The authors proposed a mesothelioma weighted grading scheme (MWGS) ranging from 0 to 10 based on the patient’s age (≤74, >74 yrs: scores 0, 1); histologic type (epithelioid, biphasic, sarcomatoid: scores 0, 1, 2); necrosis (absent, present: scores 0, 2); mitotic count per 2 mm2 (≤1, 2 to 4, ≥5: scores 0, 1, 2); nuclear atypia (mild, moderate, severe: scores 0, 1, 2); and BAP1 expression (lost, retained: scores 0, 1). This evidence concerns the gene BAP1 and mesothelioma.