Periosteal chondroma of the rib: A case report

BACKGROUND: Periosteal chondroma is a very rare benign tumor that develops adjacent to the cortical surface of bone and beneath the periosteal membrane. Periosteal chondroma of the rib is an extremely rare entity. CASE SUMMARY: The patient was a 43-year-old man who had been incidentally found to have a mediastinal mass 1 mo earlier. Plain computed tomography showed a lobulated soft tissue mass on the right side of the T4/5 vertebra that measured about 47 mm × 28 mm in the transverse view and contained diffuse stippled calcification. The mass caused cortical scalloping of the right fourth rib and marginal bone sclerosis. Enhanced computed tomography showed mild enhancement of the mass. Magnetic resonance imaging showed a lobulated mass on the right side of the thoracic vertebra with long TI and T2 signals, mottling, and patchy long T1 and short T2 signals inside. The lesion had a hypointense rim. Enhanced magnetic resonance imaging showed enhancement predominantly at the periphery of the tumor. The tumor was approached through a right posterolateral thoracotomy, and parts of the fourth and fifth ribs were excised with the tumor. Postoperative pathological analysis revealed periosteal chondroma of the rib. CONCLUSION: Periosteal chondroma of the rib has a low incidence and typical imaging manifestations. Understanding its imaging features is helpful to ensure a correct preoperative diagnosis.