Chondromyxoid Fibroma of a Rib

Chondromyxoid fibroma (CMF) is an uncommon bone tumor, accounting for <1% of all bone tumors. It generally affects the metaphysis of the long bone of the lower limb and seldom involves the small bones, but the involvement of the flat bones, like ribs, is infrequent.

A teenage girl complained of pain on the right side of the chest for the past 6 months, dull aching, and persistent without any diurnal variation. The chest X-ray examination showed a nodular, hyperdense lesion on the lateral chest wall near the 5-7th rib on the right side. A computed tomography scan confirmed the lesion from the sixth rib with ground-glass matrix and cortical thinning with a smooth margin, without any soft-tissue involvement. An enblock excision of the lesion was done. Histopathological studies showed a well-circumscribed tumor with reactive bone formation at the periphery with lobules of chondromyxoid tissue separated by spindle cells and stellate-shaped cells suggestive of CMF. At 1-year follow-up, she is asymptomatic without any recurrence.

CMFs are rare benign tumors that require histopathological study to differentiate from other benign lesions of the bone. In flat tubular bones like the ribs, enblock resection is the mainstay of treatment.