Type B thymoma in a patient with HIV infection: A case report with a review of HIV and thymoma coexistence.

HIV infection predisposes people to cancer, including AIDS-defining cancers, such as Kaposi sarcoma, and a broad range of non-AIDS-defining cancers. Here we report a case with rare coexistence of HIV and thymoma, and summarize all the comorbid cases that currently exist. We found that in all the cases reported, thymoma occurred when CD4+ counts were within a normal range, but the immune response in peripheral T-cell repertoire remains unknown. In our case, an overview of the immune system under this complicated situation is given for the first time by showing the lymphocyte subpopulations in the blood and the immune cell distribution of the thymoma. This case expands the scope of non-AIDS-defining cancers, and provides insight into the influence of the immune system under two immunocompromising conditions, HIV infection and thymoma.