Sal-Like Protein 4-Negative Gestational Trophoblastic Neoplasia

Abstract

Gestational trophoblastic neoplasia (GTN) is a group of pregnancy-related malignancies caused by trophoblast cells, including invasive mole, choriocarcinoma, placental site trophoblastic tumor (PSTT), and epithelioid trophoblastic tumor (ETT). The diagnosis of GTN is often made by monitoring the serum level of human chorionic gonadotropin (hCG) with histological confirmation. Distinguishing between these entities is important for determining the appropriate treatment, but the differential diagnosis is not always straightforward. We report a case of GTN in a 35-year-old woman who had massive vaginal bleeding and persistently elevated hCG after intrauterine curettage for hydatidiform mole. She underwent total abdominal hysterectomy, and the histopathological examination revealed a biphasic proliferation of prominently atypical syncytiotrophoblast cells. The tumor had a high mitotic count, and the Ki-67 index was 50-90%. Immunohistochemical staining for atypical trophoblast cells showed weak diffusely in most but strong positive in partial for hCG, positive for human placental lactogen (hPL), negative for p63, and negative for Sal-like protein 4 (SALL4). Immunohistochemical results rather likely suggested PSTT; however, a high Ki-67 index, and hematoxylin and eosin stain (H&E) findings tended to be indicative of choriocarcinoma. She has been on a good course without recurrence for more than 3 years after surgical treatment. SALL4 has been reported to be a reliable immunohistochemical marker which is expressed in 100% of choriocarcinoma but not in PSTT or ETT. Our search of the literature did not reveal any SALL4-negative choriocarcinoma. We report a case of SALL4-negative GTN that could not be categorized as either choriocarcinoma or PSTT with a review of the literature. This rare case is valuable and may be helpful in the diagnosis of GTN in the future.

J Clin Gynecol Obstet. 2023;12(3):117-122
doi: https://doi.org/10.14740/jcgo922