Spondylocostal dysostosis associated with right-sided polythelia, right-sided rib deformity and meningocoele: Case report with review of literature.

Spondylocostal dysostosis (SCD) is a rare anomaly of axial skeleton due to flawed embryological development. A newborn baby boy with right-sided polythelia, meningocoele, fan-like configuration of third and fourth rib, fused fifth and sixth rib and third thoracic hemivertebra was delivered to a second gravid mother by elective caesarean section. Baby was active, cried immediately after birth, had normal muscle tone and reflexes. He passed urine and meconium within 24 h of birth. Based on clinical examination and radiological picture, a diagnosis of SCD with meningocele with right-sided polythelia was made. Our case is the first SCD with polythelia and meningocele in newborn. SCD with right-sided polythelia and rib deformity with neural tube defect (NTD) may be due to a genetic defect with the culprit genes missing. Further genetic and embryological studies might find a link between right-sided rib defects, polythelia and NTD.

Introduction

Spondylocostal dysostosis (SCD) is a rare disorder due to genetic mutation resulting in abnormality of axial skeleton and associated rib deformities. There are only two case reports in literature with neural tube defect (NTD) and supernummary nipple.[12] We present a newborn, diagnosed with SCD, polythelia and meningocoele. Association of NTDs has been reported previously with SCD but this case has associated polythelia which has not been reported in newborn.

Case Report

Term baby boy, weighing 3 kg was delivered by emergency cesarean to a second gravid mother - section was done for nonprogression of labor. Mother had history of spontaneous abortion at 3 months of gestational age. Her viral markers including Toxoplasmosis, Rubella, Cytomegalovirus and Herpes profile was negative. Baby cried immediately after birth, but had malformations in the form of right-sided polythelia, [Figure 1] and spina bifida occulta. An extra nipple was located caudal to normal nipple and was more prominent. On palpation, bony defects could be appreciated just below the extra nipple giving rise to a suspicion of defective rib cage. There were no other anomalies like dysmorphic facies, hernias and imperforate anus. Rest of the systemic examination was normal.

Figure 1

Right-sided polythelia

In view of congenital malformations, chest X-ray, X-ray spine, ultrasonography (USG) cranium, USG abdomen, spine was done. X-ray spine anteroposterior and lateral view suggested fan-like configuration of third and fourth rib fused sixth to sixth rib, third thoracic hemivertebra [Figure 2]. Chromosomal analysis of the child was normal.

Figure 2

Infantogram (anteroposterior and lateral view showing fan like configuration of third and fourth rib, fused fifth to sixth rib, third thoracic hemivertebra)

Discussion

SCD is a rare anomaly caused due to faulty embryological development of the axial skeleton during initial stages of gestation. Dominant rib anomaly differentiates it from spondylothoracic dysostosis (STD). Patchy spinal involvement differentiates it from the Jarcho–Levin syndrome (JLS). Autosomal dominant and recessive transmissions are known. SCD association with spina bifida occulta has been shown previously.[3] There are studies which suggest an etiological link between NTD and segmental costovertebral defect.[4] Patients with SCD have typical rib anomalies and vertebral abnormalities such as hemivertebrae and butterfly vertebrae.[5] SCD, STD and JLS all have vertebral involvement, with increasing severity. JLS is the most severe form. Literature review has shown very few cases of SCD with NTD and only two with associated supernummary nipple. Duru et al. reported a 2-year-old girl with polythelia and rib deformity on right side with NTD and bilateral foot deformities, chromosomal analysis was not done in that case.[3] Yilmaz et al. presented 2-year-old female child with thoracolumbar scoliosis, skin lesion, hypertrichosis, double nipples on the right side and skin lesion on the back suggestive of split cord. Investigation further revealed that first four ribs were absent on right side. There was an irregular appearance at the fifth with sixth ribs, chromosomal analysis was normal.[2] Dias and Walker explained about split cord malformations and other related complex dysraphic malformations.[6] According to them the embryogenesis of split cord malformations and related malformations occur due to failure of midline axial integration during gastrulation. At least four gene mutations are known to cause SCD. Mutations in the DLL3 gene cause SCD type 1: mutations in the mesoderm posterior protein2 gene cause SCD type 2; mutations in the LFNG gene cause SCD type 3; and mutations in the HES7 gene cause SCD type 4. The SCD genes play a role in the Notch signaling pathway and disruption of this pathway results in malformation and fusion of the bones of the spine and ribs as seen in SCD. Researchers suggest that additional genes in the Notch signaling pathway might also be involved.[7]

Conclusion

It is vital to comprehensively examine the NTD patient and to rule out associated abnormalities. Early diagnosis of SCD in neonatal period as in this case will help us to take aggressive measures in treating lung infections as defective rib cage will hamper the normal growth of lungs. We must take precautions to prevent direct trauma to heart or lungs in view of deficient rib cage. Our case is the first SCD with polythelia and meningocele in newborn. SCD with right-sided polythelia and rib deformity with NTD may be due to a genetic defect with the culprit genes missing. Further genetic and embryological studies might find a link between right-sided rib defects, polythelia and NTD.

Declaration of patient consent

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Conflicts of interest

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