling. A combination of MRI and biopsy is diagnostic. However, the importance of recognizing its possibility lies in the fact that a poorly planned surgical treatment is a greater hazard than the natural clinical outcome. This underlines the need for a greater awareness of this condition by the trinity of clinician, radiologist and pathologist.

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