Definitive diagnosis of mesothelioma by effusion cytology: Use of the cell transfer method or cell block method for immunochemical staining

Objective: The purpose of this study was to determine whether mesothelioma can be diagnosed definitively by effusion cytology using the cell transfer method or cell block method for immunochemical staining. Study Design: The subjects of this study were 6 patients with mesothelioma diagnosed by effusion cytology in the past 2 years in our hospital. In 5 patients the mesothelioma was located in the pleural cavity and in one patient the mesothelioma was located in the peritoneal cavity. All 6 patients were diagnosed with mesothelioma based on the effusion cytology findings, and immunochemical staining was carried out to make a definitive diagnosis by the cell transfer method in four patients and by the cell block method in two patients. Tumor cells were immunostained with antibodies specific for calretinin, CK5/6, D2-40, thrombomodulin, mesothelin, CEA, MOC31, EMA, E-cadherin, and p53 protein. Results: Staining was positive for calretinin in 6/6 patients (100%), CK5/6 in 6/6 (100%), D2-40 in 6/6 (100%), thrombomodulin in 6/6 (100%), mesothelin in 6/6 (100%), CEA in 0/6 (0%), MOC31 in 0/6 (0%), EMA in 5/6 (83%), E-cadherin in 5/6 (83%), and p53 protein in 6/6 (100%). Based on these findings a definitive diagnosis of mesothelioma was made in all 6 patients. Conclusion: Good immunochemical staining results were obtained, enabling definitive diagnosis of mesothelioma by both the cell transfer method and the cell block method. Immunochemical staining with multiple antibodies is important to making a definitive diagnosis of mesothelioma.