Primary Lung Cancer Complicated by Malignant Lymphoma in Two Cases of Epstein-Barr Virus Infection

BACKGROUND: Double cancer is defined as the co-existence of two pathologically distinct cancers. Double cancer consisting of a lung adenocarcinoma and a malignant lymphoma has seldom been reported in time synchronous cases or prior to cases of primary lung cancer, except in those after treatment for malignant lymphoma. CASE PRESENTATION: Case 1 was a 71-year-old woman who was treated at our hospital for chronic hepatitis C, nontuberculous mycobacteria infection, and bronchiectasis. She was diagnosed with a stage IV lung adenocarcinoma (cT1bN2M1b) with a synchronous complicating diffuse large B-cell-type lymphoma. Case 2 was a 62-year-old man who had undergone resection of a stage IB lung adenocarcinoma (pT2aN0M0). Thirty months after the surgery, a diffuse large B-cell-type lymphoma was discovered. In both cases, high antiviral capsid antigen IgG antibody titers were observed. CONCLUSION: Epstein-Barr virus may be associated with the incidence of multiple cancers given the pathological evidence from our two double cancer cases.