BMD-B 2011: Evaluation for Non-Hodgkin Lymphoma in the Bone Marrow

In patients newly diagnosed with malignant lymphoma, examination of the bone marrow, along with the performance of routine laboratory testing, is among some of the tests needed to determine extent of disease prior to initiation of therapy. A bone marrow examination can also be performed in patients in whom a clinical suspicion of lymphoma is present, but cannot be confirmed due to nondiagnostic lymphoid infiltrates in other sites, inaccessibility for biopsy in extramedullary locations, or to assess response to therapy if the marrow was initially involved. The marrow can often be the site of primary diagnosis in a patient with unexplained cytopenias. When a bone marrow examination is performed for staging of the patient, a complete blood count, along with a white blood cell differential, is also typically ordered. An absolute lymphocytosis may be present in the peripheral blood, such as with chronic lymphocytic leukemia/small lymphocytic lymphoma. Morphologic examination of the peripheral blood smear can also be useful in identifying atypical lymphoid cells in patients without an absolute lymphocytosis; this may be indicative of peripheral blood involvement by lymphoma. Malignant lymphoma cells in the peripheral blood can be seen in about 10% of all patients with non-Hodgkin lymphoma (NHL) at diagnosis, and careful review of the nuclear characteristics, cell size, and cytoplasm of lymphoid cells in the peripheral blood smear is required in these patients. Splenic marginal zone lymphoma cells can often be present in the blood at the time of diagnosis; therefore, it is important to be familiar with the type of lymphoma to determine the likelihood of blood or marrow involvement. The presence of circulating lymphoma cells can also occur in patients with a longstanding history of lymphoma and can be indicative of extensive marrow involvement and disease progression. Flow cytometry studies on the peripheral blood can be useful in confirming a morphologic impression of lymphoma in the blood.