PA28.1 | Testicular Tumors — Summary & Reflection

REFLECT

Before moving to the summary, take 3–4 minutes to consolidate:

1. Can you sketch the classification tree of testicular tumors from memory — separating GCTs (seminoma vs. NSGCTs), sex cord-stromal, and lymphoma, with age groups?

1. For each GCT subtype, can you identify: (a) its signature histological feature, (b) its marker pattern (AFP/β-hCG), and (c) its key differentiating behaviour?

1. Why is an elevated AFP in a 'pure seminoma' patient a clinical alarm that should change management?

1. A 25-year-old presents with a 1 cm testicular mass and massive bilateral pulmonary nodules. Which GCT subtype should top your differential, and why does it metastasize hematogenously so early?

1. Why is radical inguinal orchiectomy (rather than scrotal) the mandated surgical approach?

If any of these questions expose a gap, re-read the relevant section before proceeding to assessment.

KEY TAKEAWAYS

Testicular Tumors — Core Framework

Classification:
- 95% are germ cell tumors (GCTs): Seminoma (~55%), NSGCTs (embryonal carcinoma, YST, choriocarcinoma, teratoma, mixed)
- 5% sex cord-stromal (Leydig, Sertoli) and lymphoma (most common in >60 yr men)

Pathogenesis:
- GCTs arise from GCNIS (precursor, OCT3/4+, PLAP+, intratubular)
- i(12p) = hallmark genomic alteration, present in ~80% of GCTs
- Spermatocytic tumor = exception: no GCNIS, no i(12p), benign

Morphology highlights:
- Seminoma: uniform cells, clear cytoplasm, lymphocytic septa, ± STGCs, NO hemorrhage
- Embryonal carcinoma: pleomorphic, hemorrhage/necrosis, pseudoglands
- YST: Schiller-Duval bodies, AFP+, most common in infants
- Choriocarcinoma: biphasic (cytotrophoblast + STGC), marked hemorrhage, early hematogenous spread
- Teratoma: tri-germ-layer elements; adult teratoma is NOT benign
- Leydig cell tumor: Reinke crystalloids, golden-brown, testosterone/estrogen excess

Marker rules (exam-critical):
- AFP elevated → YST, embryonal CA, or mixed GCT with those components
- AFP in pure seminoma = ALWAYS zero (elevated AFP forces reclassification to NSGCT)
- β-hCG markedly elevated → choriocarcinoma (early, even with tiny primary)
- β-hCG mildly elevated → seminoma with STGCs (≤ ~1000 IU/L)
- LDH → bulk/prognosis marker, non-specific

Spread:
- Primary route: lymphatic → para-aortic nodes (NOT inguinal)
- Choriocarcinoma exception: hematogenous first → lungs, liver, brain

Treatment:
- Seminoma: radiosensitive; Stage I = orchiectomy ± carboplatin/RT; advanced = BEP
- NSGCT: chemo (BEP); residual post-chemo masses resected (growing teratoma syndrome)
- All: radical INGUINAL orchiectomy (never scrotal)