Rare symptom of left inguinal abscess secondary to a retroperitoneal perforation of diverticulitis of the sigmoid colon: A case report

Rationale: Complicated colorectal diverticulitis could be fatal, and an abscess caused by this complication is usually formed at the pericolic, mesenteric, or pelvic abscess. Therefore, we report a rare case of sigmoid colon diverticulitis that developed a large inguinal abscess. Patient concerns: A woman in her 70s was admitted to our hospital with a chief complaint of left inguinal swelling and tenderness 1 week before admission. Physical examination showed swelling, induration, and tenderness in the left inguinal region. Blood tests revealed elevated inflammatory reaction with C-reactive protein of 11.85 mg/dL and white blood cells of 10,300/μL. Contrast-enhanced computed tomography showed multiple colorectal diverticula in the sigmoid colon, edematous wall thickening with surrounding fatty tissue opacity, and abscess formation with gas in the left inguinal region extending from the left retroperitoneum. Diagnoses: The diagnosis was sigmoid colon diverticulitis with large abscess formation in the left inguinal region. Interventions: Immediate percutaneous drainage of the left inguinal region was performed, as no sign of panperitonitis was observed. Intravenous piperacillin-tazobactam of 4.5 g was administered every 6 hours for 14 days. Outcomes: The inflammatory response improved, with C-reactive protein of 1.11 mg/dL and white blood cell of 5600/μL. Computed tomography of the abdomen confirmed the disappearance of the abscess in the left inguinal region, and complete epithelialization of the wound was achieved 60 days after the drainage. The patient is under observation without recurrence of diverticulitis. Lessons: We report a rare case of sigmoid colon diverticulitis that developed a large inguinal abscess, which was immediately improved by percutaneous drainage and appropriate antibiotics administration.