Asymptomatic left isomerism with preduodenal portal vein: computed tomography appearance.

Left isomerism (polysplenia), one of the two major variants of heterotaxia with right isomerism (asplenia), may be rarely diagnosed in adulthood. Most cases are nevertheless asymptomatic and incidentally detected during imaging or surgery performed for unrelated conditions. We hereby report a case of left isomerism fortuitously diagnosed in a 55-year-old man with unrelated tachy-cardiomyopathy. Thoraco-abdominal computed tomography revealed a typical preduodenal portal vein (PDPV) associated with a large series of other occult anatomic variations comprising: polysplenia, agenesis of both pancreatic body and tail, complete non-rotation of the bowel and finally azygous continuation of the inferior vena cava. Subtle but highly specific thoracic features of left isomerism were also found with a bilobed right lung and bilateral long hyparterial main bronchi. The features of adult left isomerism are remembered with special attention to the PDPV.