Calcifying aponeurotic fibroma around posterior tibialis tendon in an elderly patient with flatfoot: A case report

RATIONALE: Calcifying aponeurotic fibroma (CAF) is a rare benign fibroblastic tumor that is commonly in the hand or foot of children or adolescents. PATIENT CONCERNS: A 74-year-old female presented with a progressive pain on the medial foot for 3 years ago. The pain aggravated while walking or in a standing position for more than 20 minutes. She also complained of skin contact along the medial aspect of the foot while trying to wear a shoe. DIAGNOSIS: Physical examination revealed a firm, immobile, nontender mass accompanied with flexible flatfoot. On the single heel raise test, loss of the balance and intensification of the pain were observed. Faintly calcified soft tissue mass is shown in plain radiographs without bone involvement. Magnetic resonance imaging revealed a subcutaneous mass with ill-defined circumscribed subcutaneous mass adherent to the thickened PTT. INTERVENTIONS: The patient underwent a complete excisional biopsy, followed by medial displacement calcaneal osteotomy. OUTCOMES: The excised mass was diagnosed to be CAF on the histologic examination. At the 1-year follow-up, patient remained asymptomatic with no evidence of recurrence and all the radiographic parameters demonstrating flat foot improved. LESSONS: This is the first case of CAF located at PTT presenting with both foot pain and functional disability. In this case, complete excision of the causative structure along with alignment correction can contribute to successful postoperative outcome.