Florid endocervical glandular hyperplasia with intestinal and pyloric gland metaplasia: worrisome benign mimic of "adenoma malignum".

We describe three cases of florid endocervical glandular hyperplasia with intestinal and pyloric gland metaplasia, which can be a benign mimic of adenoma malignum. In two cases, adenoma malignum was seriously considered preoperatively because of watery vaginal discharge and the results of imaging studies. The three cases shared common histopathological features, i.e., (i) proliferating endocervical glands surrounded by clusters of smaller glands, resembling the pyloric glands of the stomach; (ii) occasional intestinal metaplasia; (iii) bland nuclear features; and (iv) predominantly PAS-positive neutral mucin in the glandular epithelium. In two cases, glands were densely and irregularly arranged in some areas. Immunohistochemistry disclosed that the intracytoplasmic mucin of the metaplastic epithelium was positive for M-GGMC-1 (HIK1083), which reacts with mucin of pyloric glands. Monoclonal CEA was negative in all cases. This pseudoneoplastic benign condition should be recognized by both gynecologists and pathologists, although it might be difficult to establish a definite diagnosis preoperatively even with deep cone biopsy.