Introduction Among cervical adenocarcinomas, there are variants with worse prognosis such as Gastric-type endocervical adenocarcinoma (GAS) which is important to differentiate from the rest. In this case-control study we performed immunohistochemistry to determine its usefulness in making the diagnosis and possible change in management.

Methods A retrospective case control study was performed in order to determine if the expression of mucins (MUC1, MUC5AC) and claudin18 added to P16 could help in the characterization of gastric type endocervical adenocarcinoma from usual type endocervical carcinoma (ECA). Tissue macro arrays were performed. Clinical characteristics and immunohistochemistry results were compared with inferential statistics.

Results From January 2006 to December 2020, 68 cases were identified, of them 44 were gastric and 24 usual type. Claudin 18 was negative in 23/24 cases of usual type in comparison to 68% of positive in gastric type (p=0.0001), MUC1 was positive in 80% of GAS vs 75% of ECA (p=0.022). P16 was positive in all cases of ECA and one case of GAS. Combining P16 negative and Claudin18 positive had a sensitivity of 100%, Specificity of 53%, a PPV of 56% and NPV of 100% in differencing gastric from usual type adenocarcinoma.

Conclusion/Implications Gastric type endocervical adenocarcinoma is a difficult variant to be identified, with the combination of immunohistochemical markers, such as, Claudin and P16, the diagnosis can be performed with high sensitivity and high Negative Predictive Value, which is clinically relevant in the day-by-day decision making process, since treatment could be modified, specially in locally advanced disease.