This is a case report of a 26-year-old healthy man with chronic diarrhea for 2 years. He was initially believed to have irritable bowel syndrome by his primary care physician after all stool studies yielded negative results. His symptoms persisted, which prompted a referral to a gastroenterology specialist. The patient's esophagogastroduodenoscopy revealed variable villous blunting and a paucity of CD 138 plasma cells, which helped reveal the final diagnosis. This cases illustrates a unique presentation of a common primary immunodeficiency that allergy/immunology specialists, along with primary care specialists, will likely encounter.