Ask the Expert: The Difference Between CLL Stage and SLL Stage

In our new series of, “Ask the Expert” blog posts we hope to answer any questions our readers may have regarding lymphoma or oncology. If you have a question please email us, and one of our experts will do their best to answer your question on our blog. We always like to hear from our readers in the hope that our expertise can provide general guidance, context, and clarity. We will not include any names and may paraphrase any questions to remove details that might be personal or identify the sender. We cannot provide specific management recommendations. If you have serious concerns about your health you should see a medical professional in person.


What is the difference between CLL stage (Rai or Binet) and SLL stage (Ann Arbor)? Why does the same disease have two different staging systems?


Dr. Richard Furman, M.D.
Dr. Richard Furman, M.D.

Dr. Richard Furman writes: The purpose of a staging system is to help clinicians better determine prognosis and plan treatment for a patient’s disease. Although chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are the same disease, they were not recognized as the same disease until 1994. Since then they have been combined into one entity, CLL/SLL.

For historical reasons, CLL was staged based upon the Rai or Binet scheme (see below) and SLL was staged using the Ann Arbor lymphoma staging scheme (see below). Today most CLL specialists use the Rai stage because it is more clinically helpful. Using the Ann Arbor classification to stage SLL is problematic in scenarios where the disease has spread to the bone marrow. A person with SLL in their lymph nodes and bone marrow would immediately be characterized as an Ann Arbor stage IV, but their prognosis and treatment plan would be far better indicated as measured by the Rai stage I. Therefore the Rai stage, even without lymphocytosis, provides better prognostic and therapeutic information for a physician to treat their patient.

Rai Stages

0: lymphocytosis (an increase in number of lymphocytes in the blood).

I: Lymphocytosis + lymphadenopathy, (enlarged lymph nodes).

II: Lymphocytosis + splenomegaly (enlargement of the spleen) +/- lymphadenopathy

III: Lymphocytosis + anemia (decrease in red blood cells) +/- splenomegaly +/- lymphadenopathy

IV: Lymphocytosis + thrombocytopenia (decrease in platelets) +/- anemia +/- splenomegaly +/- lymphadenopathy

Ann Arbor Stages

I: Disease found in one group of lymph node

II: Disease found in two or more groups of lymph nodes on the same side of the diaphragm.

III: Disease found in two or more groups lymph nodes on both sides of the diaphragm.

IV: Extranodal disease (found outside of the lymph nodes), including bone marrow, liver, or other organs)

Note: if only one isolated area or organ involvement is present, then it would be a stage I, except for bone marrow.

Author: lymphomaprogram

Located on the Upper East Side of New York City, the Lymphoma Program at Weill Cornell Medical College/NewYork Presbyterian Hospital is internationally recognized for our efforts to enable patients with non-Hodgkin lymphoma, Hodgkin disease and related disorders to have the best possible clinical outcome, including cure when possible.

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