Infected adrenal pseudocyst mimicking a duodenal duplication cyst

A nine year-old boy with a complex medical history, including Phelan-McDermid syndrome, autism spectrum disorder, and focal epilepsy was admitted from Infectious Disease (ID) clinic for persistent fever for over three weeks. Laboratory studies were significant for leukocytosis, elevated inflammatory markers, transaminitis, and anemia. He was initially thought to have an infected duodenal duplication cyst with secondary parapneumonic involvement on imaging. Exploration revealed a densely inflamed suprarenal cyst with a communication to the duodenum. Pathology revealed an infected and hemorrhagic adrenal pseudocyst. We speculate that he had a relatively old or subacute hemorrhagic adrenal pseudocyst that subsequently became infected and perforated into the duodenum and sub-diaphragmatic space. •Infected adrenal pseudocysts is rare, especially amongst older children.•Consider this in patients with persistent fevers and abdominal/flank pain.•Imaging may show peri-adrenal mass with fluid collection and inflammatory changes.•Ultimately, surgical excision is both diagnostic and curative.