Superficial Acral Fibromyxoma, Appearing as Retronychia: A Rare Clinical Entity.

We report a case of a subungual superficial acral fibromyxoma (SAFM) in a 37-year-old male patient who presented with a persistent chronic proximal paronychia of the big toenail of the right leg. Our clinical diagnosis was retronychia, an often misinterpreted condition, which must be suspected in cases of persistent paronychia, especially in the setting of trauma. The nail plate avulsion revealed a subungual tumor, which was surgically excised. Histopathology in combination with immunohistochemistry revealed features suggestive of SAFM. The follow-up examination of the patient showed no recurrence 9 months after the surgery.