Introduction: Intradiaphragmatic abscesses are extremely rare; therefore, making a correct preoperative diagnosis is difficult. Furthermore, their pathogenesis is not well understood because of the limited number of reported cases.
Case presentation: A 62-year-old Japanese male who had undergone cholecystectomy for acute cholecystitis complicated by cholelithiasis 1 year previously presented to our hospital with a fever and right chest pain. Laboratory investigations revealed an elevated inflammatory response. Preoperative computed tomography suggested an intra-abdominal abscess and right pyothorax, and surgical drainage was performed via laparoscopic and thoracoscopic approaches because there was no laboratory improvement after intravenous antibiotic therapy. Intraoperative findings showed a localized bulge in the right diaphragmatic dome without an abscess in the liver or the subdiaphragmatic area. A whitish pus was drained through an incision. By contrast, in the thoracic cavity, serous pleural effusion, fibrin precipitation, and localized bulge on the same diaphragmatic site as the abdominal bulge were found without abscess formation. Pus was not drained by puncture aspiration, and no incision was made. The pus culture was positive for Escherichia coli. A combined abdominal and thoracic approach allows for correct diagnosis and appropriate treatment. The patient's general condition improved postoperatively, and he remained well without evidence of recurrence of the intradiaphragmatic abscess 18 months later for follow-up chest computed tomography.
Conclusions: Despite the extremely rare nature of the disease, if an intradiaphragmatic abscess is suspected preoperatively, a combined abdominal and thoracic approach may be useful for making the correct diagnosis and carrying out appropriate treatment.
Keywords: abscess; intradiaphragm; laparoscopy; rare case; thoracoscopy.
© 2025 The Author(s). Published by Japan Surgical Society.