Abbreviated “ATL” or “ATLL,” this is a rare and particularly aggressive malignancy of blood T-lymphocytes caused by infection with the Human T-cell Lymphotropic Virus (HTLV-I). Individuals diagnosed with this malignancy, unfortunately, do not have a good prognosis, as the malignant cells tend to invade numerous organs and not respond well to aggressive treatment. Blood donors informed of positive HTLV test results grow quite concerned when they do a Google search and read about about ATL (Dr. Google strikes again!). However, most donors with reactive anti-HTLV tests are not truly infected (false positive test), and even if they were, the vast majority of donors who are truly infected will have NO problems whatsoever (including ATL).