Embryonal carcinoma

Clinical features

  • Peak incidence in the first decade
  • Pure forms are rare in children
  • More common in the testis than in the ovary
  • High serum human chorionic gonadotropin (HCG)
  • Less commonly elevated serum alpha-fetoprotein
  • Isosexual precocity: vaginal bleeding, amenorrhea, hirsutism

 

Fig 73 - Embryonal carcinoma – Cohesive group of pleomorphic tumor cells, with moderate amount of vacuolated cytoplasm. Necrosis in the background (Giemsa)
Fig 74 - Embryonal carcinoma – Ragged-edged cell clusters attached to branching capillaries. Cells are pleomorphic with coarse chromatin, prominent nucleoli and scant cytoplasm (H&E)

 

 

  • Cellular smears
  • Similar appearance to an adenocarcinoma:
    • Sheets, nests, glandular or papillary formations
    • Ragged-edged cell clusters
    • Large pleomorphic cells
    • Irregular nuclei
    • Coarse chromatin
    • Multiple prominent nucleoli
  • Sparse cytoplasm
  • Syncytiotrophoblast cells
  • Necrotic background

 

Immunocytochemistry (see Table 1)

  • Cytokeratin: positive
  • CD30: positive
  • Alpha-fetoprotein: positive (focal)
  • OCT4: positive
  • PLAP: positive (focal in syncytiotrophoblast cells)
  • EMA: Negative

 

Modern diagnostic techniques

  • Non-contributory

 

Differential diagnosis

  • Germinoma
    • Poorly cohesive cells
    • More monotonous population
    • Nuclei with clear chromatin and single nucleoli
    • Cytoplasmic glycogen vacuoles
    • Tigroid background
    • Lymphocytes
    • Placental alkaline phosphatase (PLAP): positive
    • CD117:positive
    • Cytokeratin: usually negative
    • EMA: negative
    • CD30: negative
  • Carcinoma
    • Rare in children
    • CD30: negative
  • Yolk sac tumour
    • Mucoid background
    • Less necrosis
    • Smaller cells
    • Intra and extra cytoplasmic hyaline globules
    • Dense basement membrane-like matrix associated with neoplastic cells
    • Alpha-fetoprotein: positive (intense)
    • CD30:negative

 

Table 1- Immunophenotype of germ cell tumours

 

Marker:

Seminoma

Yolk sac

tumour

Embryonal

carcinoma

Choriocarcinoma

AE1/AE3)

+/-

+

+

+

PLAP

+

+

+

+/-

AFP

-

+

+/-

-

Beta-HCG

- (except in giant cells)

-

-

+

S-100 protein

-

-

-

-

LCA

-

-

-

-

CD30

- (rarely +)

-

+

-

OCT4

+

-

+

-

 

AFP-alpha-fetoprotein; CK- cytokeratin; HCG- human chorionic gonadotropin; LCA- leukocyte common antigen; PLAP- placenta-like alkaline phosphatase; + positive; +/- positive or negative; - negative.

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