Abstract
Tumor-to-tumor metastasis in the same bone is an extremely rare condition. Limited number of case reports exists for coincidence of benign and malign neoplasms but none for malignant to malignant metastasis. Occurrence of several individual malignancies in the same patient may eventually cause such coexistences. We report an Ollier's disease patient with malignant transformation to chondrosarcoma complicated by a pathologic fracture and eventually whose pathological examination revealed that the lesion was not only the chondrosarcoma but an accompanying metastasis from existing lung adenocarcinoma. This report includes clinical, radiological, histological diagnostic challenges in an unexpected lesion and a review of literature.