[1936] Cytologic-Histologic Correlation of Lung Adenocarcinoma Subtyping

Erika F Rodriguez, Sara Monaco, Sanja Dacic. University of Pittsburgh, Pittsburgh, PA

Background: The significance of histological subtyping of surgically resected lung adenocarcinoma (ADC) was recently proposed by the IASLC/ATS/ERS classification. Approximately 70% of lung cancer patients present with advanced disease and small biopsies or cytology specimens are the only available diagnostic material. It is uncertain if proposed morphologic subtying of ADC can be applied to small specimens.The aim of this study was to assess the applicability of morphological subtyping of lung adenocarcinoma on cytologic specimens.
Design: 133 consecutive newly diagnosed primary lung ADC from patients who underwent surgical resection were selected for the study. 66 patients had 66 positive cytologies available for review. All surgical resection and cytology specimens were reviewed and the dominant morphologic pattern was determined according to the IASLC/ATS/ERS classification. The number and percentage of malignant cells in cytology specimens were also evaluated.
Results: Cytology specimens included FNA (n=61), pleural fluid (n=3), and bronchial lavage (n=2) specimen. Twenty nine(44 %) cases had an estimated >300 neoplastic cells, 27 (41%) had 200-100 cells, and 10 (15%) had ≤50. Concordant subtyping of ADC between resection and cytology specimens was observed in 37 cases (56%) which were classified as acinar (n=26), solid (n=7), mucinous (n=2), and papillary (n=2). Discordant subtyping was seen in 21(32%) cases. The predominant pattern in resections with discordant cytologies was solid (n=6) followed by acinar (n=5). Eight cases were not possible to classify on cytology due to scant cellularity (n=3) or indefinite patterns (n=5). Cellularity did not seem to affect cytologic-histopathologic correlation. Of the 29 cases with >300 neoplastic cells, 19 (66%) showed correlation, and 6 of 10 cases (60%) with ≤50 cells.
Conclusions: Application of the 2011 IASLC/ATS/ERS ADC classification to cytologic specimens of pulmonary adenocarcinoma is feasible, although the concordance varies by histologic subtype. Future studies are needed to establish reproducible cytologic criteria for precise subtyping of lung ADC on small specimens.
Category: Pulmonary

Monday, March 4, 2013 1:00 PM

Poster Session II # 288, Monday Afternoon


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