This present study, the first to examine both somatic MLH1 methylation and constitutional MLH1 epimutation in sebaceous neoplasms, has provided an important extension of this work demonstrating that somatically acquired MLH1 hypermethylation was not present in the 10 sebaceous neoplasia cases tested, suggesting that this is not a common cause for MLH1/PMS2 MMR-deficiency unlike in CRC and EC. Here, PMS2 is linked to mismatch repair cancer syndrome 1.