RESUMEN
<p><b>OBJECTIVE</b>To evaluate the value of application of cellular protein markers stained by immunocytochemistry in combination with ThinPrep bronchial brush cytology in classification of lung cancer subtypes.</p><p><b>METHODS</b>Remaining bronchial brush cytology samples from 206 lung cancer patients with positive cytological diagnosis and 45 fine needle aspiration samples of resected lung carcinomas were collected. The expressions of CK10/13, CK7, CK18, CD56 and SYN in those samples were detected by immunocytochemistry (ICC) using corresponding antibodies.</p><p><b>RESULTS</b>The sensitivity and specificity of CK10/13 were 94.7% and 72.0%, respectively, in diagnosis of squamous cell carcinoma. The sensitivity and specificity of CK7 were 98.6% and 61.5%, and those of CK18 were 98.6% and 37.5%, respectively, in diagnosis of adenocarcinoma. The sensitivity and specificity of CD56 were 86.3% and 82.9%, and those of SYN were 81.6% and 93.5%, respectively, in diagnosis of small cell lung cancer. No significant difference was found in the expressions of CK10/13, CK7 and CK18 protein markers among differently differentiated lung squamous cell carcinomas and adenocarcinomas (P > 0.05). The classification rate of cytology in combination with ICC in differential diagnosis for 44 cases of unclassified lung cancer reached 90.0% for squamous cell carcinoma, 96.3% for adenocarcinoma, and 100.0% for small cell lung carcinoma.</p><p><b>CONCLUSION</b>Application of cellular protein markers in combination with ThinPrep bronchial brush cytology is helpful to improve the differential diagnosis of lung cancer subtypes, and may become a supplementary diagnostic method in subclassification of lung cancer.</p>