AbstractObjectiveInflammatory reactions caused by immunosuppression appear a particular interesting disease due to its very specific and partly unclear etiopathogenesis.Based on clinical case-specific management experiences and selective references from the literature, the rare case of an acute intraabdominal inflammation as unusual complication or side effect (at the gastrointestinal [GI] tract) of the ongoing immunosuppressive medication using Mycophenolate mofetil and Tacrolimus after previous liver transplantation is to be illustrated.Case presentationMedical history (hx): 1) Current: A 68-years old male patient underwent abdominal CT scan because of pain in the left lower abdomen with the suspicious diagnosis of diverticulitis leading to initiation of antibiotic therapy 24 h prior to the transferral to the own hospital for adequate liver transplantation (LTx) follow-up investigation. 2) Medication contained Sitagliptin 1 × 100 mg, Omeprazol 1 × 40 mg, Mesalazin 500 mg 3 × 2, Movicol 1 (on demand), Mycophenolate mofetil 2 × 500 mg, Tacrolimus 2 × 1 mg and Hydrochlorothiazid 1 × 2.5 mg. 3) Additional diagnoses included arterial hypertension, diabetes mellitus and urinary bladder diverticle. 4) Previous surgical intervention profile comprises resection of liver segments IV/V due to HCC (2011), orthotopic liver transplantation because of HCC caused by alcohol-induced liver cirrhosis (2013) and an intervertebral disc operation (2018). Physical examination of the abdomen revealed marked tenderness in the lower left quadrant. The abdominal wall was soft and there were no defensive tension and no peritonism. The patient was in good general condition and nutritional status. He was cardiopulmonarily stable and oriented to all qualities. Diagnostic measures showed a CRP of 38.0 (normal range, < 5) mg/L and a white blood cell count within normal range. Leading diagnoses were found using abdominal CT scan, which demonstrated an extended diverticulosis and an appendicitis epiploica within the immediate subperitoneal region of the left lower abdomen with an oval fat isodense structure in the region of the sigmoid colon with surrounding inflammatory imbibition and pronounced intestinal wall. Suspicious diagnosis was the 1st episode of an uncomplicated diverticulitis of the sigmoid colon associated with an appendicitis epiploica. Therapeutic approach was given by conservative therapy with infusion therapy, analgesia as well as inital “n. p. o.” and following initiation of oral nutrition. In addition, calculated antibiotic therapy with Cefuroxime and Clont was initiated. Clinical course was uneventful, with discharge on the eighth day of hospital stay with no pathological findings and substantial improvement in clinical and laboratory findings. Further advice consisted of clinical and laboratory follow-up control investigations by the family practitioner and nutritional counselling. In addition, a colonoscopy should be performed within four months.ConclusionsThe described case i) is either one of the many side effects of the immunosuppressive medication Mycophenolate mofetil and Tacrolimus listed as “colonic inflammation” and “gastrointestinal inflammation”, respectively, or ii) can be considered an inflammatory response of a susceptible (gastro-)intestinal mucosa or the whole intestinal wall to microbes or microbial particles or agents caused by transplantation-associated immunosuppressive medication.