[418] Cytologic Diagnosis and Classification of Indolent B-Cell Lymphomas: Results of a 3-Year Institutional Review with Implications for Reporting

Joerg Schwock, Hyang-Mi Ko, Gilda da Cunha Santos, Scott L Boerner, William R Geddie. University of Toronto, Toronto, ON, Canada

Background: The cytologic diagnosis and classification of indolent B-cell non-Hodgkin lymphomas (B-NHL) is considered a challenging area. A range of reported sensitivities and specificities result in clinical uncertainty regarding treatment decisions based on fine needle biopsy (FNB) alone; a situation increasingly encountered with endoscopic ultrasound-guided sampling. We reviewed the records of our institution with the goal of defining specimen characteristics required to render diagnoses according to the WHO classification.
Design: Laboratory records from 2009-2011 were searched for FNB samples with diagnoses or suspected diagnoses of indolent B-NHL (follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, small lymphocytic lymphoma, lymphoplasmacytic lymphoma). Diagnoses, ancillary studies, prior lymphoma history and concurrent/subsequent histological specimens were tabulated. For cases without WHO diagnosis any factors limiting assessment were recorded from the pathology report. GraphPad Prism 5.02 was used for statistical analysis.
Results: 287 cases (231 patients) were identified associated with 105 histologic specimens. A diagnosis according to the WHO classification was rendered in 71.1% (204/287) by cytology. Of 83 cases either lacking subclassification (n=54) or diagnosed as suspicious (n=29), 41 (49.4%) were inconclusive by morphology and immunophenotype, 26 (31.3%) were low in cellularity/hemodiluted, 7 (8.4%) showed equivocal light chain restriction, 6 (7.2%) were submitted in alcoholic fixative and 3 (3.6%) were necrotic. Among lymphoma cases inconclusive by FNB and diagnosed by histology (n=24), an increased proportion of marginal zone lymphomas was found (n=7; 29.2%). 6 of 7 cases with equivocal light chain restriction were confirmed as lymphoma. Cytology-histology agreement was 97.3% when discrepancies due to grading of follicular lymphoma were excluded from the analysis. Ancillary testing by immunophenotyping (p=0.0001) and fluorescence in-situ hybridization (p<0.0001) was significantly associated with subclassified diagnoses.
Conclusions: Cytologic examination of cellular, non-hemodiluted samples in combination with ancillary studies permits a diagnosis according to the WHO classification to be rendered in the majority of cases. Caution is warranted in reporting samples with equivocal features by morphology and ancillary testing. The adequacy of the sample in terms of completeness of required investigations should be stated in the report indicating the certainty of diagnosis.
Category: Cytopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 59, Monday Morning


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