The developing spectrum of gastric-type cervical glandular lesions.

Adenocarcinoma of the cervix is less common than squamous cell carcinoma, although its relative prevalence is increasing. Oncogenic (high-risk) human papillomavirus (HPV) infection is implicated in the development of approximately 90% of all cervical adenocarcinomas. Of the remaining non-HPV associated tumours, the most frequent is gastric-type adenocarcinoma (GAS), which is recognised by the World Health Organization as a form of mucinous adenocarcinoma of the cervix. Minimal deviation adenocarcinoma (MDA) of mucinous type (adenoma malignum) is considered an extremely well differentiated variant of GAS and is encompassed within the category of GAS. The concept of gastric-type cervical glandular lesions has emerged over recent decades and our understanding of the full spectrum of benign, premalignant and malignant lesions is still evolving. Established benign lesions, which are rare, include simple gastric metaplasia and lobular endocervical glandular hyperplasia (LEGH) (complex gastric metaplasia). Postulated premalignant lesions comprise atypical LEGH and gastric-type adenocarcinoma in situ (gAIS); these are probably related lesions for which the umbrella term 'gAIS' has been proposed. The term 'gastric-type' derives from the morphological resemblance of the glandular epithelium to that seen in the stomach and pancreaticobiliary tree; intestinal metaplasia with goblet cells and neuroendocrine cells are present in some cases. A gastric immunophenotype has been demonstrated using markers of pyloric gland mucin, MUC6 and HIK1083. Uncommonly, gastric-type cervical glandular lesions involve multiple sites in the female genital tract and it may be problematic to discern whether these represent independent synchronous or metastatic lesions. There is also an association between gastric-type cervical lesions and Peutz-Jeghers syndrome. Awareness of the spectrum of gastric-type lesions is important, as the diagnostic features of both gAIS and GAS, particularly well differentiated examples, may be subtle, and p16 immunohistochemistry is usually negative. GAS has a much poorer prognosis than HPV-associated cervical adenocarcinoma, with propensity for presentation at advanced stage and wide dissemination to unusual sites such as the ovary, omentum and peritoneum. Although uncommon, GAS is likely to increase in relative prevalence with the introduction of HPV vaccination and precursor lesions will not be detected by primary HPV-based screening programs.