Chilaiditi Sign: When a "Free Air" Scare Turned Out to Be Chilaiditi's Curious Cameo

Chilaiditi sign, a rare radiological finding of colonic interposition between the liver and diaphragm, can mimic pneumoperitoneum and lead to diagnostic confusion. We present the case of an elderly male who was initially treated for a transient ischemic attack and heart failure, discharged in stable condition, and later recalled due to a delayed radiology report suggesting free air under the diaphragm. An urgent CT scan excluded gastrointestinal perforation and confirmed the presence of the Chilaiditi sign. The scan also revealed an incidental mass in the mesentery that was later identified through further investigations as a neuroendocrine tumor, which turned out to be the underlying cause of the Chilaiditi configuration.