Fine-needle aspiration cytology in the diagnosis and typing of lung carcinomas

Background: New developments in thoracic oncology have challenged the way pathologists approach pulmonary carcinoma. Categorization as small cell or nonsmall cell is no longer adequate, and a distinction between adenocarcinoma (ADC) and squamous cell carcinoma (SqCC) is necessary for specific therapy. Aim: To determine the diagnostic accuracy of fine-needle aspiration cytology (FNAC) in the diagnosis and subtyping of primary lung carcinoma and reliability of the cytological parameters. Settings,Design, and Subjects and Methods: Histologically confirmed lung carcinomas diagnosed on FNAC were evaluated for various cytological parameters by three pathologists, and data were statistically analyzed. Results: A total of 39 cases (22 ADCs, 9 SqCCs, 6 small cell carcinomas and 2 poorly differentiated carcinomas) were studied. The features frequently observed in small cell carcinoma included small cell size (83%), scant cytoplasm (83%), nuclear molding (100%), and granular chromatin with nuclear streaks (67%) in the background. SqCCs showed single cells (66%), distinct cell borders (44%), abundant homogenous cytoplasm (78%), hyperchromatic nuclei (56%), and keratinous debris (22%) whereas ADCs showed glands (45%), three-dimensional (68%) and papillary (23%) clusters, indistinct cell borders (77%), cytoplasmic vacuolation (55%), vesicular chromatin (45%), and mucinous (23%) background. There was a statistically significant agreement between cytologic and histologic diagnosis (P < 0.001) with a very good level of agreement (κ = 0.9). The overall percentage of agreement was 97%, with substantial agreement between the observers (κ = 0.73). Cell size, cohesion, cell borders, molding, chromatin texture, and cytoplasmic characteristics were significantly associated with the diagnosis. Conclusion: Cytologic subtyping of lung carcinoma is feasible and reasonably accurate.