Reliability of cytologic diagnosis of early lung cancer

Baseline screening for lung cancer of 2968 high-risk men and women utilizing HRCT enrolled in ELCAP (Early Lung Cancer Action Project) was performed between 1993-2002. Among them, 65 people had surgical resection of their screen-diagnosed lung cancer, 53 of them on the basis of a diagnosis of malignancy or atypical bronchioloalveolar proliferation (ABP) on fine needle aspiration (FNA) biopsy at Weill Medical College of Cornell University (WMC) prior to surgery. The authors compared the diagnosis obtained from the FNA with the subsequent diagnosis from the surgical specimen to assess the reliability of a cytologic diagnosis of lung cancer on FNA of these screen-diagnosed lung cancers.

The FNA biopsies were performed with a 22-gauge Wescott needle by 1 radiologist (D.Y.), with preliminary on-site as well as final diagnosis rendered by a cytologist (M.V., J.K.). These results were correlated with histologic diagnoses obtained as a result of consensus diagnosis by a panel of 5 expert pulmonary pathologists.

Of the 53 cases of lung cancer resected following FNA, 4 were diagnosed as atypical bronchioloalveolar proliferation (ABP), 14 as adenocarcinoma with bronchioloalveolar features (ADC-BAC), 28 as adenocarcinoma, not otherwise specified (ADC-NOS), 1 as squamous cell carcinoma (SQCC), 4 as nonsmall-cell carcinoma (NSCC), and 2 as typical carcinoid. In the 49 cases with a malignant cytology and 4 cases of ABP, lung cancer was confirmed histologically. The tumor sizes ranged from 4 mm to 40 mm, mean size 13mm. The final expert panel histologic diagnosis was adenocarcinoma in 47 cases; of these, 42 were invasive (mixed subtype or acinar subtype), and 5 were a noninvasive (bronchioloalveolar carcinoma, BAC). Three of the 42 invasive adenocarcinoma that had a predominant BAC component and 1 case of BAC were diagnosed as ABP on FNA; all were sampled at the periphery of the tumor. Three of 4 cases of invasive adenocarcinoma of high nuclear grade were diagnosed as NSCC, and 1 was inaccurately classified as SQCC on FNA. One case of high-grade noninvasive BAC associated with a scar was diagnosed as NSCC on FNA. Two cases classified as nonkeratinizing SQCC and 2 cases of large cell neuroendocrine carcinoma on histology were misclassified as ADC-NOS by FNA. Two cases of typical carcinoid on histology were also diagnosed as typical carcinoid on FNA.

Preoperative diagnosis of lung cancer detected by screening with HRCT could be reliably made by FNA. Difficulty in classification occurs in carcinomas of high nuclear grade with prominent nucleoli, including poorly differentiated SQCC and large cell neuroendocrine carcinoma. These are best diagnosed as NSCC on cytomorphology with further subclassification based on immunohistochemistry, which these authors generally perform on cell-block material. A diagnosis of ABP on FNA may be indicative of noninvasive BAC or an invasive adenocarcinoma with prominent BAC features, usually sampled at its periphery.