A case of chronic hepatitis B complicated by systemic sarcoidosis that regressed following nucleos(t)ide analog therapy.

Herein, we report the case of a 75-year-old woman with systemic sarcoidosis complicated by chronic hepatitis B. She presented with high fever and fatigue, with imaging studies revealing multiple tumor nodules in the liver and spleen, along with generalized lymphadenopathy, leading to her admission to our hospital for further evaluation and treatment. Blood tests revealed chronic hepatitis B, and nucleoside analog therapy with entecavir was initiated before the sarcoidosis diagnosis. A liver biopsy confirmed sarcoidosis, and treatment continued without steroid use. Significant improvement in symptoms and tumor size reduction were observed within weeks. After 6 months of treatment, positron emission tomography/computed tomography showed further regression of the liver and spleen tumors, with no symptom recurrence. Given the rarity of sarcoidosis complicated by chronic hepatitis B, this case suggests that controlling hepatitis B virus infection with nucleos(t)ide analogs might improve sarcoidosis symptoms without steroid use. The immunologic mechanisms underlying this cooccurrence remain unclear, and such cases are extremely rare. Therefore, this case may contribute to the understanding and management of sarcoidosis in patients with concurrent chronic hepatitis B.