[1408] The Significance of Lacking Surface Immunoglobulin Light Chain Expression in B-Cells by Flow Cytometry.

Alireza Zarineh, Samiah Zafar, Thaira Oweity, Jonathan Harris, Sherif Ibrahim, Cynthia Liu. New York University, NY

Background: The value of flow cytometry in the diagnosis of B-cell lymphomas frequently rests upon the ability to demonstrate surface immunoglobulin kappa or lambda light chain restriction, which demonstrates B-cell clonality. Often abnormal B-cell populations are detected which do not express surface kappa or lambda light chains, a common finding recognized in large B-cell lymphomas. We reviewed our flow cytometry cases which had a B-cell population lacking surface light chains in order to determine the significance of such finding in regards to subsequent follow-up data.
Design: This study consists of forty flow cytometry cases reported as having a B-cell population lacking surface immunoglobulin light chain expression from 40 patients over a 3-year period at a tertiary care hospital. Methods of specimen collection included 22 fine needle aspirates (FNA), 7 excisional tissue samples, 8 pleural fluid and 3 peripheral blood.
Results: The follow-up data were available from histology (n=27), and cytologic diagnosis and/or molecular studies (n=13). Upon follow-up review, only 20/40 cases (50%) showed a lymphoma with diffuse large B-cell lymphoma as the leading group (11/20) (See Table).

LYMPHOMA20 (50%)
Diffuse large B cell lymphoma11
Follicular lymphoma2
Marginal zone lymphoma1
Mediastinal large B cell lymphoma1
Chronic lymphocytic leukemia1
T-cell lymphoma1
Nodular lymphocyte predominant Hodgkin lymphoma1
B-cell non-Hodgkin lymphoma, not further specified2
Atypical lymphoid proliferation3
Negative for lymphoma (morphologic and/or molecular diagnosis)12
Metastatic adenocarcinoma5

Conclusions: Although the lack of surface immunoglobulin light chain expression is commonly seen in lymphomas, this phenomenon can also be seen in benign conditions as well as other non-lymphoid malignancies. In such cases the interpretation of flow cytometry in isolation may lead to the erroneous diagnosis of lymphoma. The observation of frequent occurrence of this phenomenon in pleural fluid is interesting.
Category: Hematopathology

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 169, Tuesday Afternoon


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