Pathology for Urologists
Germ Cell Tumors (GCTs) General Features
- Tumors arising from germ cells, which may differentiate along gonadal lines (seminoma), extra-embryonic lines (yolk sac tumor or choriocarcinoma) or transform to totipotential cells (undifferentiated: embryonal carcinoma or differentiated: teratoma).
- Either pure (60%) or mixed (40%; >2 histology) tumors.
- Predisposing factors: cryptorchidism, testicular dysgenesis (e.g. testicular feminization and Klinefelter syndrome), prior or family history of GCT.
- Caucasian > African Americans.
- Secrete serum markers valuable in diagnosis and management:
- AFP (yolk sac tumor), HCG (choriocarcinoma) and LDH (not specific, level provides a tool to assess tumor burden).
- Painless testicular enlargement.
- Unilateral (only 2% bilateral).
- From clinical standpoint, most important distinction is between seminomas and non-seminomatous GCTs.
- Seminomas tend to remain localized for a longer time (70% stage 1) and metastasize via lymph nodes.
- Non-seminomatous GCTs metastasize earlier (60% stages II and III) via hematogenous spread.
- Seminoma is extremely radiosensitive whereas NSGCTs are relatively radioresistant.
- Seminoma occurs at age range 35-45 years; non-seminomatous GCT occurs in patients 10 years younger.
- GCTs in postpubertal men typically have 1 or > copies of chr 12p [most commonly i(12p)]; ~80% GCTs have at least 1 i(12p).
- Infantile teratoma often diploid, infantile yolk sac tumors often aneuploid and spermatocytic seminoma either diploid or aneuploidy.
- Immunohistochemistry: all GCTs are PLAP+ and SALL4+