Unmasking probable spondylocostal dysostosis: A rare cause of infant respiratory distress

INTRODUCTION

Spondylocostal dysostosis (SCDO) is a rare congenital disorder within the Jarcho–Levin spectrum, characterised by multiple vertebral segmentation defects and rib malformations. These thoracic deformities restrict lung expansion and predispose affected infants to recurrent respiratory morbidity and progressive scoliosis.^[1,2] Mutations in genes including DLL3, MESP2, HES7, LFNG, and TBX6 have been implicated, most often in autosomal recessive inheritance, particularly in consanguineous families.^[3,4]

CASE REPORT

A 5-month-old male infant, firstborn, at term (birth weight: 2,550g) to first-degree consanguineous parents with no other significant family history, presented with severe respiratory distress. Antenatal ultrasonography had been unremarkable, and there was no family history of congenital anomalies or teratogen exposure. The neonate had not required intensive care at birth. On admission, he was tachypnoeic with marked respiratory distress. Clinical examination revealed scoliosis, a disproportionately short trunk, a low posterior hairline, narrowing of the thoracic cage, and relatively short lower limbs [Figures 1 and 2].

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Figure 1: Pre-auricular tag in the right ear (Left arrow) and back showing scoliosis (Right arrow).

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Figure 2: Crowding of ribs on the left side and thoracic cage narrowing with short trunk.

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Investigations showed

• Chest radiograph: Right-sided consolidation with vertebral and rib anomalies.

• Echocardiography: Small ventricular septal defect (3 mm).

• Ultrasound abdomen: Mild hepatomegaly.

• Ultrasonography of the cranium: No significant abnormality.

• Magnetic resonance imaging of the brain: No significant abnormality.

The infant was hospitalised for 6 weeks and managed with high-flow nasal cannula oxygen, intravenous antibiotics for pneumonia, chest physiotherapy, and nutritional support. The child was evaluated for abnormality. Skeletal survey showed bilateral asymmetric rib deformities, rib fusions, and segmentation defects of thoracic vertebrae with kyphoscoliosis (computed tomography [CT] chest and chest radiograph) [Figures 3 and 4]. Genetic testing could not be performed due to financial constraints. The family was counselled regarding the prognosis and the need for long-term multidisciplinary care. However, the child was lost for follow-up.

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Figure 3: Skeletal survey: Bilateral asymmetric rib deformities, rib fusions and segmentation defects (white arrow) of thoracic vertebrae with kyphoscoliosis.

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Figure 4: High-resolution computed tomography thorax: Butterfly vertebrae (T1–T3) (white arrow), rib flattening and rib fusions (orange arrow).

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DISCUSSION

This infant displayed the classical phenotype of SCDO: multiple vertebral segmentation anomalies (butterfly vertebrae, scoliosis), rib deformities (fusions, asymmetry, flattening), and a restrictive thoracic malformation, as seen on CT thorax, resulting in early respiratory compromise.^[1,2]

The key differentials include:

• A “crab-like” thoracic cage characterises spondylothoracic dysostosis.^[5]

• Klippel–Feil syndrome is marked by cervical vertebral fusion and a low posterior hairline, with minimal rib involvement.^[6]

• Jeune thoracic dystrophy, presenting with diffuse thoracic narrowing and variable outcome.^[7]

Consanguinity in this case supports an autosomal recessive inheritance pattern. Mutations in DLL3 and MESP2 are well-documented causes of SCDO.^[3,4] Prognosis depends on the severity of thoracic insufficiency. Many affected infants experience recurrent respiratory infections, progressive scoliosis, and impaired growth. Multidisciplinary management is essential, involving pulmonology, orthopaedics, cardiology, and genetics.^[2-4]

CONCLUSION

SCDO should be suspected in infants presenting with unexplained respiratory distress and thoracic malformations, particularly in the setting of consanguinity. Early recognition allows for supportive management, genetic counselling, and timely referral for multidisciplinary care.