Germ Cell Tumors (GCTs)
GCTs arise from the primitive germ cells of the gonad. They are most common in adolescents and young adults.
1. Key GCTs and Markers
| Tumor | Key Histology/Feature | Marker |
|---|---|---|
| Dysgerminoma | Large cells in lobules with fibrous septa (lymphocytic infiltration). | hCG, LDH |
| Yolk Sac | Schiller-Duval bodies (glomeruloid-like structures). | AFP |
| Choriocarcinoma | Cytotrophoblast & Syncytiotrophoblast (no villi). | hCG (very high) |
| Teratoma | Tissues from all 3 germ layers (ectoderm, mesoderm, endoderm). | Variable |
2. Exam Must-Knows
- Dysgerminoma: The most common malignant germ cell tumor in females; equivalent to male seminoma. Radiosensitive.
- Struma Ovarii: A specialized teratoma composed primarily of mature thyroid tissue; may cause hyperthyroidism.
- Choriocarcinoma: Very aggressive, early hematogenous spread to lungs (“cannonball metastases”). Note: No villi.
Pathology Board Hint: Focus on the markers for the boards. Yolk Sac = AFP. Choriocarcinoma = hCG. Dysgerminoma = hCG + LDH. If you see a pediatric patient with an ovarian mass and elevated AFP, it’s a Yolk Sac tumor until proven otherwise.