A 29-year-old woman, 14 months after evacuation of a molar pregnancy, has persistent amenorrhea and mild uterine enlargement. Serum beta-hCG is only mildly elevated at 900 mIU/mL despite a bulky uterus. Hysterectomy specimen shows a hemorrhagic mass composed of sheets of intermediate trophoblast invading myometrium with individual myocyte entrapment, extensive vascular invasion, and scanty necrosis. IHC shows strong human placental lactogen positivity. What is true regarding this tumor?

• A It is exquisitely sensitive to methotrexate chemotherapy
• B It secretes low levels of beta-hCG relative to tumor bulk and responds poorly to chemotherapy, so hysterectomy is often required ✓
• C It produces very high beta-hCG levels and lung metastases are present in most patients at diagnosis
• D It is a benign lesion that regresses spontaneously with expectant management

Explanation

This is placental site trophoblastic tumor, derived from intermediate trophoblast at the implantation site. Intermediate trophoblast produces human placental lactogen abundantly but beta-hCG poorly, so hCG is disproportionately low relative to disease burden, unlike choriocarcinoma where markedly elevated hCG and early hematogenous spread dominate. Because PSTT is relatively chemoresistant, hysterectomy is the mainstay for localized disease. Methotrexate sensitivity applies to low-risk gestational trophoblastic neoplasia, and spontaneous regression does not occur, excluding A, C, and D.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.