ALK and adenocarcinoma: Adenocarcinoma cells in the pleural effusion were also negative for LUAD specific oncogenic driver mutations: EGFR mutation and ALK translocation determined using the PCR-invader method [11] and the intercalated antibody-enhanced polymer (iAEP) method (HISTOFINE ALK iAEP® kit, Nichirei Biosciences, Inc., Tokyo, Japan) [12], respectively.