Intracytoplasmic inclusion bodies in the chondrocytes of type I lethal achondrogenesis.

Lethal achondrogenesis in the past has been frequently confused with achondroplasia. Clinical and radiologic advances in the last decade have led to clear differentiation of this condition from other types of bone dysplasia. It is further separated into two types on the basis of radiographic and pathologic findings. Re-evaluation of the histologic features has led to the recognition of heretofore unrecognized intracytoplasmic inclusion bodies in the chondrocytes of type 1 achondrogenesis. The finding of inclusions strengthens the differentiation of the two types and may have implications for the pathogenesis of the form of chondrodystrophy.