Seminoma
Epidemiology &
Etiology:
- Mean age
40y
- Rare <
10y, uncommon in adolescents
- Uncommon
> 60y
Gross features:
- large
bulky mass
- homogenous,
gray-white, lobulated cut surface
- usually
no necrosis or hemorrhage
Histologic features:
- sheets
of uniform cells
- delicate
septae of fibrous tissue making
poorly-demarcated lobules
- cells
are large, round/polyhedral, clear cytoplasm, distinct cell membrane
- varying
amounts of glycogen in cytoplasm
- sparse
lymphocytic infiltrate in septae (T-cells)
- granulomatous reaction in up to 50%
- large
central nucleus with 1 or 2 prominent nucleoli
- usually
associated with IGCN – consider sertoli cell tumour if no IGCN present
- 15%
contain syncytiotrophoblasts
Immunophenotype
& Special Stains:
|
Marker:
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Sensitivity:
|
Specificity:
|
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D2-40
|
|
ITGCN also
positive
|
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Keratin (neg or weak/focal)
|
|
All other GCTs
positive
|
|
placental
alkaline phosphatase (PLAP)
|
|
|
|
AFP (neg)
|
|
|
|
HCG (neg unless scattered syncitiotrophoblasts
are present)
|
|
|
|
c-kit (CD117)
|
|
|
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Oct 3/4
|
|
|
|
PAS + / PASD -
|
|
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Molecular features:
- Isochromosome 12p
- Other chromosome
12 anomalies
- hypertriploid
Other features:
- Beta-HCG
may be elevated (7-25%)
- More common
in patients with metastases
- Correlates
ith the presence of syncitiotrophoblastic
cells in the tumour
- AFP
not generally elevated
- If elevated,
may be indicative of unrecognized nonseminomatous
component in the testis or an occult metastasis