Caudal duplication syndrome.

Caudal duplication syndrome is a rare entity in which structures derived from the embryonic cloaca and notochord are duplicated to various extents. Its prevalence at birth is less than 1 per 100,000. The term caudal duplication encompasses a spectrum of anomalies and is often used to describe incomplete separation of monovular twins or referred to as part of the spectrum of anomalies associated with conjoined twinning. It usually includes multiple rare malformations and duplications of distal organs derived from the hindgut, neural tube, and caudal mesoderm. It was postulated that the disorder is related to misexpression of one or more of the distal HOX genes, potentially HOX10 or HOX11, leading to abnormal proliferation of caudal mesenchyme. The malformations are usually diagnosed by anomaly scan in the second trimester. Here we report the case of a baby presenting on the first day of life with complete duplication of caudal structures below the dorsolumbar level.

INTRODUCTION

Caudal duplication syndrome is a rare anomaly associated with complete/partial duplication of the spine, spinal cord, and of other caudal structures including urogenital and gastrointestinal tract with some degrees of neurological dysfunction. We report the case of a female baby who presented with this defect on the 1st day of her life.

CASE REPORT

A female baby, delivered by cesarean section at term to a second gravida mother was sent to our neonatal intensive care with obvious structural anomalies. Physical examination revealed duplicity of the anal orifice and vulvar introit with the passage of meconium through both anal orifices [Figure 1]. She also had an umbilical hernia. She was subjected to the following imaging modalities: (1) Echocardiography, (2) conventional X-ray, and (3) magnetic resonance imaging (MRI) of pelvis. Echocardiography revealed inter-atrial communication in the form of a patent foramen oval and no other structural defects. X-ray revealed duplication of the vertebral column below the dorso-lumbar junction. MRI revealed the following anomalies [Figures 2 and 3]:

Figure 1

Complete duplication of external genitalia and anal orifice

Figure 2

Magnetic resonance imaging showing vertebral duplication and myelocystocoele

Figure 3

Magnetic resonance imaging PIC 2

Spinal anomalies: Hemivertebra noted at dorsolumbar junction with duplication of vertebral column below that level along with the sacro-coccygeal agenesis. Spinal dysraphism was noted in the lower lumbar region. Terminal myelocystocele with terminal cord syrinx was observed. There was an evidence of tethered cord with dorsal dermal sinus

Duplications of urinary bladder, uterus, and rectum were noted

There was malrotation of right kidney

Enteric duplication cyst was noted in the right iliac fossa

An interesting observation was a hyperintense lesion at first and second thoracic vertebra level giving impression of a sequestered lung segment or a para-esophageal hernia.

The radiological opinion could not exactly delineate the level of duplication of gut.

DISCUSSION

Spinal and spinal cord duplicity span a spectrum of malformations ranging from the simple fibrous bands splitting the cord to complete the duplication of caudal structures. Only when there is associated duplicity of vascular structures and/or organs such as bladder and distal gastrointestinal tract is the term caudal duplication syndrome coined.

The embryologic basis of this syndrome is unclear. Some authors are of the opinion that it results from incomplete division of monozygotic twins. Pang et al.[1] advanced a unified theory for the spinal cord duplication disorders, suggesting that all result from abnormal adherence between ectoderm and endoderm. Dominguez et al.[2] concluded that these anomalies originate from damage to the mass formed by caudal cells and posterior gut at approximately 25 days of the pregnancy. Polytopic primary developmental field defect or a disruption sequence or somatic or germ line mutation in certain developmental genes could be involved. Most patients have associate moderate to severe neurodeficit; although some can be neurologically normal.[3] Our patient had moderate hypertonia of both lower limbs. She is now 2 months old being followed-up at the neonatal surgery and neurodevelopmental clinics pending further plan of action.