Adenoma malignum (AM) of the cervix is a rare disease and it is difficult to diagnose due to the deceptively benign appearance of the tumor cells. These lesions have mucin-rich cystic lesions and are usually situated deep in the cervix. Since AM is very rare, standard screening tests, diagnostic tools and treatments have not yet been established. Radiologically, it mimics multiple nabothian cysts as a benign-looking tumor. Histologically, AM is a well-differentiated adenocarcinoma and could be misdiagnosed as a benign lesion. These findings make a preoperative diagnosis of AM difficult and can result in surgery being performed based on a misdiagnosis. We report here on four cases of pathologically confirmed AM.