A 7 yo girl with hereditary multiple exostosis presents with a growing painful mass on her right femur. The following is an H&E stained slide of the mass.
The diagnosis is most likely:
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Answer: b, Chondrosarcoma.
Chondrosarcoma is a relatively rare malignancy, but occurs in about 1% of 20-50 yo 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.
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. 86. 1041-6. (2004)
Sandber, AA and Bridge, JA “Genetics of chondrosarcoma and related tumor”. Jour Opin Oncol 16:342-54 (2004).
Terek, RM “Recent advances in the basic science of chondrosarcoma”. Orthop Clin North Am 37:9-14 (2006)
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