 Because CD20 remains present on the cells of most B-cell neoplasms, and is absent on otherwise similar appearing T-cell neoplasms, it can be very useful in diagnosing conditions such as B-cell lymphomas and leukaemias.However, the presence or absence of CD20 in such tumours is not relevant to prognosis, with the progression of the disease being much the same in either case.CD20 positive cells are also sometimes found in cases of Hodgkins disease, myeloma, and thymoma.