Mixed lymphocytic and collagenous inflammation of the entire gastrointestinal tract under therapy with serotonin and norepinephrine reuptake inhibitors

Drug-induced injury to the gastrointestinal tract has gained growing significance in recent years, and the list of causative medications keeps expanding. Herein, we present the case of a 45-year-old female with major depressive disorder treated with two serotonin and norepinephrine reuptake inhibitors (venlafaxine and duloxetine). She developed nausea and weight loss. Endoscopic evaluation of the upper and lower gastrointestinal tract rendered grossly normal mucosa in all segments. Histological examination, however, revealed lymphocytic esophagitis, collagenous gastritis, celiac disease-like intraepithelial lymphocytosis of the duodenum, and incomplete collagenous colitis. Gastrointestinal side effects of psychoactive drugs are largely underrecognized. This is the first report of a mixed lymphocytic and collagenous pattern of injury affecting esophagus, stomach, duodenum, and colon triggered by combined treatment with venlafaxine and duloxetine. In patients with unclear symptoms, obtaining biopsies from mucosa that is normal upon endoscopic inspection may render decisive clues for clinical management.