Utility of flow cytometry in subtyping composite and sequential lymphoma

Composite lymphoma (CL) is defined as more than one distinct lymphoma varia nt occurring in the same anatomic site, and sequential lymphoma (SL) is def ined as different lymphoma variants occurring at different sites or at diff erent times in the same patient. The utility of flow cytometry immunophenot yping in evaluating CL and SL has only been investigated in a few single-ca se studies. To further define the utility of flow cytometry in evaluating t hese tumors, records were searched at two institutions. Cases representing high-grade progression of low-grade lymphoma were excluded. For each CL/SL, clinical data was obtained and morphology was evaluated in routinely proce ssed H&E-stained tissue sections. Tumor components were subtyped using revi sed European-American classification (REAL) criteria. Follicle center compo nents were graded using modified Rappaport criteria. Immunophenotype was de termined using two-color flow cytometry and paraffin-section immunostains. Four cases were identified. Case 1, nodal follicle center, follicular, grad e III plus marginal zone CL, showed two discrete populations of monoclonal B-cells that differed in their expression of CD10. Case 2, cutaneous lympho plasmacytoid lymphoma followed by mesenteric non-Hodgkin's lymphoma (lympho plasmacytoid plus follicle center, follicular, grade III) plus Hodgkin's di sease CL, showed CD5-/CD10-/CD19+/kappa+ cells by flow cytometry in both ti ssue samples. The Hodgkin's disease component showed CD3-/CD15-/CD20-/CD30 Reed-Sternberg cell variants in paraffin-section immunostains. Case 3 repr esented nodal follicle center lymphoma, follicular, grade I (CD3-/CD5-/CD10 -/CD19+/kappa+) followed by cutaneous anaplastic large T-cell lymphoma (CD2 +/CD4+/CD5+/CD19- cells with partial expression of CD3 and CD7). Case 4 rep resented cutaneous follicle center lymphoma, follicular, grade I (CD5-/CD10 +/CD19+/CD23+/lambda+) followed by bone marrow B-cell small lymphocytic lym phoma (CD5+/CD10-/CD19+/CD23+/kappa+). Results show that flow cytometry is a potentially useful adjunct in characterizing CL and SL. J. Clin. Lab. Ana l. 13:199-204, 1999. (C) 1999 Wiley-Liss. Inc.