Guidelines for Pathologic Diagnosis of Mesothelioma

Archives of Pathology and Laboratory Medicine 2024 April 8 [Link]

Aliya N Husain, David B Chapel, Richard Attanoos, Mary Beth Beasley, Luka Brcic, Kelly Butnor, Lucian R Chirieac, Andrew Churg, Sanja Dacic, Francoise Galateau-Salle, Kenzo Hiroshima, Yin P Hung, Sonja Klebe, Thomas Krausz, Andras Khoor, Leslie Litzky, Alberto Marchevsky, Kazuki Nabeshima, Andrew G Nicholson, Elizabeth N Pavlisko, Anja C Roden, Victor Roggli, Jennifer L Sauter, Jefree J Schulte, Michael Sheaff, William D Travis, Ming-Sound Tsao, Ann E Walts, Thomas V Colby


Context.—: Mesothelioma is an uncommon tumor that can be difficult to diagnose.

Objective.—: To provide updated, practical guidelines for the pathologic diagnosis of mesothelioma.

Data sources.—: Pathologists involved in the International Mesothelioma Interest Group and others with expertise in mesothelioma contributed to this update. Reference material includes peer-reviewed publications and textbooks.

Conclusions.—: There was consensus opinion regarding guidelines for (1) histomorphologic diagnosis of mesothelial tumors, including distinction of epithelioid, biphasic, and sarcomatoid mesothelioma; recognition of morphologic variants and patterns; and recognition of common morphologic pitfalls; (2) molecular pathogenesis of mesothelioma; (3) application of immunohistochemical markers to establish mesothelial lineage and distinguish mesothelioma from common morphologic differentials; (4) application of ancillary studies to distinguish benign from malignant mesothelial proliferations, including BAP1 and MTAP immunostains; novel immunomarkers such as Merlin and p53; fluorescence in situ hybridization (FISH) for homozygous deletion of CDKN2A; and novel molecular assays; (5) practical recommendations for routine reporting of mesothelioma, including grading epithelioid mesothelioma and other prognostic parameters; (6) diagnosis of mesothelioma in situ; (7) cytologic diagnosis of mesothelioma, including use of immunostains and molecular assays; and (8) features of nonmalignant peritoneal mesothelial lesions.