Abstract
Autoimmune enteritis (AIE) is a rare inflammatory condition with intractable diarrhea and malnutrition. Most cases are diagnosed during infancy, but rare adult-onset cases can occur. We present a male patient in his 60s with a history of psoriasis and psoriatic arthritis on etanercept who developed refractory and intractable diarrhea and malnutrition. Serologic and infectious work-up was negative. Despite holding etanercept and attempting treatments with antibiotics, diphenoxylate with atropine, loperamide, octreotide, and pancreatic enzymes, his symptoms persisted, ultimately necessitating total parenteral nutrition. Esophagogastroduodenoscopy showed duodenal bulb ulcerations and colonoscopy was normal. Biopsies showed intraepithelial neutrophils within the duodenal mucosa, active lymphocytic cryptitis, crypt abscesses, and villous atrophy and blunting without granulomas consistent with autoimmune enteritis. The patient was started on prednisone, budesonide, and adalimumab with improvement. After 4 months, he was maintained on adalimumab monotherapy, his bowel habits normalized, and he was able to tolerate a normal diet. This case illustrates a rare presentation of autoimmune enteritis in a patient with well-controlled psoriatic arthritis with etanercept.