A 35-year-old woman is diagnosed with placental site trophoblastic tumour (PSTT). Which feature distinguishes PSTT from other gestational trophoblastic neoplasias and influences its treatment?

• A Markedly elevated β-hCG levels responding well to EMA-CO regimen
• B Propensity for haematogenous metastasis to lungs as first site
• C Arising exclusively from choriocarcinoma transformation
• D Predominant secretion of human placental lactogen (hPL) and relative resistance to standard chemotherapy regimens ✓

Explanation

Placental site trophoblastic tumour (PSTT) arises from intermediate trophoblast and is characterised by low/disproportionately low β-hCG relative to tumour burden, elevated human placental lactogen (hPL) as a more specific marker, and relative resistance to standard chemotherapy (EMA-CO). Hysterectomy is the treatment of choice for Stage I PSTT because of this chemoresistance. Unlike choriocarcinoma, EMA-CO has a lower efficacy; EP-EMA is preferred for metastatic disease.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.