Follicular lymphoma (FL) - updated.

Phenotype / cell stem origin Pan-B antigens test positive. The immunophenotypic profile is CD10+, CD5-, sIg+ and the cell of origin is a germinal centre B-cell that has encountered the antigen. Epidemiology This lymphoma accounts for 30-40% of all lymphomas occurring in the adult population in western countries. Its peak incidence is in the fifth and sixth decade. Clinics The patients most often present widespead disease at diagnosis, with nodal and extranodal (bone marrow) involvement. Peripheral blood involvement is detectable by light microscopy in approximately 10% of the cases, but the majority of cases can be shown to have circulating malignant cells by sensitive molecular genetic methods. The disease usually runs an indolent course. Grade 3 FL may be characterized by earlier relapse, especially if treated with regimens not including an anthracycline drug. Pathology The lymphoma is composed of a mixture of centrocytes and centroblasts with a follicular and diffuse pattern. Lymphoma grading by the number of large cells/centroblasts is recommended: three grades are recognized with incresing number of centroblasts. Treatment Depending on age and stage at presentation it may vary from a "watch and wait" policy in initial stages to multiagent chemotherapy in advanced stages. Immunotherapy using chimeric anti-CD20 monoclonal antibody has an important role in combination with chemotherapy. Radioimmunotherapy has an important role in relapsed or refractory patients. Evolution The majority of patients cannot be cured by chemotherapy and eventually relapse. Histologic switch into high grade lymphoma may occur. A positive impact on long term disease free survival and overall survival is likely to derive from the introduction of monoclonal antibodies in association with multiagent chemotherapy. Prognosis Approximately 60% of the patients presenting with limited disease are alive at 10 years. Patients in stages III and IV were reported to have a median survival in the 8-12 years range Cytogenetics Cytogenetics Morphological Seventy-80% of the cases carry the t(14;18)(q32;q21) as the primary chromosome anomaly. Rare variant translocation t(2;18)(p11;q21) and t(18;22)(q21;q11) were described. Approximately 15% of the cases show a 3q27 break, half of which include the t(3;14)(q27;q32) and the variant translocations t(3;22)(q27;q11) and t(2;3)(p11;q27) Cytogenetics Molecular The incidence of 6q21 deletion and 17p13/p53 deletion (see below) by interphase FISH analysis may be around 60% and 20%, respectively Additional anomalies Secondary chromosome changes are both numerical and structural. Trisomy 7, +8; +12, +3, +18, +X each occur in 10-20% of the cases. There is an association between +7 and the presence of a large cell component, but no numerical anomaly has an independent impact on prognosis. Deletions of 6q23-26 occur at a 25-30% incidence; 17p anomalies are present in approximately 10% of the cases. The presence of these anomalies may have a correlation with disease transfornation and it was associated with an inferior prognosis. Rarely, histologic switch into a high grade lymphoma may be associated with the development of an additional t(8;14)(q24;q32). The clinical course in these cases is aggressive The incidence of 6q21 deletion and 17p13/p53 deletion by interphase FISH analysis may be around 60% and 20%, respectively. Other anomalies include 1p36 deletion in 10-12% of the cases, probably centered around the p73 gene; 10q22-24 deletions in 10-13% of the cases and 9p21 deletions/ p16 deletions, associated with histologic transformation