[386] Diagnoses of Squamous Cell Carcinoma and Adenocarcinoma of the Lung Using Cytology Specimens: A Retrospective Review with Biopsy Correlation

HS Ladenheim, MO Idowu, RC Fries, CN Powers. VCUHS/MCV Campus, Richmond, VA

Background: In view of the EGFR dependent targeted therapy for adenocarcinoma of the lung, the diagnosis of non-small cell carcinoma (NSCC) on cytology specimens is no longer adequate. There is an increased need to differentiate between squamous cell carcinoma (SCCa) and adenocarcinoma (AdCa) of the lung. The purpose of this study is to determine rate of cytologic diagnosis of adenocarcinoma and squamous cell carcinoma of the lung, correlation of cytologic diagnosis with lung biopsy specimens and as well as to determine the value of cytology in making this distinction.
Design: We retrospectively reviewed all pulmonary cytologic specimens (bronchial washings, bronchial brushings, bronchial alveolar lavage and fine needle aspirations) from 2000 to 2007. Only cases cytologically diagnosed as SCCa, AdCa, NSCC favor SCCa, NSCC favor AdCa and NSCC not otherwise specified were included in the analysis and correlated with corresponding and or follow up biopsy diagnoses.
Results: There are 5296 cytology lung specimens over the 7-year period. 823 (15.5 %) of these were diagnosed as malignant. 659/823 (80%) as NSCC, 103/823 (12.5%) were diagnosed as small cell carcinoma, 22 (2.7%) as metastatic carcinoma, 36 (4.4%) as carcinoma NOS and 3 (0.4%) as carcinoma with neuroendocrine features. Of the 659 cases of NSCC, 214/659 (32.5%) were diagnosed as SCCa/NSCC favor SCCa, 68 (10.3%) were diagnosed as AdCa/NSCC favor AdCa, while the remaining 377 (57.2%) were diagnosed as NSCC NOS. Surgical follow-up for the non small cell carcinoma was present in 196/659 cases (29.7%). All the surgical specimens were biopsies with only 2 lobectomies. There was 82% and 84.6% correlation with the biopsy specimens in SCCa and AdCa respectively.

Table 1. Cytologic diagnoses with follow-up or concurrent biopsies

	SCCa biopsy	AdCa biopsy	NSCC NOS biopsy	Benign bronchial mucosa	Hamartoma
SCCa Cyto (n=67)	55 (82%)	1 (1.5%)	4 (6%)	6 (9%)	1 (1.5%)
AdCa Cyto (n=13)	0	11 (84.6%)	0	2 (15.4%)	0
NSCC NOS cyto (n=225)	39 (17.3%)	47 (20.9%)	110 (48.9%)	29 (12.9%)	0

Conclusions: There is a good surgical pathology correlation between cytologic diagnosis of adenocarcinoma and squamous cell carcinoma. Due to sampling error on biopsy, there is an increased chance for a diagnosis of carcinoma on cytologic specimens. Therefore since cytology may be the initial specimens obtained for diagnosis, subclassification of non small cell carcinoma, may obviate the need to obtain additional surgical biopsy for diagnosis.
Category: Cytopathology

Monday, March 9, 2009 2:00 PM

Platform Session: Section F, Monday Afternoon