Primary endocervical gastric-type adenocarcinoma: a clinicopathologic and immunohistochemical analysis of 23 cases

Endocervical gastric-type adenocarcinoma (GAS) is a rare non-human papillomavirus-associated adenocarcinoma (NHPVA) with morphologic and immunohistochemical features of gastric differentiation. This study aimed to evaluate cytologic and clinicopathological features, differential diagnosis of endocervical GAS.

A total of 23 patients diagnosed with endocervical GAS/minimal deviation adenocarcinoma (MDA) at Peking University People's Hospital between 2009 and 2018 were included. Clinical characteristics, cytologic/histopathologic findings, and immunohistochemical results were collected and analyzed.

The average age of patients was 51 years old (range from 28 to 73). Cytologically, tall columnar epithelial cells with pale, foamy or vacuolated cytoplasm were mostly common, followed by well-defined cytoplasmic borders. Fourteen endocervical GAS cases demonstrated mild cytologic atypia, and 9 cases showed moderate to marked cytologic atypia. Ovarian and fallopian tube involvement were identified in 5 and 6 cases, respectively. Immunohistochemically, tumor cells were diffusely positive for CK7, MUC6 and CA-IX, but focally positive for CK20 and CDX2. P16 was negative or patchy positive in most cases and p53 mutation was identified in 12 cases (12/21, 57.1%).

Endocervical GAS shows different morphologic and immunological features from endocervical usual type adenocarcinoma, but it may be difficult to be differentiated from metastatic mucinous adenocarcinoma to cervix due to similar morphology and overlapping immunohistochemical profile. Therefore, awareness of the morphologic features and immunohistochemical profile of GAS will allow pathologists to recognize and accurately diagnose this rare and aggressive entity.