Deep penetrating benign fibrous histiocytoma of the foot associated with throbbing pain.

Compared to cutaneous benign fibrous histiocytoma (BFH), deep-seated BFH is very rare and poorly recognized. Both cutaneous and deep-seated BFH are usually asymptomatic. We herein report a 25 year-old woman who presented with a painful mass in her foot that was poorly controlled by analgesics and associated with walking difficulty. After preoperative ultrasonographic evaluation, the mass was completely excised and histologic exam showed spindle cells loosely arranged in storiform architecture, with CD34(-), desmin(-), S-100(-), focal CD68(+), vimentin(+), smooth muscle actin(+), and factor XIIIa(+). The patient was diagnosed with deep-seated BFH based on the histologic, radiologic and intraoperative findings.