Sensitive molecular testing methods can demonstrate NSCLC driver mutations in malignant pleural effusion despite non-malignant cytology

Cytology is currently the standard method of diagnosing malignant pleural effusion (MPE), however the sensitivity is approximately 60–70%, and is dependent upon tumour load, volume of fluid assessed and cytopathologist experience (1,2). Lung adenocarcinoma is the commonest cause of MPE and following cytologic diagnosis, molecular testing of MPE cell block specimens is feasible (3-5)