Hereditary multiple cartilaginous exostoses is a syndrome characterised by the development of multiple osteochondromas. The diagnosis is typically made around the age of 12 years, and the prevalence is estimated at 1:50,000. During skeletal growth, the osteochondromas are benign, but in adult life malignant transformation into chondrosarcomas can occur.

This study was a literature survey based on a systematic search of the PubMed database for articles with the term "hereditary multiple exostoses chondrosarcoma". The search returned 157 articles, of which 13 had a sufficient level of evidence. These publications were examined thoroughly, focusing on the development of sarcomas, symptoms and the risk of malignant degeneration.

There is no consensus regarding the frequency of malignant transformation of multiple cartilaginous exostoses into sarcomas, which varies from less than 1% to 25%. The most reliable estimation seems to be 1-2%. The survey of the literature shows that no risk groups can be identified. However, exostoses in the axial skeleton are more prone to develop into chondrosarcomas than peripheral exostoses.

It is indisputable that malignant transformation occurs, and we therefore propose that a follow-up programme be launched with clinical examination by magnetic resonance imaging or bone scintigraphy every second year. The purpose of such programme would be to discover the sarcomatous development as early as possible to improve the survival prognosis of the patients. This screening programme should be centralised at tumour departments.