Endometrioid Adenocarcinoma With "Burrowing" Invasion of the Cervix Represents a Separate Primary From the Concurrent Uterine Corpus Endometrial Endometrioid Adenocarcinoma: Histology, Immunohistochemistry, and Next-generation Sequencing Study of a Single Case.

A small subset of endometrial endometrioid adenocarcinoma cases first reported in 2003, showed a distinct cervical component with a so-called "burrowing" invasion pattern. Initially, the cervical component was regarded as cervical involvement by the endometrial adenocarcinoma. However, a 2010 study argued that these cases actually might represent separate primary endometrial and cervical endometrioid adenocarcinomas. However, additional data on this topic are scarce. Here, we report a case of endometrioid adenocarcinoma with a "burrowing" cervical invasion that is morphologically distinct from the patient's endometrial endometrioid adenocarcinoma. By comparing the morphology, immunophenotype, and genetic profile obtained by next-generation sequencing, we demonstrated that the cervical and endometrial tumors were of 2 separate primaries. Our report adds additional data to this unique phenomenon, and will hopefully help to reignite interest in investigating this controversial topic.