Gestational trophoblastic diseases (GTDs) represent a unique group of lesions with an abnormal proliferation of trophoblasts. GTD can be divided into molar lesions and nonmolar lesions. Partial and complete hydatidiform moles and invasive moles are under molar lesions, whereas non‑molar lesions include choriocarcinomas and lesions that are derived from intermediate trophoblasts (ITs). These IT can be from the implantation site (exaggerated placental site [EPS] and placental site trophoblastic tumor) or from the chorionic type (placental site nodule and epithelioid trophoblastic tumor). EPS is a relatively uncommon form of GTD. It is a challenging condition for clinicians to diagnose because of the limited number of reported cases. From 1990 to April 2022, there were only 25 case reports published internationally, and this is the first local case report. Implantation site ITs (ISITs) are difficult to distinguish histologically. Immunohistochemical staining such as Ki‑67 can improve diagnostic accuracy by differentiating ISIT. Ki 67 will show staining of <1% in EPS. This is the case of a 25‑year‑old patient, G6P5 (5005), who experienced vaginal bleeding associated with pelvic and hypogastric pain after 13 weeks of missed menses. She was diagnosed with a molar pregnancy and underwent an emergency total abdominal hysterectomy with bilateral salpingectomy due to severe uterine bleeding. Histopathologic studies in this case showed diffuse and infiltrative growth of atypical monomorphic ITs arranged in sheets and cords, infiltrating and separating myometrial fibers. The uterine blood vessel wall was replaced with fibrinoid deposition, with areas of hemorrhages and necrosis. There were also chorionic villi. The histopathological findings revealed GTD arising from ITs, specifically EPS. This article describes the clinical presentation, diagnostic procedure, and management, together with histopathological observations and a review of related literature, of this rare GTD.

Marie Mae Gonzales Pantolla-Laxamana is the faculty of medicine at Las Piñas General Hospital and Satellite Trauma Center, Philippines