[Lethal osteochondrodysplasias: prenatal and postnatal differential diagnosis].

PURPOSE: Lethal osteochondrodysplasias show an abnormal maturation and a disturbed growth of cartilage and bones. They represent a heterogeneous group of rare genetic diseases. Their incidence is 1 to 3 in 10,000 births.

MATERIAL AND METHODS: We report altogether 5 cases: two of thanatophoric dysplasia, one of achondrogenesis type II and two cases of the rare fibrochondrogenesis. The differential diagnosis in respect to ultrasonographic, morphologic, radiographic and histopathologic criteria of the most common of these diseases are discussed together with a review of the literature.

RESULTS: On the basis of the ultrasound finding of the short-rib-syndrome, it is possible to differentiate between viable and lethal osteochondrodysplasias at 19 to 22 weeks of gestation. The short-rin-syndrome leads to pulmonary hypoplasia.

CONCLUSIONS: It is essential to obtain an exact diagnosis postnatally by radiographic and histopathological examinations to counsel the parents concerning the risk of recurrency. The risk in this heterogeneous group of genetic diseases ranges between less than 1% up to 50% depending on the final diagnosis. Our two cases of fibrochondrogenesis in a consanguineous couple strongly suggest an autosomal recessive inheritance in this disease.