Clinical application of immunocytochemical detection of ALK rearrangement on cytology slides for detection or screening of lung adenocarcinoma

Immunohistochemical screening of Anaplastic lymphoma kinase (ALK) rearrangement has been regarded essential and routinely carried out to select treatment for lung adenocarcinoma. However, difficulty to approach a tumor by transbronchial lung biopsy (TBLB), it often fails to obtain tumor tissues whereas tumor cells are contained in cytology specimens simultaneously obtained when the bronchoscopy is done. Therefore we evaluated the expression of ALK protein by using immunohistochemistry (IHC) on TBLB specimens and immunocytochemistry (ICC) on brushing smear cytology slides in the same cases, and compared the concordance rate of IHC and ICC results. ICC was carried out on routine Papanicolau-stained slides after cytology diagnosis and decolorization.ResultsEighteen patients with adenocarcinoma were extracted in the Hirosaki University Hospital and the Hirosaki National Hospital. IHC and ICC results showed a very high concordance rate: sensitivity of ICC in comparison with IHC was 85.7% (6/7), specificity was 100% (11/11), positive predictive value was 100% (6/6), and negative predictive value was 91.6% (11/12). Detection of ALK rearrangement using ICC on routine Papanicolau cytology slides is considered to be advantageous for lung cancer treatments.