[1250] Decreased Surface Immunoglobulin Light Chain Expression by Mature B-Lymphocytes in Serous Fluids: An Assessment of Frequency and Clinical Significance

MS Madsen, JH Lunde, R Bryant, MR Lewis. Univ. of Vermont, Burlington

Background: The absence of surface immunoglobulin light chain (sLC) expression by mature B-cells has been found in some cases to be associated with B-cell lymphoproliferative disorders (B-LPD), although this finding is not entirely specific. While the studies addressing this topic to date have largely focused on lymph nodes, we have observed decreased or absent sLC expression in a subset of serous fluid specimens. As the clinical implications of such a finding are uncertain, our experience was reviewed.
Design: Flow cytometric analyses of serous fluid specimens received over a 4.5 year period (1/1/04-6/30/08) were reviewed, yielding 112 specimens from 98 patients (M:F = 52:46; median age 70 y, range 16-99) for which sLC data were available. The specimens were predominantly pleural fluids (90/112 = 80%), with smaller numbers of peritoneal (15) and pericardial (7) fluids. sLC expression was classified as monotypic or not monotypic, and level (brightness) of sLC expression was categorized as absent, minimal/dim, or typical.
Results: Nineteen of 112 specimens (17%) showed monotypic sLC, 20 (18%) contained too few B-cells to permit definitive characterization, and 56 (50%) showed polytypic sLC expression with typical brightness, while the remaining 17 (15%) contained B-cells exhibiting dim or absent sLC expression (6 minimal/dim, 11 absent). 15/17 were pleural fluids, and two were pericardial. Two of these 17 cases showed involvement by lymphoid neoplasms; one showed involvement by a CD5+ B-LPD in a 57 y.o. man who had been previously diagnosed. The second case, involving pleural fluid from an 80 y.o. man with no prior B-LPD diagnosis, contained B-cells that were large by forward scatter and cytologically abnormal, fitting with involvement by DLBCL. Four other cases involved patients with prior or concurrent diagnoses (CLL, DLBCL, B-ALL, classical Hodgkin's) but no evidence of fluid involvement. In the other 11 cases exhibiting dim or absent sLC, no evidence of prior, concurrent, or subsequent involvement by a B-LPD was identified.
Conclusions: 15% of serous fluids contained B-cells that lacked monotypic sLC expression but showed decreased or absent sLC. Among this subset, six cases (35%) were seen in patients with prior or concurrent diagnoses of B-LPD, while eleven (65%) lacked evidence of prior or subsequent involvement by a B-LPD. In our series, absent a positive history or concurrent B-LPD diagnosis, the finding of decreased or absent sLC without monotypia was not associated with subsequent B-LPD.
Category: Hematopathology

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 128, Tuesday Morning