Morphologic observations in a case of lethal variant (type I) metatropic dysplasia with atypical features: Morphology of lethal metatropic dysplasia

Metatropic dysplasia accounts for approximately 5% of cases recorded by the International Skeletal Dysplasia Registry, with a single recorded lethal case. Four forms of the disease are currently recognized: type I, lethal autosomal recessive form; type II, nonlethal autosomal recessive form with survival to childhood; type III, autosomal dominant form with typical features, and type IV, a mild form with uncertain inheritance. The literature contains few well-documented reports of the histopathologic findings in metatropic dysplasia. In this report, we present the radiologic and histopathologic features in a case of type I metatropic dysplasia, with the unusual features of a persistent tail, unique lung dysmorphology, and thyroidal agenesis.