Stress and alcohol abuse are risk factors for duodenal ulcer in this case.

The distribution of the collection is explained by the anatomy. The anterior right pararenal space is also the mesocolon, bounded posteriorly by the anterior renal fascia. This sometimes inserts into the posterior wall of the duodenum connecting the posterior duodenum directly to the perirenal space.

The radiodense foreign body was a mystery and we initially thought this could have been a bone fragment. The collection progressively resolved following CT-guided percutaneous drainage and on follow-up CT the foreign material appeared to disintegrate and then disappear. Perhaps it was due to ingested tablets?

Emphysematous pyelonephritis was not considered as a differential diagnosis due to the normal appearance of the right kidney.