In other cases, it was the combination of variants that was particularly suggestive of an entity: an example was an abdominal mass with a histological differential diagnosis of sarcomatoid carcinoma of unknown primary or a primary sarcoma (case 16), in which an NF2 mutation with a haploid reduplicated genome was detected, a pattern particularly characteristic of peritoneal mesothelioma [12]. This evidence concerns the gene NF2 and peritoneal mesothelioma.