Multicenter study of diffuse pleural mesothelioma. Histopathological and immunohistochemical features

Medicina 2022 [Link]

Claudia Poleri, Gabriela Acosta Haab, Nora Falcoff, Gabriela Guman, Liliana Dalurzo, Alejandro Iotti, María Eugenia Martín, Gloria Olmedo, Mercedes Rayá, Atilio Reginatto, Andrea Werbach, Gabriela Demelli, María José Labanca, Laura Leguina, María Florencia Mora


The pathological diagnosis of diffuse pleural mesothelioma (DPM) contributes to treatment selection and clinical trials interpretation. To know its characteristics and evaluate the viability of comprehensive pathological diagnosis of DPM in Argentina we did a retrospective descriptive study of DPM cases reported from 2009 to 2018. We analyzed 398 cases corresponding to 238 (60%) men and 160 (40%) women, median age 66 years, from surgical biopsies (78%), small biopsies (16.5%) and surgical resections (5.5%). The 77% were epithelioid (E-DPM), 12% biphasic, 10% sarcomatoid, and 4 cases transitional variant. In E-DPM the main pattern was tubular in 36% and solid in 33%. There was a second pattern in 179 cases. Considering the main pattern and the second together, 48% presented tubular subtype and 48% solid subtype. Stroma, necrosis, and nuclear score showed significant differences between E-DPM and non-epithelioid mesotheliomas. Overall tumor grade was predominantly low in E-DPM, except for 42% of the solid main pattern. We recognized the transitional variant extensively in 4 cases and focally in 8. The immunohistochemical antibody panel used included pan-cytokeratin, calretinin, WT-1, cytokeratin 5, CEA and TTF-1. The expression of cytokeratin 5, calretinin and WT-1 was lower in the sarcomatoid type (43%, 87 and 37%) than in the epithelioid type (92%, 98% and 93%). This study highlights the tumor heterogeneity of DPM that shows the diagnostic difficulty, and the feasibility of evaluating histological aggressiveness in E-DPM, B-DPM and S-DPM in our country.