Evaluation of the Utility of Liquid-based Cytology, Cell-blocks, and Flow Cytometric Immunophenotyping on Endobronchial Ultrasound-guided Transbronchial Needle Aspiration Samples in the Diagnosis of Sarcoidosis

J Bronchology Interv Pulmonol. 2021 Dec 6. doi: 10.1097/LBR.0000000000000828. Online ahead of print.


Background: There is little information on the value of different processing methods for samples obtained during endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) in suspected sarcoidosis. We evaluated the role of conventional smears, liquid-based cytology (LBC), cell-blocks and flow cytometric immunophenotyping in the diagnosis of sarcoidosis using EBUS-TBNA samples.

Methods: This was a prospective study of consecutive EBUS-TBNA samples from clinically suspected cases of sarcoidosis. In addition to conventional smears, we prepared LBC smears, cell-blocks, and performed flow cytometric evaluation of the CD4:CD8 ratio. The final diagnosis of sarcoidosis was made based on the relevant clinical details and laboratory investigations including the results of transbronchial and endobronchial biopsies (TBLB and endobronchial biopsy).

Results: We included 60 subjects [mean age: 45.2 y; 29 (48.3%) men]. The sensitivity of conventional smears, LBC, and cell-blocks for diagnosing sarcoidosis was found to be 75.5%, 37.8%, 35%, respectively, when used alone. However, on combining conventional and LBC smears, the sensitivity increased to 84.4% and on combining all three techniques, the sensitivity was 86.7%. The CD4:CD8 ratio on flow cytometric immunophenotyping of EBUS-TBNA samples ranged from 0 to 11.5 with a mean of 3.17±2.78 in confirmed cases of sarcoidosis and 70% of these cases had CD4:CD8 ratio of more than 2.

Conclusion: Cell-blocks and liquid-based preparations add to the yield of conventional preparation of EBUS-TBNA samples in the diagnosis of sarcoidosis. A combination of conventional and LBC works well in detecting almost 85% of the cases of sarcoidosis. Higher CD4:CD8 ratio favors a diagnosis of sarcoidosis.