University of Vermont Medical Center ICCS Case University of Vermont Medical Center

Clinical History We present the case of a 59-year-old male with a 20-year history of chronic lymphocytic leukemia (CLL) Presented with weight loss, progressive shortness of breath, and an enlarging supraclavicular lymph node CBC: Mild anemia (HGB 11.4 g/dl; MCV 81 fl) WBC 5,800/cmm with 62% neutrophils, 27% lymphocytes, 9% monocytes, 1% eosinophils, 1% basophils PLT 100,000/cmm Biopsy of the supraclavicular lymph node was performed

Recommended Analysis Strategy The following panel was run (Tube 1 and 3 specifically with history of CLL in mind): Tube 1: CD5 PC5 / CD19 ECD / Kappa FITC / Lambda PE / CD45 PC7 Tube 2: CD7 PC5 / CD3 ECD / CD8 FITC / CD4 PE / CD45 PC7 Tube 3: CD20 PC5 / CD23 ECD / FMC7 FITC / CD10 PE / CD45 PC7

Pertinent Findings on Flow Cytometry The most striking abnormality is a population of lambda-restricted, CD45dim, CD19+, CD5+ cells accounting for the majority (80%) of cells These cells fall outside of the normal “lymphocyte gate” as defined by CD45 and SS

Pertinent Findings on Flow Cytometry This population is also CD20+(dim), CD10-, FMC7-, CD23+(subset), HLA-DR+, CD22-

Pertinent Findings on Flow Cytometry By forward scatter, the neoplastic cells are large in size For size comparison, ungated plot showing normal lymphocytes (CD3) vs FS

Diagnostic Considerations Based on flow cytometry results, this case has a classic immunophenotype of CLL (dimCD20, dimCD19, dim surface light chain, CD5+, CD10-, FMC7-, CD23+), and is similar to that seen previously in this patient. CD200 is also classically + in CLL, though is not used at our institution. Increased cell size by forward scatter is concerning for a large cell population. Prominent proliferation centers may contribute to higher side scatter in traditional CLL. Blastic mantle cell lymphoma is a clonal B-cell neoplasm that is CD5+ and CD10- with larger cells, but this would be unusual with this IP pattern coupled with the clinical history. Morphologic correlation is necessary.

Lymph Node Excisional Biopsy

Lymph Node Excisional Biopsy Normal nodal architecture effaced by diffuse population of large cells Ki67 stain shows high proliferation rate ~60-70%

Cytogenetics & FISH Karyotype: 45,X,-Y,t(8;18)(q24;q22),add(9)(q34)[8]/46,XY[2] FISH: MYC and BCL6 rearrangements. Normal BCL2.

Diagnosis Diffuse large B-cell lymphoma, transformed from CLL (Richter transformation), with rearrangements in MYC and BCL6 (“double-hit”)

Case Discussion Richter transformation is the development of an aggressive large-cell lymphoma in the setting of underlying CLL The incidence of Richter transformation has been estimated at 2-9% Most but not all cases of Richter transformation retain the immunophenotype of the original CLL

Take Away Points We present this case to illustrate that CLL not uncommonly transforms into diffuse large B-cell lymphoma In a patient with a history of CLL, the immunophenotype alone will not signal transformation, and simple properties of light scatter can be extremely helpful in making the correct diagnosis Automatic lymphocyte gating may exclude DLBCL populations from analysis, as they often show decreased CD45 expression vs. normal lymphocytes, and careful evaluation is necessary Clinical history (weight loss, rapidly enlarging lymph node, etc.) can increase level of suspicion

References Kroft SH, Dawson DB, McKenna RW. Large cell lymphoma transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma. Hematopathology. 2001;115:385-95. Parikh SA, Kay NE, Shanafelt TD. How we treat Richter syndrome. Blood. 2014;123:1647-57.

Katherine Devitt John Lunde Juli-Anne Gardner Amanda Chamberlain