Possible association of pyogenic liver abscess with an inflamed sigmoid colonic lipoma: a case report and literature review

Background Pyogenic liver abscess (PLA) is a severe infectious condition that is often associated with an identifiable biliary or gastrointestinal source. Benign colonic lesions are rarely considered during the etiological evaluation of PLA. Case presentation We report the case of a 47-year-old man admitted with febrile diarrhea. Contrast-enhanced computed tomography (CT) demonstrated confluent hepatic abscesses involving segments II, III, and IV, measuring 10 cm × 9 cm × 7 cm, without a CT-detectable biliary source. The etiological investigation identified an approximately 2 cm inflammatory sigmoid lesion that was initially considered suspicious for malignancy. Laparoscopic oncologic segmental low sigmoid colectomy was performed because malignancy could not be confidently excluded based on superficial endoscopic biopsies. Histopathological examination confirmed a 1.2 cm submucosal lipoma composed of mature univacuolar adipocytes without cytologic atypia, necrosis, or abscess formation. The colonic wall directly opposite the lipoma showed acute neutrophil-rich inflammation extending from the mesocolic/subserosal tissues through the muscularis propria, together with focal superficial epithelial abrasion/erosion of the overlying mucosa and exposure of the lamina propria. Deep or transmural mucosal ulceration, ischemic necrosis, intramural abscess, microorganisms, perforation, and diverticular disease were not demonstrated in the available histopathological sections. Blood cultures were negative. Culture of the hepatic abscess aspirate isolated Klebsiella pneumoniae. The colonic lesion itself was not cultured, and no microbiological or molecular comparison with the hepatic isolate was performed. No phenotypic or molecular testing for a hypervirulent K. pneumoniae phenotype was conducted. Conclusion This case describes a possible association between PLA and an inflamed sigmoid submucosal lipoma with focal superficial epithelial abrasion/erosion. A causal relationship cannot be established from the available evidence. The clinical implication is that colonic evaluation, including colonoscopy when clinically appropriate, may be considered in otherwise unexplained PLA, particularly when no biliary or other common source is identified. This single case does not establish small colonic lipomas as infectious sources of PLA.