Placental site nodules and plaques: a clinicopathological and immunohistochemical study of 25 cases with ultrastructural findings

Placental site nodules or plaques (PSN-Ps) are nodular benign lesions of the intermediate trophoblast (IT) cells in the endometrium, endocervix, superficial myometrium or fallopian tube, occurring after a remote intrauterine pregnancy. We present a study of 25 cases of PSN-Ps. These lesions occurred in patients aged 18 to 44 years. Most were discovered incidentally in endometrial curettage specimens. The specimens were received as part of clinical investigations for menorrhagia, per vaginal bleeding or pelvic pain. None of the PSN-Ps was visible grossly. Microscopically, they were mostly multiple, well-circumscribed, oval or plaque-like cellular nodules. The IT cells typically had abundant vacuolated or eosinophilic cytoplasm. The nuclei were irregular, large, hyperchromatic, often degeneratelooking and either mononucleated, multinucleated or multiclefted. Hyalinisation surrounding individual or groups of IT cells, or located in the centre of the nodules, was a constant feature in all cases. The lesional ...