Dyssegmental dysplasia with bone entrapment and visceral ramifications.

A stillborn neonate had the typical clinical and radiologic manifestations of dyssegmental dysplasia, an autosomal recessive genetic disorder. The diagnosis was supported by histologic demonstration of the characteristic ballooned chondrocytes in the growth plate and spaces filled with mucoid material in the resting cartilage. Autopsy revealed entrapment of the femoral heads by bone overgrowth in the acetabulum. This notable feature, which has apparently not previously been documented, explained the articular rigidity, which is a significant clinical manifestation. Horizontal grooves on the anterior surface of the spleen were another unusual finding. Our observations further emphasize the importance of comprehensive autopsy in the determination of the pathogenesis of the clinical features and the range of phenotypic expression of an underlying mutation in an unusual genetic disorder.