Uterine cervical mesonephric hyperplasia with focal cystic change masquerading clinicopathologically as lobular endocervical glandular hyperplasia to malignancy

Abstract Introduction Although uterine cervical mesonephric hyperplasia (MH) arising from mesonephric remnants is a well-known but uncommon entity, it might pose a clinicopathological diagnostic challenge to distinguish from lobular endocervical glandular hyperplasia (LEGH) or adenocarcinoma, if MH rarely presents as a lobular and/or cystic mass with expansion of the cervical wall. However, few papers have described the detailed clinicopathological characteristics of MH compared to those benign to malignant lesions. Case presentation An early forties Japanese female presented with a history of increased vaginal watery discharge. Multiple cystic lesions measuring less than 3 mm in diameter generated a high signal intensity on T2-weighted MRI, in the bilateral aspects of the variably enlarged uterine cervix. A gross examination of a hysterectomy specimen revealed bilateral small multicystic lesions, filled partly with secreted fluids, measuring approximately 25 × 7 × 5 mm, respectively, located in the superficial to relatively deep cervical wall. A microscopic examination showed that these lesions predominantly consisted of a lobular proliferation of small to medium-sized tubules and cysts containing occasionally periodic acid-Schiff-positive eosinophilic/pink secreted materials, lined by bland-looking cuboidal to flattened epithelium. Immunohistochemically, these lining cells were specifically positive for CD10 in a characteristic luminal staining pattern, whereas negative for MUC6, and had a low MIB-1 labeling index. We ultimately made a diagnosis of cervical MH, lobular type, with focal cystic change. Conclusion We should be aware that, since gynecologists/pathologists might misinterpret MH as LEGH to malignancy, including the malignant counterpart of MH, a wide panel of immunohistochemical antibodies can be helpful supplemental tools.