Lymphocytosis

Bernard Greenberg, MD

University of Connecticut Health Center, Farmington, CT

Copyright of the American Society of Hematology, 2006. ISSN: 1931-6860.

This case was reviewed and updated in August 2011 by Dr. Alvin Schmaier and members of the Teaching Cases Subcommittee.

VII. TEACHING POINTS

  1. CLL is an indolent disorder characterized by the proliferation of mature lymphocytes (almost always B lymphocytes).

  2. Patients frequently have lymphocytosis discovered incidentally.

  3. Diagnosis is confirmed by flow cytometry of peripheral blood demonstrating a monoclonal B-cell population (single light chain) expressing markers of B-cell lineage (CD19, CD20 and CD23) as well as aberrant expression of a normal T-cell antigen (CD5).

  4. Prognosis depends on the stage. Many patients do not require treatment initially.

  5. Because of the immunoregulatory deficiencies that are characteristic of this disorder, patients frequently develop viral and bacterial infections as well as autoimmune hemolytic anemia (AIHA) and autoimmune thrombocytopenia. The destruction of red blood cells and platelets is mediated by autoreactive antibodies which probably result from the imbalance of lymphocyte subsets observed in CLL.

  6. CLL is presently considered an incurable disease, thus treatment need not be started unless one or more of the following develop:
    • Symptomatic bulky lymphadenopathy or splenomegaly
    • Fever, night sweats, and/or weight loss
    • Pancytopenia
    • Autoimmune hemolytic anemia and/or thrombocytopenia

  7. In up to 10% of patients, CLL may transform into an aggressive large cell lymphoma (Richter's Syndrome) characterized by fever, night sweats, progressive lymphadenopathy (usually asymmetrical) and frequently, extranodal (e.g., liver) involvement. Less commonly, the transformation is to prolymphocytic leukemia with progressive lymphocytosis, splenomegaly, and night sweats. The prolymphocytes are larger than mature lymphocytes and have abundant cytoplasm and a single prominent nucleolus.

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