A case of acute appendicitis in a patient with minimal change disease.

Minimal change disease (MCD) is a common cause of idiopathic nephrotic syndrome (NS). MCD patients are complicated by acute kidney injury (AKI). Gastrointestinal disorders also occur during the course of NS; however, acute appendicitis after the development of NS has not been reported previously in patients with MCD. We report the case of a 54-year-old Japanese man with MCD who was diagnosed with acute appendicitis after developing NS. The patient visited a nearby medical clinic with abdominal distension, decreased urine volume, and edema of the face and lower limbs. As the symptoms did not improve and he developed abdominal pain, he was referred to the Division of Gastroenterology at our hospital. Hypoalbuminemia and proteinuria were detected, and he was introduced to our division and admitted for the evaluation and treatment of NS. After admission, right lower quadrant abdominal pain and rebound tenderness occurred, and an enlarged appendix and increased fat tissue density around the appendix were observed on abdominal and pelvic computed tomography. The patient underwent laparoscopic appendectomy for suspected acute perforated appendicitis and peritonitis. Although the patient required temporary hemodialysis due to oliguric AKI, the renal function and proteinuria improved with steroid therapy. We performed a renal biopsy, which revealed MCD with acute tubular injury. Since severe gastrointestinal disorders can occur in patients with MCD, these patients should be followed-up with carefully for acute abdominal pain. The prompt management of gastrointestinal disorders is important when acute abdominal pain occurs in patients with MCD.