Excerpt from Lymphoma, Diffuse Mixed

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In the Working Formulation classification system proposed by a National Cancer Institute working group in 1982, these lymphomas were classified as an intermediate-grade NHL, representing 3-11% of all NHLs.

With the development of immunophenotypic and molecular diagnostics, the Revised European-American Lymphoma (REAL) classification was subsequently proposed and then modified by the World Health Organization (WHO) in 2001. Diffuse mixed lymphoma is now classified as diffuse large B-cell lymphoma. Clinically, patients with this type of lymphoma usually present with advanced and, often, extranodal disease.

Pathophysiology: Diffuse mixed lymphomas are more or less composed of equal numbers of small and large cells. The small cells are usually slightly larger than normal lymphocytes and have a cleaved or indented nucleus and coarse chromatin. The large cells can be cleaved or noncleaved. The cytoplasm of these cells is pale, and the cells have an irregular, central, indented nucleus with inconspicuous nucleoli. A subset of the large cells has rounded nuclei with one or more nucleoli; these are the noncleaved large cells and are somewhat larger compared to the cleaved cells.

Similar to all other intermediate-grade lymphomas, the mixed small and large cell NHLs most often manifest as primary nodal disease, although involvement of the spleen and other organs is common.

Frequency:

• Internationally: Diffuse large B-cell lymphomas comprise approximately 30% of all NHLs.

Mortality/Morbidity: Based on the International Prognostic Index (IPI), patients can be grouped into the prognostic categories of low risk (category 0 or 1), low-intermediate risk (category 2), high-intermediate risk (category 3), and high risk (category 4 or 5). The 5 factors rated in the IPI are age, lactate dehydrogenase (LDH), stage, performance status, and number of extranodal sites.

• For intermediate and aggressive lymphomas, the complete remission (CR) rate for low-risk patients is 87% and the 5-year overall survival (OS) rate is 73%.

• The CR rate for high-risk patients is 44% and the 5-year OS rate is 26%

Sex: This condition affects females more often than males.

Age: Most patients are diagnosed during the seventh or eighth decade of life, with a median age of 63 years.

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