Cytopathology in focus: Advances in detection of mesothelioma in cytology pleural fluid specimens
August 2022—The ability to make a definitive diagnosis of mesothelioma on pleural fluid cytology has been questioned and debated for a long time. The 2018 American Society of Clinical Oncology clinical guidelines limit the cytological diagnosis of pleural fluid specimens only as an initial screening test for mesothelioma. Monaco, et al., discuss in their article the appropriate use of ancillary studies (immunohistochemistry and fluorescence in situ hybridization studies) to make a definitive diagnosis of mesothelioma in small tissue samples, which are often processed as cell blocks. The authors recommend a stepwise approach starting with immunohistochemistry for BAP1 and, next, MTAP in cases of atypical mesothelial proliferations where the suspicion for malignant mesothelioma is high.