Follicular Non-Hodgkin’s Lymphomas

The follicular non-Hodgkin’s lymphomas are B-cell neoplasms which typically present in an advanced stage, often with bone marrow involvement and diffuse adenopathy. Patients are usually middle aged and asymptomatic at presentation. Many give a history of adenopathy coming and going for several years preceding the pathologic diagnosis. There are three histologic subtypes of follicular lymphoma: follicular small cleaved cell (FSC), follicular mixed small cleaved and large cell (FM), and follicular large cell (FLC) (nodular poorly differentiated lymphocytic, nodular mixed poorly differentiated, and histiocytic or nodular histiocytic, respectively, in the Rappaport classification). Of these, FSC is the most common, comprising about 23% of all non-Hodgkin’s lymphomas. Some studies suggest that there are important differences in the natural course of the disease and response to treatment between the three subtypes while others have failed to confirm these. It is important to recognize that there is great variability in the pathologic criteria and reproducibility in the subclassification of the follicular lymphomas, even among expert pathologists. Futhermore, multiple (discordant) histologic subtypes are found in as many as 20%–30% of patients when more than one biopsy is obtained at diagnosis.