Chapter 105. Malignancies of Lymphoid Cells (Part 17)

Evaluation of an adequate biopsy by an expert hematopathologist is sufficient to make a diagnosis of follicular lymphoma. The tumor is composed of small cleaved and large cells in varying proportions organized in a follicular pattern of growth (Fig. 105-7). Confirmation of B cell immunophenotype and the existence of the t(14;18) and abnormal expression of BCL-2 protein are confirmatory. The major differential diagnosis is between lymphoma and reactive follicular hyperplasia. The coexistence of diffuse large B cell lymphoma must be considered. Patients with follicular lymphoma are often subclassified into those with predominantly small cells, those with a mixture of...
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Chapter 105. Malignancies of Lymphoid Cells (Part 17) Chapter 105. Malignancies of Lymphoid Cells (Part 17) Evaluation of an adequate biopsy by an expert hematopathologist issufficient to make a diagnosis of follicular lymphoma. The tumor is composed ofsmall cleaved and large cells in varying proportions organized in a follicularpattern of growth (Fig. 105-7). Confirmation of B cell immunophenotype and theexistence of the t(14;18) and abnormal expression of BCL-2 protein areconfirmatory. The major differential diagnosis is between lymphoma and reactivefollicular hyperplasia. The coexistence of diffuse large B cell lymphoma must beconsidered. Patients with follicular lymphoma are often subclassified into thosewith predominantly small cells, those with a mixture of small and large cells, andthose with predominantly large cells. While this distinction cannot be made simplyor very accurately, these subdivisions do have prognostic significance. Patientswith follicular lymphoma with predominantly large cells have a higherproliferative fraction, progress more rapidly, and have a shorter overall survivalwith simple chemotherapy regimens. Figure 105-7 Follicular lymphoma. The normal nodal architecture is effaced by nodularexpansions of tumor cells. Nodules vary in size and contain predominantly smalllymphocytes with cleaved nuclei along with variable numbers of larger cells withvesicular chromatin and prominent nucleoli. The most common presentation for follicular lymphoma is with new,painless lymphadenopathy. Multiple sites of lymphoid involvement are typical,and unusual sites such as epitrochlear nodes are sometimes seen. However,essentially any organ can be involved, and extranodal presentations do occur.Most patients do not have fevers, sweats, or weight loss, and an IPI score of 0 or 1is found in ~50% of patients. Fewer than 10% of patients have a high (i.e., 4 or 5)IPI score. The staging evaluation for patients with follicular lymphoma shouldinclude the studies included in Table 105-11. Follicular Lymphoma: Treatment Follicular lymphoma is one of the malignancies most responsive tochemotherapy and radiotherapy. In addition, tumors in as many as 25% of thepatients undergo spontaneous regression—usually transient—without therapy. Inan asymptomatic patient, no initial treatment and watchful waiting can be anappropriate management strategy and is particularly likely to be adopted for olderpatients with advanced stage disease. For patients who do require treatment,single-agent chlorambucil or cyclophosphamide or combination chemotherapywith CVP or CHOP are most frequently used. With adequate treatment, 50–75%of patients will achieve a complete remission. While most patients relapse (medianresponse duration is ~2 years), at least 20% of complete responders will remain inremission for >10 years. For the rare patient (15%) with localized follicularlymphoma, involved field radiotherapy produces long-term disease-free survivalin the majority. A number of therapies have been shown to be active in the treatment ofpatients with follicular lymphoma. These include cytotoxic agents such asfludarabine, and biologic agents such as interferon α, monoclonal antibodies withor without radionuclides, and lymphoma vaccines. In patients treated with adoxorubicin-containing combination chemotherapy regimen, interferon α given topatients in complete remission seems to prolong survival. The monoclonalantibody rituximab can cause objective responses in 35–50% of patients withrelapsed follicular lymphoma, and radiolabeled antibodies appear to have responserates well in excess of 50%. The addition of rituximab to CHOP and othereffective combination chemotherapy programs is beginning to show prolongedoverall survival and a decreased risk of histologic progression. Trials with tumorvaccines have been encouraging. Both autologous and allogeneic hematopoieticstem cell transplantation yield high complete response rates in patients withrelapsed follicular lymphoma, and long-term remissions can occur. Patients with follicular lymphoma with a predominance of large cells havea shorter survival when treated with single-agent chemotherapy but seem tobenefit from receiving an anthracycline-containing combination chemotherapyregimen plus rituximab. When their disease is treated aggressively, the overallsurvival for such patients is no lower than for patients with other follicularlymphomas, and the failure-free survival is superior.