Chondrosarcoma in Metachondromatosis: A Rare Case Report

Metachondromatosis which was first described in 1971 by Maroteaux is a rare genetic disease consisting of osteochondromas and enchondromas, caused by loss of function of the PTPN11 gene. It is distinct from other cartilaginous tumors such as multiple osteochondromas and hereditary multiple exostosis by the distribution and orientation of lesions, and pattern of inheritance. In Metachondromatosis osteochondromas typically occur in hands, feet, femur, and tibia while enchondromas commonly affect the pelvic bones and femurs. Both tumors are generally reported to regress in adulthood. To the best of our knowledge only one case of Chondrosarcoma has been reported, and our case is the second reported case of Chondrosarcoma in metachondromatosis

Aneurysmal Bone Cyst: An Analysis of 38 Cases and Report of Four Unusual Surface Ones

Aneurysmal bone cyst (ABC) is a benign expansile bone tumor, most commonly involving the medulla of long bones. ABC rarely arises within the cortex or in the subperiosteal region, radiographically mimicking other conditions, in particular surface osteosarcomathat is low-grade in nature and may go secondary ABC changes, and telangiectatic osteosarcoma. Both of these are sometimes mistaken microscopically for primary ABC. We review the characteristics of ABC cases in our center and report four unusualsurface ABCs arising in the subperiosteal or cortical region of long bones, identified among 38 histologically proven ABCs during a four-year period in our center. The surface ABCs occurred at an older agewith a predilection for diaphysis of femur, tibia, and humerus