We report for the first time a case of 2.5cm polypoid cervical endometriosis with a superficial growth pattern in a 48-year-old patient with past tubal ligation. The lesion showed metaplastic changes (clear cell, eosinophilic, micropapillary) and a prominent Arias Stella reaction in the absence of concomitant pregnancy but presumably related to phytoestrogenic treatment. The eutopic endometrium, however, had a usual proliferative appearance, implying that it showed a different response from the endometriotic tissues, suggesting the possibility of a metaplastic origin for the endocervical polypoid endometriosis. The unusual histology of the lesion led to an erroneous diagnosis of papillary serous carcinoma in the biopsy. This was subsequently excluded on finding endometrial-type stroma surrounding glands, and was confirmed immunohistochemically by a low Ki-67 index and negativity for p53. © 2010 International Society of Gynecological Pathologists.