Gastric-type mucinous carcinoma of the cervix and its precursors - historical overview

The emerging concept of gastric-type mucinous carcinoma (GAS) of the uterine cervix has been accepted worldwide because of its aggressive clinical behaviour and the absence of high-risk human papillomavirus (HPV). GAS is included as a variant of mucinous carcinoma in the 2014 World Health Organization classification, and its recognition has provoked a discussion on endocervical adenocarcinoma as a single entity such that endocervical adenocarcinoma is now divided into HPV-associated and HPV-independent groups. This article reviews historical and conceptual aspects of GAS and its precursors, starting with minimal deviation adenocarcinoma (MDA), through the ensuing confusion, up to the recent paradigm shift in cervical adenocarcinoma subclassification. The gastric immunophenotype of MDA was demonstrated by a Japanese group in 1998 using the HIK1083 antibody, which recognises gastric pyloric gland mucin, and this elucidated the pathogenesis of this particular tumour. However, this information resulted in overdiagnosis of lobular endocervical glandular hyperplasia (LEGH), first described in 1999 and which represents pyloric gland metaplasia (PGM), as malignant. In the early 2000s the relationship between MDA and LEGH/PGM became a matter of controversy. In 2007 HIK1083 immunohistochemistry extended the morphological spectrum of endocervical adenocarcinoma showing gastric differentiation beyond MDA, which resulted in the proposal of GAS as a distinct entity including MDA as its very well-differentiated subtype. GAS is now considered to be an aggressive and chemoresistant neoplasm that is not related to high-risk HPV. The LEGH/PGM-GAS sequence is currently regarded as an HPV-independent pathway of carcinogenesis. Understanding the underlying molecular events in this process is key to the development of biomarkers for early detection and molecular targeted therapy.