Clinical characteristics and outcomes of placental site trophoblastic tumor: experience of single institution in Korea

Abstract

Objective: Placental site trophoblastic tumor (PSTT) is the rarest form of gestational trophoblastic disease (GTD) and the optimum management is still controversial. In this study, we analyzed the clinical features, treatment, and outcomes of 6 consecutive patients with PSTT treated in our institution.

Methods: The electronic medical record database of Samsung Medical Center was screened to identify patients with PSTT from 1994 to 2017. Medical records for the details of each patient's clinical features and treatment were extracted and reviewed. This study was approved Institutional Review Board of our hospital.

Results: A total of 418 cases of GTD, 6 (1.4%) patients with PSTT were identified. The median age of the patients was 31 years. The antecedent pregnancy was term in all 5 cases with available antecedent pregnancy information and the median interval from pregnancy to diagnosis of PSTT was 8 months. The median titer of serum beta human chorionic gonadotropin (β-hCG) at diagnosis was 190.9 mIU/mL. Five (83.3%) patients presented with irregular vaginal bleeding and one (16.7%) had amenorrhea. All patients had disease confined to the uterus without metastasis at diagnosis and were successfully treated by hysterectomy alone. All of them were alive without disease during the follow-up period.

Conclusion: In this study, we observed low level serum β-hCG titer and irregular vaginal bleeding with varying interval after antecedent term pregnancy were most common presenting features of PSTT. In addition, we demonstrated hysterectomy alone was successful for the treatment of stage I disease of PSTT.

Keywords: Gestational trophoblastic disease; Placental site trophoblastic tumor; Prognosis.

Fig. 1. Image findings of case 6. (A) Transvaginal ultrasonography showed a multicystic mass measuring 7.8×5.1 cm in the posterior uterine wall with abundant blood flow, suspected gestational trophoblastic neoplasia (GTN). (B) Abdomen-pelvis computed tomography. (C) Pelvis magnetic resonance imaging showed about 7.2 cm sized mass with internal vascular structure in uterus. (D) Positron emission tomography-computed tomography.

Fig. 2. (A) Macroscopic features of placental site trophoblastic tumor (PSTT): about 6.5×4.2 cm sized irregular mass with infiltration of full depth of myometrium. (B) The PSTT had monomorphic intermediate trophoblastic cells extensively infiltrating the myometrium. (C) The tumor cells are large, mononucleate placental site intermediate trophoblast with scattered multinucleated cells. The cells have abundant eosinophilic cytoplasm and marked nuclear pleomorphism with large convoluted nuclei (hematoxylin and eosin staining, original magnification ×50, ×50).

Fig. 3. Immunohistochemical findings of case 6. (A) Tumor cells were positive for human placental lactogen (hPL). (B) Tumor cells were focally positive for human chorionic gonadotropin (hCG). (C) About 20% of the tumor cells were positive for Ki-67. (D) Tumor cells were strongly positive for cytokeratin 7 (CK 7).