Abstract
BACKGROUND: Hepatitis B virus (HBV) primarily affects the liver, but increasingly, it is recognized for its potential extrahepatic manifestations. This case highlights the importance of considering viral infections in the differential diagnosis of pulmonary nodules. CASE PRESENTATION: A 63-year-old man presented with a new mixed ground-glass nodule in the left lower lobe during a routine check-up. He had a history of liver resection for hepatocellular carcinoma, with results negative for hepatitis B virus surface antigen. The HBV viral load in the patient's serum was below the detection limit of quantitative PCR (qPCR). Immunohistological analysis of lung biopsy samples indicated chronic inflammation. However, after a course of intravenous antibiotics, the nodule increased in size, prompting further investigation. Therefore, lung biopsy tissue was subjected to metagenomic next-generation sequencing (mNGS), and HBV DNA was detected. The patient was diagnosed with secondary organizing pneumonia associated with HBV. Then he was treated with prednisone acetate and had remission. CONCLUSION: This case underscores the potential for HBV to manifest as pulmonary complications, such as secondary organizing pneumonia. Therefore, in the stage of infectious diseases in patients with a history of hepatocellular carcinoma, HBV needs to be the focus of monitoring, so as to clarify the cause of diagnosis and treatment as soon as possible. CLINICAL TRIAL: Not applicable.