Thoracoschisis with limb agenesis.

A rare case of thoracoschisis, diaphragmatic and supraumbilical abdominal wall defect with right upper limb agenesis in a neonate is reported.

INTRODUCTION

Thoracoschisis is a very rare congenital anomaly characterized by the evisceration of organs through a defect in the thoracic cage. It may be associated with limb and abdominal wall defects, forming part of the limb body wall complex (LBWC).[1-3] Early vascular disruption, amnion rupture and intrinsic embryonic maldevelopment have been cited as the probable factors related to the pathogenesis of this complex anomaly.

CASE REPORT

A preterm female baby weighing 2.3 kg was delivered by cesarean section at 34 weeks of gestation. An antenatal ultrasonography was done elsewhere during the third trimester, and was reported as gastroschisis in the fetus. The baby presented at birth with evisceration of the liver and intestine through a defect in the right thoracic and supraumbilical part of the abdominal wall on the right side [Figure 1].

Figure 1

Appearance of the case immediately after delivery

The baby died immediately following delivery. An autopsy showed agenesis of the right upper limb with a rudimentary finger-like structure attached to the right shoulder [Figure 2]. The abdominal wall was deficient in the right upper quadrant. There was a large defect in the right thoracic cage with absence of the ribs.

Figure 2

Rudimentary finger-like structure and absence of the right upper limb

The eviscerated abdominal organs were enclosed in a thin and transparent sac, presumably similar to a diaphragmatic hernia sac. Opening of the sac revealed the liver, spleen and almost the entire small and large intestine protruding through the chest wall defect. The right dome of the diaphragm could not be identified and the chest wall defect was found to be extending to the right upper abdomen. The umbilical vessels were attached to the lower part of the sac. The right lung was rudimentary, without any lobulation, and was exposed to the outside. The heart was exposed through the defect of the chest wall. The dissection of the heart did not reveal any gross anomaly. The right subclavian artery could not be identified. The left lung was also hypoplastic, but there was a small but well-formed pleural cavity on the left side with intact left dome of diaphragm.

There was no craniofacial anomaly. There was no evidence of meningomyelocele. Both the lower limbs were normal. The anal opening was normal and was stained with meconium. The external genitalia were of normal female type.

DISCUSSION

The case reported by Davies et al. in 1977 was probably the first report of an association of a congenital defect in the thoracic cage with diaphragmatic defect and limb agenesis.[1] In the case reported by Biri et al.[3] in 2006, there was thoracoschisis, hiatal hernia and extremities agenesis. Thoracoschisis associated with ipsilateral diaphragmatic hernia in a 31-week-old stillborn baby was reported by Derbent et al.[4] in 2001, but it is not known whether there was associated limb agenesis in his case. Davies and Duran[5] studied four cases with ectopia cordis and found an association of sternocostal defect and abdominal wall defect with large omphalocele, but they did mention thoracoschisis as a confused identity. These cases were probably Cantrell's pentalogy, where the chest wall defects were in the midline, unlike our case, and there were no agenesis of the limbs.

The diagnostic criteria for LBWC originally proposed by Van Allen were the presence of any two of the following three malformations: (a) exencephaly/encephalocele and facial clefts, (b) thoraco- and/or abdominoschisis and (c) limb defects. But, it appears that cases presenting with craniofacial and limb defects only without body wall defects may be improperly included in LBWC if one follows these criteria. Other authors have reported extremities agenesis with body wall defects but without craniofacial malformations.[136] In the case reported by Plakkal et al., there was large thoracoabdominoschisis, ectopia cordis with intracardiac defect, absence of subclavian artery and limb agenesis, but no craniofacial anomaly.[6]

It was suggested by Martínez-Frías in 1997 that these cases with LBWC can be classified into two groups: (i) those with isolated body wall defects like gastroschisis and (ii) those with large body wall defects associated with other malformations.[7] Russo et al.[8] described two different phenotypes of LBWC; one with craniofacial defects, called placentocranial adhesion phenotype, and the other without craniofacial defects but with imperforate anus, urogenital abnormalities, lumbosacral meningomyelocele and kyphoscoliosis, called the placentoabdominal adhesion phenotype.

Various theories about the pathogenesis of these defects have been postulated. These include early embryonic maldevelopment, primary rupture of the amnion leading to the formation of amniotic bands, vascular disruption and disturbance of the embryonic folding process.[6]

Antenatal diagnosis is possible with ultrasonography provided the sonologist has prior knowledge about this condition. Termination of pregnancy may be advisable if this anomaly is diagnosed during the early period of gestation. In our case, although antenatal ultrasonography was done, a diagnosis of gastroschisis was made and the parents were advised to continue the pregnancy. The agenesis of one upper limb was not detected by the sonologist and thoracic wall defect was not suspected antenatally.