A Rare Cause of Pseudoarthrosis: Costal Exocytosis on Facing Surfaces of Each Other.

Osteochondromas are common asymptomatic lesions. The development of chondroid malignancies from cartilage caps has rarely been described. Costal osteochondromas are relatively rare lesions. The incidence of osteochondromas in flat bones is approximately less than 5% of all osteochondromas. Osteochondroma originating from two adjacent ribs and forming a joint with each other is a phenomenon described for the first time in the literature. [ABSTRACT FROM AUTHOR]