The diagnostic value of cell block as an adjunct to liquid-based cytology of bronchial washing specimens in the diagnosis and subclassification of pulmonary neoplasms.

Background: To the authors' knowledge, the diagnostic value of cell block (CB) as an adjunct to ThinPrep liquid-based cytology (LBC) of bronchial washing specimens in the detection and subclassification of pulmonary neoplasms has not been well evaluated. The objective of the current study was to evaluate the diagnostic utility of CB in this setting.

Methods: A total of 74 bronchial washing specimens and concurrently prepared CBs with a diagnosis of malignant or suspicious/atypical obtained from bronchoscopy procedures performed during 2009 were reviewed along with 28 randomly selected negative cases. LBC and CBs were reviewed independently. Deeper levels and ancillary studies were performed on CBs for specific tumor classification if needed. LBC and CB diagnoses were correlated with final histology and/or bronchial brushings.

Results: Use of CBs increased the number of positive diagnoses from 18 (LBC only) to 30 (combined LBC and CB) and 36 (combined LBC and CB with ancillary studies), with increased diagnostic yields of 67% and 100%, respectively. CB without ancillary techniques detected 22 malignancies whereas LBC detected 18 malignancies and CB with ancillary techniques detected 29 malignancies. A specific tumor diagnosis was possible in 22 of 29 (76%) malignancies detected by CB. Bronchial brushings and histology confirmed malignancy in 91% and 92% of cases, respectively.

Conclusions: CB combined with LBC was found to improve the rate of detection of malignancy over LBC alone, especially in cases with suspicious or atypical LBC diagnoses. Increased diagnostic yield is observed when CB is used with or without ancillary studies, but the yield is higher with CB using ancillary studies. CB serves as yet another available source of diagnostic material for immunohistochemical and molecular studies.