Case of the Month November 2022 [1] – Fetal skeletal abnormalities

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October 24, 2022

Ultrasound features of different breast cancers ~ Boris Brkljacic (Croatia)

November 2, 2022

Clinical history

A 30-year-old pregnant woman was referred to our department at 16 weeks’ gestation, a routine antenatal ultrasound identified multiple skeletal abnormalities.

Images / Videos

Image 1a-b: Fetal head ultrasound images. Axial (a) and longitudinal (b) scans showing reduced echogenicity of the skull (white arrows) with increased visualization of intra cranial structures and retrognathia (small jaw) (yellow arrow).

Image 2a-b: fetal long bones ultrasound images. Longitudinal scans (a) femur length (b) upper limb showing deformity and marked reduction of long bone length on measurement (red arrows).

Image 3a-b: fetal ultrasound images. (a) Sagittal scan showing a small chest (yellow arrow). (b) Frontal scan showing short and fractured ribs (red arrows).

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Question: Which diagnosis do you consider?

Achondrogenesis
Thanatophoric dysplasia
Osteogenesis imperfecta
Campomelic dysplasia

Correct

CORRECT ANSWER EXPLAINED BELOW

Correct Answer is: Osteogenesis imperfecta

Fetal radiograph AP image.

The triad of bone shortening, decreased bone density and numerous fractures including beaded ribs is consistent with the diagnosis of osteogenesis imperfecta (OI) type II. These findings were confirmed after the medical pregnancy termination by post mortem examination including fetoplacental examination, radiographs (Image 5) and biochemical studies of cultivated fibroblasts from the fetus.

Discussion

OI is a rare inherited bone disease caused by defects in type I collagen synthesis. The most widely used classification for OI distinguishes four types, based on clinical findings and disease severity, type II is the most severe form with perinatal death. It can be diagnosed by ultrasound from 14 weeks of gestation, on specific signs suchas intra-uterine growth retardation or hydramnios. Otherwise, US may show abnormalities of skull, ribs, spine or limbs: decreased echogenicity due to insufficient mineralization, deformities related to fractures, callus formation, increased bone plasticity and micromelia, especially of the femur. however, it is important to recognize that it can be difficult some times to US to distinguish between severe OI and other lethal skeletal dysplasias such as camptomelic dysplasia or thanatotropic dysplasia.

Conclusion

OI type II is a rare lethal pathology of the skeleton with severe abnormalities that may be identified by first trimester ultrasound.

Conflicts of Interest

The author declare no potential conflict of interest.

References

Buisson O , Senat MV, Laurenceau N, Ville Update on prenatal diagnosis of osteogenesis imperfecta type II : an index case report diagnosed by ultrasonography in the first trimester . Case Reports. J Gynecol Obstet Biol Reprod (Paris). 2002 Nov; 31(7): 672-6.
Rauch F, Glorieux FH (2004) Osteogenesis imperfecta Lancet Lond Engl 2004 Apr 24;363 (9418): 1377-85

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