[Value of the blood picture and flow cytometry immunotyping in the early diagnosis of low-grade lymphoma].

Low-grade malignant non-Hodgkin lymphoma [NHL] and chronic lymphocytic leukemia [CLL] as its special form are slowly progressing malignancies which may present with lymphadenopathy, splenomegaly or, more rarely, hepatomegaly. The diagnosis is made by bone marrow or lymph node histology, while laboratory tests are relatively unspecific and may only hint towards the diagnosis. In contrast to high-grade malignant lymphoma, low-grade malignant NHL is often associated with the appearance of malignant lymphoma cells in peripheral blood. These malignant lymphocytes may be differentiated microscopically from normal lymphocytes, so that the diagnosis of NHL may be suspected not only because of clinical symptoms or lymphocytosis, which may present late in the natural history of the disease, but also on morphological grounds. Three types of low-grade malignant NHL cells may be recognized in peripheral blood: A mature appearing lymphocytic type with only slight alterations of the nucleus, a lymphoplasmocytic type, and a lymphocytic type with prominent alterations of the nucleus. The appearance of smudge cells and a monotony in lymphocyte morphology may serve as further diagnostic aids. Once the diagnosis has been suspected on morphological grounds, it may be verified in the case of B-cell lymphomas by flow cytometry. The clonality of T-cell lymphoproliferative disorders in addition has to be proven by demonstrating a clonal rearrangement of the T-cell receptor in Southern blots. An early diagnosis of low-grade malignant NHL may not only provide new insights into the natural history of monoclonal cytopathies but may also be of importance in the clinical management of patients.