A case of placental site trophoblastic tumor complicating nephrotic syndrome in which hysteroscopic biopsy did not yield a definitive diagnosis

Abstract

Placental site trophoblastic tumor (PSTT) is the rarest subtype of gestational trophoblastic neoplasm. We present a case of PSTT complicating nephrotic syndrome. A 32-year-old woman experienced irregular menstrual bleeding and lower extremity edema 18 months after delivery. She was diagnosed with nephrotic syndrome and exaggerated placental site based on the hysteroscopic biopsy results. During follow-up, transvaginal color Doppler ultrasound showed an enlarged uterus filled with a hypervascular mass. Positron emission tomography-computed tomography showed diffuse accumulation in the entire uterus. The patient was diagnosed with PSTT only after total hysterectomy. Postoperatively, serum β-human chorionic gonadotropin decreased to within the normal range and her nephrotic syndrome resolved. She has remained without evidence of recurrence for 15 months. It is difficult to diagnose PSTT definitively. Most patients with PSTT are of reproductive age, therefore, to maintain fecundity, therapy development is expected.

Keywords: computed tomography; gestational trophoblastic neoplasia; placental site trophoblastic tumor; positron emission tomography.

Figure 1

(A) Before total hysterectomy, transvaginal color Doppler ultrasound revealed an enlarged uterus filled with a hypervascular mass in the endometrium and myometrium. (B) Before MTX therapy, CT and MRI showed an enlarged uterus, but the tumor was not found clearly in the uterus. (C) Before total hysterectomy, CT and MRI revealed an enlarged uterus filled with a hypervascular mass in the endometrium and myometrium, enlarged vessels in the myometrium, and enlarged gonadal vessels. After MTX treatment, repeat PET-CT showed uptake in the accumulation images, but there was a clear decrease in maximum standardized uptake value. (D) Before MTX treatment; (E) after MTX treatment. CT=computed tomography; MRI = magnetic resonance imaging; MTX = methotrexate; PET = positron emission tomography.

Figure 2

(A) Macroscopically, the disease spreads through the whole uterus. (B) Microscopically, the tumor cells consisted of intermediate trophoblasts arranged in sheets and cords throughout the smooth muscle fibers of the myometrium, with invasion of blood vessel walls in the myometrium, nuclear atypia, and a higher number of mitotic figures (4–10/10 high-power fields). Immunohistochemically, the tumor cells were positive for hPL and human chorionic gonadotropin (hCG). The Ki-67 labeling index was > 13%. HE = hematoxylin and eosin.