Extragonadal mediastinal seminoma

Case contributed by Sherif Mohsen


Chest pain.

Patient Data

Age: 30 years
Gender: Male

Huge anterior mediastinal (prevascular) mass lesion is seen measuring about 7.5 x 15.5 x 12.5 cm.

It shows a lobular outline with multiple diffuse areas of internal cystic breakdown and foci of calcification. The mass is seen encasing and compressing the left and right innominate veins, as well as superior vena cava. It abuts the main and left pulmonary arteries, markedly displacing the aortic arch and trachea to the right. It compresses the left lower bronchus with subsequent left lower lobar collapse.

Small left pleural effusion. 

Unremarkable other scanned areas of the abdomen and pelvis. 


Nuclear medicine

Huge metabolically active anterior mediastinal (prevascular) mass lesion is seen with max.SUV ~16.1

Case Discussion

The case was pathologically proven as extragonadal seminoma.

  • 90% of seminomas occur in men aged 20-40 years.
  • symptoms/signs:
    • chest pain, dyspnea, cough
    • fever, weakness, weight loss
  • prognosis: 90% 5-year survival without metastases
  • top differential diagnoses:
    • thymoma (invasive) 
    • lymphoma
    • teratoma
  • best diagnostic clue: large prevascular mediastinal mass with calcifications in a young man

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