Occult metastatic non-small cell lung cancer presenting as sepsis with multi-organ dysfunction: a diagnostic challenge, a case report

A previously healthy older adult presented with progressive lower-extremity oedema, generalised weakness, and fatigue. On admission, she was febrile, tachycardic, and hypotensive, with confusion and proximal muscle weakness. Laboratory tests indicated leukocytosis, elevated lactate, and acute kidney injury. Chest imaging showed a dominant hilar mass with bilateral infiltrates and pleural effusions; abdominal scans revealed multiple hepatic lesions and ascites; head imaging identified a solitary brain metastasis. Despite prompt broad-spectrum antibiotics and intensive support, her condition deteriorated, and all cultures remained negative. A liver biopsy confirmed metastatic pulmonary adenocarcinoma, consistent with non-small cell lung cancer. The patient developed cancer-associated thrombosis and later Clostridioides difficile colitis. Given relentless decline and poor prognosis, care was transitioned to comfort measures. This case highlights the diagnostic overlap between infection-driven sepsis and malignancy-related systemic inflammation. When sepsis does not respond as expected and microbiological workup is unrevealing, clinicians should suspect occult cancer, pursue early imaging and biopsy, and involve multidisciplinary teams to align treatment with patient values.

The work titled “Occult Metastatic Non-Small Cell Lung Cancer Presenting

as Sepsis with Multi-Organ Dysfunction: A Diagnostic Challenge, a Case Report”, was published on Malignancy Spectrum (published on June 30, 2026).