Intestinal Rotation Anomalies

Isolated dextrogastria with eventration of right hemidiaphragm and hiatal hernia in an adult male

BACKGROUND

Type 2 isolated dextrogastria in conjunction with protrusion of the right hemidiaphragm and hiatal hernia is an uncommon anomaly among all transpositions of the viscera. Clear diagnosis is not straightforward in such cases both clinically and with various imaging techniques leaving often only laparotomy for diagnosis.

CASE PRESENTATION

Here, we discuss the case of a so far asymptomatic 19-year-old male, who had a 3-month history of abdominal pain and 2 days of vomiting with absolute constipation, and reduced air entry in the base of the right lung. A large air fluid level was found in the right lower hemithorax, furthermore, a loss of the normal diaphragmatic outline, and paucity of the bowel gases in the rest of the abdomen. Computer tomography with contrast was suggestive of loss of right lung volume, with stomach and bowel loops herniating into the right hemithorax and compressive atelactatic changes in the adjacent lung alongside an enlarged liver. A barium test showed the stomach fundus and body posteriorly positioned, while both duodenal bulb loops and the duodeno-jejunal junction alongside the small and large bowels were detected in their normal positions.

CONCLUSION

In case of visceral transpositions, routine diagnostic blood and radiological tests may lead the health care provider to misdiagnosis. It is necessary, in particular when surgery is required, to carefully elucidate the organ anomaly. The use of additional imaging and radiological methods may be called for; CT scan and a barium test were critical here. This is the first case of isolated dextrogastria with eventration of right hemidiaphragm and hiatal hernia reported from Pakistan providing insights for diagnostic procedures.

Midgut Laterality Is Driven by Hyaluronan on the Right

For many years, biologists have focused on the role of Pitx2, expressed on the left side of developing embryos, in governing organ laterality. Here, we identify a different pathway during left-right asymmetry initiated by the right side of the embryo. Surprisingly, this conserved mechanism is orchestrated by the extracellular glycosaminoglycan, hyaluronan (HA) and is independent of Pitx2 on the left. Whereas HA is normally synthesized bilaterally as a simple polysaccharide, we show that covalent modification of HA by the enzyme Tsg6 on the right triggers distinct cell behavior necessary to drive the conserved midgut rotation and to pattern gut vasculature. HA disruption in chicken and Tsg6-/- mice results in failure to initiate midgut rotation and perturbs vascular development predisposing to midgut volvulus. Our study leads us to revise the current symmetry-breaking paradigm in vertebrates and demonstrates how enzymatic modification of HA matrices can execute the blueprint of organ laterality.