Multiple osteocartilaginous exostoses of the lower extremity: A case report

• There is potential for malignant transformation into chondrosarcoma in individuals with MHE, and thus lifelong monitoring will be necessary.
• If an osteochrondroma becomes larger, or increasingly painful surgical intervention should be considered for these patients.
• Multiple osteochondromatois is often an incidental finding and is usually not on the list of differential diagnoses.
• MHE is inherited in an autosomal dominant pattern through a defect in the EXT gene loci.
• An osteochrondroma at the 1st MTPJ contributed to increased bunion pain due to mechanical irritation of the shoegear against the exostosis.

An osteochrondoma is a benign osseous tumor capped by cartilage. Osteochondromas occurring at the distal tibia and fibula are uncommon and even more so when occurring at the first metatarsal head. Osteochondromas usually occur at the metaphysis of long bones; however, they can occur at other cortical bone metaphyses. This is a case report of a 54-year-old male with incidental radiographic findings of multiple osteochondromas around his ankles as well as a solitary osteochondromatous lesion growing proximally off the left first metatarsal head. The multiple osteochrondomas were evident on multiple views, and subsequent histological analysis of the solitary osteochondromatous lesion via total surgical excision confirmed a diagnosis of multiple hereditary osteochrondromatosis.