A case of placental site nodule associated with cervical high-grade squamous intraepithelial lesion.

Introduction: A placental site nodule (PSN) is a remnant of intermediate trophoblast (extravillous trophoblast, EVT) from a previous pregnancy. Usually, this a benign lesion, which once removed, does not require any treatment and does not recur. Although this lesion is related to pregnancy, it may be detected many months or several years after the pregnancy from which it resulted. The lesion represents a degenerative process of EVT. Especially in tissue obtained from curettage, can microscopically mimic aggressive lesions of intermediate trophoblast, such as placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT), and in an unusual location can pose problems in differential diagnosis with other malignancies, as in the present cervical example.

Case Report: A 36-year-old female, gravida 2, para 1, with a history of early spontaneous abortion two years prior, was submitted to a cervical smear for abnormal uterine bleeding, which showed a cervical high squamous intraepithelial lesion (HSIL) with extension to the endocervical cells. Histologic examination of the endocervical curettage revealed haphazardly distributed fragments of tissue, showing extensive hyalinization and cells of different size with indistinct outlines, organized in small groups, singly, or in cords. Mitotic figures were absent. Immunohistochemical analysis revealed focal positivity to cytokeratin 8 (CK8) and placental alkaline phosphatase and negativity to high molecular weight cytokeratin. The Ki-67 index was low. As a result, the morphological and immunohistochemical findings led to the diagnosis of a PSN.

Conclusion: Diagnosis of a PSN in an unusual location also can pose problems in differential diagnosis with other malignancies, as in the present cervical example. In the present case, the cervical location and the association with HSIL might suggest an erroneous diagnosis of cervical invasive squamous carcinoma. Clinical and pathological data, with immunohistochemical study, are mandatory for a correct diagnosis of this lesion.