The correct answer is B: Chondrosarcoma
Comment: Chondrosarcoma is a relatively rare malignancy, but occurs in about 1% of 20- to 50-year-old patients with multiple hereditary exostoses (MHE). It is generally inherited as an autosomal dominant, although spontaneous mutations can occur. Mutations have been found on chromosomes 8, 11, and 19. A recent study of 173 patients found that 83% had mutations in the EXT1 and EXT2 gene. Mutations in p53, RAS, and EXT3 have also been implicated. The exostoses in MHE can occur on any bone but are usually found in the long bones. These bony protrusions are benign and can vary in size and shape. Depending upon their location, growing children often have considerable pain and can, if not treated, develop shortened bowed legs and arms. Other genetic diseases with a tendency to develop chondrosarcomas are Maffucci syndrome and Wilms' tumor. Click here for the comparative pathology.
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Porter DE, et al. Severity of disease and risk of malignant changes in Hereditary Multiple Exostoses. A genotype-phenotype Study. J Bone Joint Surg Br. 2004;86:1041–1046.
Sandber AA, Bridge JA. Genetics of chondrosarcoma and related tumor. Jour Opin Oncol. 2004;16:342–354.
Terek, RM. Recent advances in the basic science of chondrosarcoma. Orthop Clin North Am. 2006;37:9–14.