Case of the Week #575

Ivanov Ivan; Teregulova Liliana
Center of prenatal ultrasonographic diagnosis. Kazan, Russia

Posting Dates: Jan 31, 2023 - Feb 14, 2023

Case Report: A 20-year-old primigravida was sent to our genetic center with a diagnosis of bilateral clubfoot. The first-trimester screening was reported to be normal. The ultrasound scan at 23 weeks revealed the following findings.

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Answer

We present a case of Larsen syndrome. Postmortem images of the fetus confirmed congenital genu recurvatum with pathological hyperextension of the knee (Image 1, 2).

Our ultrasonographic examination revealed following findings:

Image 1, Video 1: Abnormal facial profile with slightly flattened bridge of the nose
Image 2, Video 2: Congenital genu recurvatum with pathological hyperextension of the knee

Discussion

Larsen syndrome is a congenital disorder discovered in 1950 by Larsen and associates when they observed dislocation of the large joints and facial anomalies in six patients. Larsen syndrome is a rare congenital anomaly with estimated incidence of approximately 1 in 100,000 births [1].

Patients with Larsen syndrome normally present with a variety of symptoms, including congenital anterior dislocation of the knees, dislocation of the hips and elbows, flattened facial appearance, prominent forehead, and a depressed nasal bridge [2]. The major clinical presentation can be non-specific, thus some authors have suggested the syndrome may represent a collection of similar phenotypes with underlying defects [3].

Congenital genu recurvatum, defined as a pathological hyperextension of the knee greater than 30° and limited flexion, is associated with Larsen syndrome with high clinical variability [4].

References

[1] Larsen L, Schottstaedt E, Bost F. Multiple congenital dislocations associated with characteristic facial abnormality. J Pediatr 1950; 37: 574-581.
[2] Mitra N, Kannan N, Kumar VS, et al. Larsen Syndrome: A Case Report. Journal of Nepal Paediatric Society. 32.1 (2012): 85-87. Print.
[3] Mostello D, Hoechstetter L, Bendon RW, et al. Prenatal diagnosis of recurrent Larsen syndrome: further definition of d lethal variant. Prenat Diagn 1991;11: 215-225.
[4] Harris R, Cullen CH. Autosomal dominant inheritance in Larsen syndrome. Clin Genet 1971; 2: 87-90.