Seminoma vs NSGCT:
- Seminoma tends to stay organ confined for longer – NSGCT more likely to present advanced
- Seminoma tends to spread to nodes only more often than NSGCT which is more likely than seminoma to have haematogenous spread
- Overall NSGCT more aggressive
Extra-gonadal germ cell tumours:
- Approx 5 %, mostly in midline locations retroperitoneum and mediastinum
- ? error in migration of germ cells during development
- Primary mediastinal NSGCTs are less sensitive to chemo – 5 year survival around 45 %
- Primary mediastinal seminoma similar prognosis to testicular seminoma
- Primary retroperitoneal GCTs are biologically indistinct from testicular GCTs with same prognosis
Classic seminoma
- Most common type
- Most common 30s and 40s
- Clear cytoplasm (“fried egg”)
- About 15 % have syncitiotrophoblasts which produce b-HCG (therefore 15 % seminomas will have raised b-HCG)
- Arises from GCNIS and may be a precursor to other NSGCT subtypes
- Anaplastic seminoma was a previously described subtype but had no clinical relevance so is no longer described
- Exquisitely radiosensitive
- Tends to be more homogenous and hypoechoic on ultrasound, cf. NSGCT more heterogenous
Spermatocytic tumour (formerly spermatocytic seminoma)
- Rare, tending to be in older men
- Metastasis is very rare – tends to be cured with orchidectomy alone
- Does not arise from GCNIS
Embryonal carcinoma
- Aggressive with high rates metastasis
- Occasional syncitiotrophoblasts and b-HCG production
- Most undifferentiated cell type of NSGCT – and can differentiate to other types including teratoma, within the primary or mets
- Can be smaller tumours but often more invasive
Choriocarcinoma
- Rare, aggressive, and haematogenous metastasis is common
- Typically produce very high levels of b-HCG (which can rarely cause other endocrinological disturbances)
- Widespread metastasis to lungs and other unusual sites not uncommon
Yolk sac tumours
- Pure yolk sac tumours are rare in adults, usually being mixed with other NSGCT
- More common in pre-pubertal kids and mediastinal GCT
- Roughly half have characteristic Schiller-Duval bodies
- Almost always produce AFP, only rarely produce b-HCG
Teratomas
- Contain cells from at least 2 of endoderm, mesoderm or ectoderm, in varying states of differentiation
- Roughly translates to “monster tumour” in Greek
- Pure teratomas are uncommon, but reasonably common in mixed NSGCT
- Generally normal tumour markers (rarely produce AFP)
- Teratoma is resistant to chemotherapy – therefore often residual masses post chemo may have teratoma
- Teratomas can grow aggressively and become large, and can transform to somatic malignancies like rhabdomyosarcoma or adenocarcinoma (teratoma with malignant transformation) – usually at metastatic sites
Sex cord stromal tumours:
- 90 % benign ; 10 % malignant
- Histological criteria to help distinguish malignancy
- Tumour > 5 cm
- Necrosis
- Vascular invasion
- Nuclear atypia
- High mitotic index
- Increased MIB-1 expression
- Infiltrative margins
- DNA ploidy
- Most malignant cases have at least 2 of these features – but the presence of metastatic disease is the only reliable criteria to distinguish
Leydig cell tumours
- Most common sex cord stromal tumour
- May present with symptoms due to excess androgens being converted peripherally to oestrogen – gynaecomastia, impotence, decreased libido
- May contain histologic Reinke’s crystals
- Chemoresistant and radioresistant – therefore need RPLND if metastatic
Sertoli cell tumours
- Rare < 1 %
- Assoc with Peutz-Jeghers syndrome
- Frequently bilateral
- Often associated with gynaecomastia
- Diagnostic work up and treatment/surveillance similar to Leydig cell tumours
Gonadoblastoma
- Usually in cases of DSD / phenotypically females
- Can progress to malignant GCT
- Bilateral orchidectomy generally recommended (up to 40 % bilateral involvement)
Follow up for sex-cord stromal tumours:
- No clear guidelines or evidence
- Metastatic Leydig/Sertoli tumours = poorer prognosis cf. germ cell tumour
- ?CT follow up for a few years
- RPLND if nodal metastases, no current role for chemotherapy
- Consider endocrinological follow up as well
