Cytological Findings and Diagnostic Pitfalls of a Rare Tumor Arising From a Rare Site: "The Story of Chondromyxoid Fibroma of Great Toe".

Chondromyxoid fibroma (CMF) is a rare, benign cartilaginous tumor composed of myxoid and fibrous components, accounting for approximately 1% of all bone tumors. It typically arises in the metaphysis of long bones, with epiphyseal involvement of the short tubular bones of the hand and foot being uncommon. We report the case of a 14-year-old girl who presented with pain and a gradually progressive swelling of the left great toe, occurring after a fracture sustained 2.5 years earlier. Radiological findings were suggestive of an aneurysmal bone cyst or giant cell tumor. Fine-needle aspiration cytology (FNAC) revealed hypercellular smears comprising pleomorphic oval to spindle-shaped cells along with dense, pink osteochondroid material; the cytological diagnosis was rendered equivocal, and malignancy could not be excluded. Subsequent histopathological examination showed a well-circumscribed tumor with a lobular architecture composed of alternating hypocellular and hypercellular areas of myxomatous stroma and immature cartilaginous cells, confirming a diagnosis of chondromyxoid fibroma. Although a low-grade tumor, CMF may show nuclear atypia histologically and can mimic chondrosarcoma; distinguishing between the two is of paramount importance to avoid over-diagnosis and unnecessarily aggressive treatment of this benign entity. Complete surgical resection with long-term follow-up remains the mainstay of management, given the relatively high rate of recurrence.