Monoclonal antibody against CD20 (rituximab) is used to treat patients with B-cell malignant lymphomas that express CD20. Sometimes a patient treated with lymphoma will develop a recurrence of lymphoma with CD20-negative cells.



(1) history of B-cell malignant lymphoma that expresses CD20

(2) prolonged therapy with rituximab

(3) development of a malignant lymphoma that is CD20 negative


Possible explanations

(1) reversible suppression of CD20 expression

(2) selection of CD20-negative clone of same tumor (possibly through deletion of the CD20 gene)

(3) progression to a more aggressive form of lymphoma that is CD20 negative


New Lymphoma

Change After Stopping Rituximab


same as original

lymphocytes become CD20 positive

reversible suppression

same as original

lymphocytes stay CD20 negative

selection of CD20 negative clone

different and higher grade


progression to more aggressive lymphoma


To read more or access our algorithms and calculators, please log in or register.