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Clinical Problem Solving: Radiology
September 20, 2010

Radiology Quiz Case 2: Diagnosis

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Arch Otolaryngol Head Neck Surg. 2010;136(9):927-928. doi:10.1001/archoto.2010.141-b

Hereditary multiple exostoses, familial osteochondromatosis, and diaphyseal aclasis are synonyms for a rare, autosomal dominant clinical condition that is characterized by multiple osteochondromas. An osteochondroma is a cartilage-capped bony excrescence that typically grows from the metaphysis of long bones. It is the most common type of benign bone tumor, with solitary tumors occurring in 1% to 2% of the population. It is also the most common type of radiation-induced benign bone tumor.1Hereditary multiple exostoses were first described by Hunter2in 1835. The overall prevalence is 1:50 000, with virtually all patients presenting in early childhood.3Recent genetic studies have identified mutations in 2 genes— EXT1and EXT2—that are responsible for more than 70% of the cases of HME.4Most of these cases involve loss-of-function mutations supporting a tumor suppressor function of the EXTgenes. EXT1has been shown to regulate chondrocyte proliferation and differentiation during endochondral bone development, thereby providing a promising genetic basis for this disease.5

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