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2004-07-16-16 Answer to the case of the week # 125 © Cuillier www.TheFetus.net


Answer to case of the week # 125

August 13-27, 2004

Fabrice Cuillier, MD, Cartault F. MD,  Lemaire P. MD,  Alessandri J. MD.

Department of Gynecology, Félix Guyon Hospital, 97400 Saint-Denis, Réunion Island, France.

Ultrasound scan performed in a 25-year-old mother. They had an elder son who was short statured. These are the scans obtained at 23 weeks of gestation.

 

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Routine ultrasound revealed short limbs of the fetus without polyhydramnios. All the long bones were less than the fifth percentile but were normally shaped. The hands and feet were disproportionately long. There was no ulnar deviation of hands and no polydactyly. Ossification appeared normal and no fractures were evident. Normal range of movements was observed. The chest was of normal appearance but the thorax was relatively short and slightly narrow (the thoracic circumference seems just beneath the normal range). The head circumference and biparietal diameter were normal and no frontal bossing was discernible. No other anomaly was found on ultrasound in this female fetus, except the appearance of exophthalmia . Malformations of other organ systems were excluded. The placenta, the umbilical cord and the amount of amniotic fluid were normal. The diagnosis of a skeletal dysplasia was made.The absence of polyhydramnios was judged as a good prognostic sign indicating a high likelihood of the absence of a lethal neonatal chondrodysplasia.

 

Near normal thoracic measurements allowed the exclusion of thanatophoric dysplasia, achondrogenesis, short-rib-polydactyly syndromes and metatropic dwarfism.

Similarly, campomelic dysplasia and osteogenesis imperfecta were considered unlikely due to the relatively straight tubular bones.

Metatropic dwarfism was eliminated because a dumb-bell appearance of the metaphyses of the long bones was not seen [although the current scan showed facial features similar to that seen in metatropic dwarfism].

Since the head circumference of the fetus was normal, the other differentials that were considered and ruled out were mesomelic dysplasia, chondrodysplasia punctata and achondroplasia, the latter for its frequency than for the typical ultrasound measurements.

 

So a probable diagnosis of a non lethal form of dwarfism was suggested and certainly a recurrent  Kniest syndrome .

 

The baby was delivered in good condition by a caesarean section.(P = 2.8 Kg and Apgar scores were 9 at 1 min and 10 at 5 min). Her occipito-frontal circumference was on the fifth percentile and her length [45cm] was below the third percentile. The baby was noted to have a mildly dysmorphic face.The limbs were short with normal hands and feet. There was normal flexion of the fingers and toes and normal range of movements in the joints. Systemic examination showed no other abnormalities and no hepatosplenomegaly. Routine cardiological assessment showed normal structure. X-rays of the long bones showed symmetrical short tubular bones with normal metaphyses, no dislocation of the digits and no other dysplastic features. There was no malformation of the spine or platyspondylia. At six weeks of life, the weight of the baby is 3.8 kg and length is 49 cm

 

The postnatal appearance of the neonate with Kniest syndrome  denotes the peculiar rounded face that is depressed in the midpart, hypertelorism, antimongoloid position of the eyes, large low set ears and small mouth. The characteristic short long bones and the normal toes are also seen.     

 

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