Seminoma pathophysiology

On gross pathology, seminoma is characterized by pale gray to yellow nodules that are uniform or slightly lobulated and often bulge from the cut surface.On microscopic pathology, seminoma is characterized by the cells with fried egg appearance with clear cytoplasm and central nucleus with prominent nucleolus, with interspersed lymphocytes and syncytiotrophoblasts. Approximately 24% of Stage I seminomas have lymphovascular invasion for stage I (Tx, N0, M0). Intertubular seminoma may not form a discrete mass and mimic a benign testis. Seminoma is demonstrated by positivity to tumor markers, such as OCT4, CD117, D2-40, and CD117.

On gross pathology, seminoma is characterized by pale gray to yellow nodules that are uniform or slightly lobulated and often bulge from the cut surface.^[1]

• 
  _{Gross specimen of testicle demonstrating a solid, white/tan mass.^[2]}

• On microscopic pathology, seminoma is characterized by:^[2]

• Cells with fried egg appearance – key feature

• Clear cytoplasm
• Central nucleus, with prominent nucleolus. Nucleus may have “corners”, i.e. it is not round.

• Lymphocytes – interspersed (common)
• Syncytiotrophoblasts, present in 10-20% of seminoma

• Large, irregular, vesicular nuclei
• Eosinophilic vacuolated cytoplasm (contains hCG)

• Florid granulomatous reaction

• Approximately 24% of Stage I seminomas have lymphovascular invasion for stage I (Tx, N0, M0).^[2]
• Intertubular seminoma may not form a discrete mass and mimic a benign testis.^[2]

• 
  _{Microscopic image of seminoma demonstrating fried egg-like cells (clear or eosinophilic cytoplasm, central nucleus) and lymphocytic infiltrate.^[2]}
• 
  _{Very high magnification micrograph of a seminoma with syncytiotrophoblasts on H&E stain. Syncytiotrophoblasts are seen in approximately 10-20% of seminomas. They may be associated with an elevated serum beta-hCG.^[2]}
• 
  _{Histopathological image of metastatic seminoma in the inguinal lymph node on hematoxylin & eosin stain.^[2]}

Seminoma is demonstrated by positivity to tumor markers, such as:^[3]

• OCT4
• CD117
• D2-40
• CD117

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