[1328] Reassessment of Small Lymphocytic Lymphoma (SLL) in the Era of Monoclonal B Lymphocytosis (MBL)

SE Gibson, SH Swerdlow, JA Ferry, U Surti, NL Harris, RP Hasserjian. University of Pittsburgh School of Medicine, Pittsburgh, PA; Massachusetts General Hospital, Boston, MA

Background: CLL/SLL according to the 2008 WHO requires either 5x109/L peripheral blood (PB) monoclonal B-cells (MBC) with a CLL phenotype or extramedullary tissue involvement. The diagnosis of SLL is used for non-leukemic cases. Patients not fulfilling these criteria but with CLL-type MBC are diagnosed as MBL. The clinicopathologic features of CLL/SLL with <5x109/L PB MBC now must be reestablished to determine which cases are still best considered CLL/SLL and which, if any, are better considered MBL with extramedullary involvement.
Design: 34 extramedullary tissue biopsies (32 lymph node [LN], 2 other) fulfilling the criteria for CLL/SLL, but with <5x109/L PB MBC were identified and the clinical, pathologic, phenotypic, and cytogenetic findings reviewed.
Results: The 34 patients ranged from 47-88 yrs (M:F=1). 19 biopsies were performed for lymphadenopathy (LAD) and 15 obtained incidentally or for other tumor staging. 26/33 patients had ≥3 sites of LAD (median maximum LN diameter 2.1 cm, 1.0-7.1) on CT (n=30). The median absolute lymphocyte count (ALC) was 2.6x109/L (0.2-7.5) with PB involvement proven by flow cytometry (FC) in 17/17 cases (median MBC count 1.1x109/L). 10/10 patients had bone marrow involvement. Architectural preservation was common in LN, including many open sinuses in 14/29 cases and more than rare germinal centers in 16/30. A focal perifollicular or follicular growth pattern was seen in occasional cases. FC in 18 LN showed 12-89% (median 66%) CLL-type MBC. Cytogenetic studies found del(11q) in 2/17, +12 in 6/17, del(13q) in 5/17, and del(17p) in 5/17 cases. Only 2/20 patients received anti-neoplastic therapy (RX). At a median follow-up time of 12 mos (1-50), 10/20 patients were alive with stable disease, 5 dead of other causes, 2 had disease regression (1 post-MTX withdrawal), 2 had mildly increased LAD (1 post-RX), and 1 achieved a CR post-RX. The maximum ALC doubled in 2/20 patients (at 16 and 25 mos).
Conclusions: CLL/SLL with <5x109/L PB MBC includes a heterogeneous group of patients, most of whom, have an indolent but disseminated disorder with CLL-type cytogenetic abnormalities. Many of these patients could be considered to have MBL with extramedullary tissue involvement resembling so-called "interfollicular SLL"; however, if this differs from early stage CLL/SLL remains to be determined. A small number of cases may represent other indolent lymphomas with a CLL phenotype.
Category: Hematopathology

Monday, March 22, 2010 1:00 PM

Poster Session II # 158, Monday Afternoon


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