CHICAGO – A 50-year old otherwise healthy man was found on routine history and physical to have lymphocytosis and was referred for additional work-up. He denied recent infection, had no lymphadenopathy, organomegaly, or rash or other concerning skin lesions. A complete blood count showed a white cell count of 23 x 109/Land absolute lymphocyte count of 19 x 109/L and normal hemoglobin and platelets.
Based on recently updated International Workshop on Chronic Lymphocytic Leukemia (iwCLL) guidelines, additional work-up for this patient might include peripheral smear and flow cytometry, according to Paul Barr, MD.
“A peripheral smear is still useful in this day and age just to ensure that a patient has a typical look under the microscope. We expect to see small mature lymphocytes, smudge cells, and perhaps a smaller number of prolymphocytes. But to mark CLL based on flow cytometry we need to see greater than 5 x 109/L clonal B lymphocytes in the peripheral blood sustained over time,” Dr. Barr, medical director of the clinical trials office for Wilmot Cancer Institute at the University of Rochester (N.Y.), said during a presentation at the American Society of Hematology Meeting on Hematologic Malignancies.
A nuance in the iwCLL guidelines is that CLL also can be defined by a cytopenia caused by a typical marrow infiltrate, regardless of the number of circulating B lymphocytes, he noted.
Immunophenotype
As for CLL immunophenotype, the cells are CD5- and CD23-positive, and additional B cell markers like CD20 are “often dim, and – understandably – the cells are light-chain restricted,” he said.
A subtle difference between the World Health Organization classification of CLL and the iwCLL guidelines is that, by the former, patients can have “a somewhat atypical immunophenotype.”
“So our pathologists, I like to think, use a commonsense approach where, if there are very minor differences, they will still call it CLL, but not if there are major differences in the immunophenotype,” Dr. Barr said.
Patients with lymphadenopathy, without the critical threshold of circulating B lymphocytes, are considered to have small lymphocytic lymphoma (SLL).
“In this day and age we treat CLL and SLL relatively similarly, however, monoclonal B lymphocytosis (MBL) is the precursor lesion to CLL where we see less than 5 x 109/L of circulating B lymphocytes and an absence of adenopathy and disease-related cytopenias,” he noted.
Staging
It is still common practice to stage patients given the prognostic value of staging and given that treatment is provided in advanced disease, Dr. Barr said.
“This is simple, easy to apply, applicable worldwide, and only requires laboratory testing and a physical exam,” he said.
The stages include:
- Stage 0: Lymphocytosis, peripheral lymphocyte count greater than 15,000/mcL and greater than 40% lymphocytes in bone marrow (low-risk disease status).
- Stage I: Stage 0 disease plus enlarged lymph nodes (intermediate-risk disease status).
- Stage II: Stage 0-I disease with splenomegaly and/or hepatomegaly (intermediate-risk disease status).
- Stage III: Stage 0-II disease with hemoglobin less than 11g/dL or hematocrit less than 33% (high-risk disease status).
- Stage IV: Stage 0-III disease with platelet count less than 100,000/mcL (high-risk disease status).