Sonographic, Hysteroscopic, and Histopathological Findings of a Placental Site Nodule

A 40-year-old woman, gravida 3 para 1, presented for an evaluation of secondary infertility. Transvaginal sonography of the pelvis revealed an endometrial polyp-like lesion (Fig. 1A), which was confirmed with saline infusion sonography (Fig. 1B). The lesion was resected hysteroscopically (Fig. 1C). Histopathology showed multiple fragments of endometrial tissue with extravillous trophoblast and deposition of fibrinoid (Fig. 2A). Immunohistochemical staining for Ki-67, a proliferation marker, showed minimal nuclear positivity in the nodules, indicative of a low proliferative rate (Fig. 2B). The histology and immunohistochemistry was indicative of a placental site nodule (PSN). The patient underwent ovulation induction after surgery, which resulted in a biochemical pregnancy. Fig. 2(A) Histopathology with hematoxylin and eosin staining (100×) showing a fragment of proliferative endometrium containing a PSN. The lesion is well circumscribed and consists of pleomorphic extravillous trophoblast with hyperchromatic nuclei, embedded in fibrinoid. (B) Immunohistochemical stain for Ki67 (100×). The lower part of the figure shows proliferative endometrium with numerous nuclei staining with Ki67 (an expected finding), in contrast to the placental site nodule in the upper part of the figure, which shows only a few cells staining positively, consistent with a low proliferation index. View Large Image Figure Viewer Download Hi-res image