Case of fibrolipomatous hamartoma of the digital nerve without macrodactyly.

Fibrolipomatous hamartoma of nerves without macrodactyly is a rare lesion characterized by fibrofatty proliferation causing epineural and perineural fibrosis with fatty infiltration around the nerve bundles. We report an unusual case of fibromatous hamartoma of the ulnar digital nerve of the thumb in a 43-year-old woman. Magnetic resonance imaging revealed a large fusiform mass along the nerve. The findings were unusual and pathognomonic and included a coaxial cable-like appearance on axial sections and a spaghettilike appearance on coronal sections on both T1- and T2-weighted images; these findings were useful for the diagnosis and preoperative evaluation of this lesion. Surgical exploration revealed a yellow, cordlike mass of the digital nerve enlarged by fat. Gross excision could not be done without extensive damage to the nerve. Therefore, a limited excision with biopsy of the fibrolipomatous tissue around the nerve bundles was performed. The histological appearance was consistent with fibrolipomatous hamartoma. There was no recurrence of the mass and no neurological deficit 3 years after surgery. Some authors have suggested that invasive excision can cause catastrophic sensory or motor deficits because of the extensive fatty infiltration of the nerve fascicles. In conclusion, the recommended treatment for this lesion is limited excision with only biopsy to confirm the diagnosis.