[Rib-originated fibrous dysplasia: report of a case].

The incidence of fibrous dysplasia (FD) is not frequent in the case of benign bone tumors of the chest wall, and differential diagnosis between FD and the malignancy on the basis of imaging findings is difficult. We report a case of a painful FD lesion (size, 9×8 cm) that originated from the 5th rib of a 52-year-old man and was surgically resected. His symptoms improved after the operation. Painful and large FD lesions should be resected because of a difficulty in differential diagnosis from malignant tumors.