RESUMEN
A 76-year-old Japanese man was admitted to our hospital with chills and fever. Computed tomography revealed a 10-cm cystic tumor with peripheral ring enhancement in the left lobe of the liver and several small low-density areas with early peripheral enhancement in both lobes. The large liver mass was diagnosed as a pyogenic abscess and treated with antibiotics. However, elevation of the tumor marker, PIVKA-II, raised the possibility of hepatocellular carcinoma. A fine-needle aspiration biopsy was performed, and malignant hepatic cells were identified. The patient underwent left hepatectomy. Histological analyses of the resected surgical specimen confirmed necrotic liver abscess and residual hepatocellular carcinoma with massive lymphoid cell infiltration. Immunohistochemical analyses revealed that the lymphoid cells were positive for CD3 and CD8. The PIVKA-II level returned to normal after surgery and the hepatic lesions disappeared within 10 months. These findings suggest that the liver abscess stimulated cancer immunity, resulting in the proliferation of cytotoxic T lymphocytes and, subsequently, tumor regression.