Case Report: Klebsiella pneumoniae-associated pyogenic spondylitis and occult intrahepatic cholangiocarcinoma during calculous cholangitis

Background Klebsiella pneumoniae is a common Gram-negative pathogen in biliary tract infections and may cause deep-seated infection following bacteremia, although vertebral involvement is uncommon. Severe biliary infection and stone disease may also complicate the recognition of coexisting hepatic malignancy. Case presentation A 51-year-old woman presented with calculous acute obstructive suppurative cholangitis complicated by septic shock and multiorgan dysfunction. Blood and bile cultures yielded Klebsiella pneumoniae , and her condition improved after urgent biliary drainage and antimicrobial therapy. During a subsequent admission, she developed progressive low-back pain. Lumbar magnetic resonance imaging showed abnormalities involving the L3/4 vertebrae and adjacent paravertebral tissues, initially raising suspicion of spinal tuberculosis. Vertebral biopsy demonstrated focal suppurative inflammation, and metagenomic next-generation sequencing of the same tissue detected 33,735 K. pneumoniae -specific reads, with a relative abundance of 82.18% and genome coverage of 59.7%, together with multiple hypervirulence-associated determinants. These findings supported a diagnosis of K. pneumoniae -associated pyogenic spondylitis. Meanwhile, serial hepatobiliary imaging showed regression of the right hepatic abnormalities as the infection improved, whereas a focal lesion in the left liver persisted. Subsequent imaging raised suspicion of cholangiocarcinoma, and histopathologic examination after surgical resection confirmed poorly differentiated intrahepatic cholangiocarcinoma. Conclusion This case underscores the importance of maintaining diagnostic vigilance even after an initial diagnosis has been established. New focal symptoms or abnormalities that persist or follow a different clinical course should not be automatically attributed to the original disease process, and the possibility of additional coexisting diagnoses should remain under consideration.