HEG1 and malignant mesothelioma: Moreover, Hiroshima et al., looked at the cell blocks of 41 cases of malignant mesotheliomas and 54 cases of carcinomas from various sites (26 lung carcinomas, 21 ovarian carcinomas, and 7 other carcinomas) and found that HEG-1 was positive in all of the mesothelioma cases and negative in 48 of the 54 cases of carcinomas, with six cases of ovarian origin that were positive (6).