Neural Fibrolipoma of the Ankle: A Case Report and Review of the Literature

Neural fibrolipomas are exceedingly rare benign tumors composed of hypertrophied fibrofatty tissue intermixed with nerve tissues. Our review of the published data identified only 15 cases of this tumor involving the foot and/or ankle region. An otherwise healthy 35-year-old male was referred for evaluation of a painless soft tissue mass present in the anterior left ankle. The mass had been present for approximately 6 to 7 years and had recently increased in size. Physical examination demonstrated a prominent, fluctuant mass present in the left ankle measuring 4 cm in diameter. The mass was not well-defined, was immobile, and did not transilluminate. No gross pedal deformity was present. Radiographic imaging revealed increased soft tissue prominence and density to the anterior ankle without bone involvement. Magnetic resonance imaging demonstrated a mass isointense to fat on all sequences without contrast enhancement, suggestive of a lipoma. Surgical excision was performed; the mass was yellow and lipomatous in nature. The mass was intimately associated with the superficial peroneal nerve, which had to be sacrificed during excision. The pathologic examination of the mass revealed findings consistent with a neural fibrolipoma. The patient healed uneventfully without recurrence. His only complaint was of some residual numbness in the medial foot.