Solitary Subungual Myxoid Neurofibroma of the Thumb: A Case Report

ABSTRACT

PURPOSE: Subungual tumors are a common cause of nail plate deformity, and may be caused by fibrokeratoma, Koene's tumor and glomus tumors. Neurofibromas, either as part of neurofibromatosis or as a solitary tumor are exceptionally rare in the digits. METHODS: A 44-year-old man presented with painless onychodystrophy and nail plate elevation of the right thumb due to a small subungual mass that had started growing 3 years ago. Sensory evaluation of the distal phalanx was normal, and no discoloration nor infection signs were seen. The nail plate was extracted under local anesthesia, and the mass was delicately removed without injury to the nail bed. The nail matrix was repaired with primary closure. RESULTS: Histopathology shows a well circumscribed, cellular tumor with myxoid stroma. Tumor cells were S-100 protein positive, and the patient was diagnosed with myxoid neurofibroma. There has been no sign of recurrence to date, 14 months after the operation. CONCLUSION: Presentation of cutaneous neurofibromas in the digits is an uncommon finding. They may occur as a manifestation of neurofibromatosis or as a solitary tumor. Subungual neurofibromas are exceptionally rare. To our knowledge, there are only ten reports of solitary subungual neurofibroma unrelated to neurofibromatosis to date. We report a rare case of solitary subungual myxoid neurofibroma of the thumb, that was treated through total excision, with preservation of the nail matrix.