Recent research has revealed that mesotheliomas frequently exhibit loss of BAP1, which is more common in the epithelioid subtype, and/or loss of CDKN2A, which is relevant to the differential diagnosis of the epithelioid subtype versus mesothelial hyperplasia and sarcomatoid subtype versus reactive fibrous pleuritis (more common in sarcomatoid subtype). Here, BAP1 is linked to mesothelioma.