Case 9 : Mesonephric hyperplasia

A 46-year-old lady was diagnosed with adenocarcinoma in situ on pap smear and she underwent cervical cone biopsy. One representative section.

​Educational notes: 1. Section from the cervical cone biopsy shows mesonephric hyperplasia characterized by lobules of glands in the deeper part of the cervical wall. These glands are composed of a single layer of cuboidal epithelium without cytological atypia. The covering squamous epithelium and endocervical glands are devoid of dysplasia. 2. Presence of lobules of glands in the deeper part of the cervical wall stimulates infiltrative adenocarcinoma. However, entities such as mesonephric remnants and mesonephric hyperplasia need to be considered. Mesonephric remnants typically involve the deep layer of anterolateral wall of cervix along the path of the mesonephric duct. They may appear infiltrative and extend close to the luminal surface and intermingle with endocervical glands. In contrast, mesonephric hyperplasia has larger and more irregularly distributed glands as compared to mesonephric remnants. In the lobular type, the glands have exaggerated, clustered, lobular arrangement separated by variable amount of stroma. In the diffuse type, mesonephric hyperplasia displays predominantly non-clustered, extensive, and more diffuse proliferation. The least common duct type is characterized by hyperplastic epithelium with papillary tufting, and it may show clefted contours lacking intraluminal secretions. 

3. Mesonephric glands are characteristically lined by a layer of simple flat or low cuboidal, non-ciliated cells with distinct basement membranes. They contain PAS-positive, diastase resistant material. Differing from adenocarcinoma or adenocarcinoma in situ, mesonephric glands lack nuclear atypia. Adenocarcinoma in situ is consistently characterized by nuclear enlargement, coarse chromatin, small single or multiple nucleoli, increased mitotic activity and variable nuclear stratification. An invasive adenocarcinoma shows complex architecture forming labyrinth or maze-like arrangement, and cribriform pattern with single gland profile. Although presence of stromal desmoplasia favors malignancy, distinction from a range of benign conditions showing stromal fibrosis, oedema and dense inflammation is critical.

​Reference 1. Zaino, R. Glandular Lesions of the Uterine Cervix. Mod Pathol 13, 261–274 (2000).