BACKGROUND: * A number of important scientific advances can be made through the study of blood, bone marrow, tumor, or other tissue samples from patients with HIV infection, infection with Kaposi s sarcoma associated herpesvirus (KSHV), infection with other oncogenic viruses, or cancer. * This protocol provides a mechanism to affect a variety of such studies. OBJECTIVES: -Acquisition of serum, circulating cells, bone marrow, and tumor or normal tissue samples from participants with HIV infection, KSHV infection, or with cancer. ELIGIBILITY: -Eligibility criteria include age 18 years or older and at least one of the following: Exposure risk to HIV, KSHV, or HPV; HIV seropositive; KSHV seropositive; EBV seropositive; HTLV-1 seropositive; malignancy, Castleman s disease, or skin lesions with appearance of Kaposi s sarcoma; or cervical or anal intraepithelial lesion. DESIGN: * Up to 999 subjects will be enrolled in this study. * Blood samples may be collected at the initial visit, and at follow-up visits. * Other fluids/excretions may be collected (such as urine, saliva, semen, and stool). * Tumor samples may be obtained by fine needle aspirate, by removal of pleural or peritoneal fluid, by skin punch biopsy, or by excisional biopsy, providing the tumor is accessible with minimal risk to the participants. * Specific risks will be described in a separate consent to be obtained at the time of the biopsy. * Samples will be studied in the HIV and AIDS Malignancy Branch, CCR, NCI; laboratories in NCI-Frederick; or those of collaborating investigators.