Data for HEG1, derived from four laboratories, showed membrane staining in only 393 of 434 (91%) epithelioid/biphasic mesotheliomas in contrast to previous study that reported 97% of postivity and this may be due to dissimilar cohort number or different methods of positivity interpretation. On the other hand, only one case of 360 (0.3%) NSCLC showed HEG1 positivity (sensitivity 91%, specificity 99.7%) (12). This evidence concerns the gene HEG1 and mesothelioma.