Gastric-type Adenocarcinoma of the Cervix: Tumor With Wide Range of Histologic Appearances.

Gastric-type endocervical adenocarcinoma (GAS) is a recently described diagnostic entity originally characterized as a tumor with (1) voluminous cytoplasm that is (2) clear or pale eosinophilic, and (3) cells showing distinct cell borders. Since the initial tumor description there has been accumulating experience that the neoplasm, in addition to classic features, may show a wide spectrum of morphologic appearances. This paper describes and illustrates cases of GAS with focal or diffuse findings that include: densely eosinophilic cytoplasm, foamy cytoplasm, goblet cells, glands with elongated, stratified nuclei, glands with small cuboidal cells, glands with flattened cells, papillary growth, single cell infiltration and infiltration with microcystic elongated and fragmented pattern. All these patterns may bring up a differential diagnosis with other cervical malignancies such as usual, intestinal, endometrioid, clear cell, serous, and mesonephric adenocarcinoma. The paper describes the patterns of immunostaining of respective lesions that may aid in the diagnostic process and summarizes the main points of the differential diagnosis. GAS is associated with somatic and germline STK11 mutations and TP53 mutations but is invariably negative for human papilloma virus when tumor only is tested. It shows variation in incidence between countries. Awareness of the spectrum of morphologic appearances in GAS is important for accurate and confident diagnosis. Correct identification of GAS is important due to its propensity for ovarian and other distant metastases, markedly worse prognosis as compared with usual endocervical adenocarcinoma, and its relative resistance to chemotherapy.