Histopathological examination of a uterine specimen from a woman with gestational trophoblastic neoplasia shows sheets of atypical cytotrophoblast and syncytiotrophoblast with extensive haemorrhage and necrosis. Which additional finding would establish invasive mole rather than choriocarcinoma as the diagnosis?

• A Absence of vascular invasion
• B Marked nuclear pleomorphism of the trophoblastic cells
• C Presence of identifiable chorionic villi within the myometrium ✓
• D Immunoreactivity for human placental lactogen

Explanation

The defining difference is architectural: invasive mole retains hydropic chorionic villi that invade the myometrium, whereas choriocarcinoma consists purely of malignant cytotrophoblast and syncytiotrophoblast with no villi whatsoever. Both tumours show pleomorphism, haemorrhage, necrosis and vascular invasion, so those features cannot discriminate. Human placental lactogen staining marks intermediate trophoblast and points toward a placental site tumour rather than either entity, making option D incorrect for this distinction.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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