Mesomelic skeletal dysplasias.

Mesomelic shortening of the extremities lends itself as a useful clinical and/or radiologic sign to characterize a group of hereditary bone dysplasias. Table 1 and Figure 4 are presented to facilitate the comparison between the many different types of mesomelic dwarfism. Differential diagnosis between these types is not difficult because of the specific bone changes and extraskeletal malformations present. As in many hereditary syndromes, however, there may be wide clinical variability within a single entity, and meticulous clinical and radiologic examination must be done to arrive at the correct diagnosis. Certain other forms of chondrodystrophies, such as achondroplasia, hypochondroplasia, pseudoachondroplasia and distrophic dwarfism, can be easily differentiated from the mesomelic dysplasias by their clinical features and skeletal radiographs. Nothing is known about the pathogenesis of the various forms of mesomelic dysplasias. There is no available specific treatment, although corrective surgery has benefited selected patients. The correct diagnosis is, however, important both for prognostication and accurate genetic counseling.