Differential Diagnosis for Testicular Mass with High AFP

• Single most likely diagnosis
  • Non-seminomatous germ cell tumor (NSGCT), specifically yolk sac tumor: This is the most common testicular cancer in children and young adults, and it is known for producing high levels of alpha-fetoprotein (AFP).
• Other Likely diagnoses
  • Embryonal carcinoma: Another type of NSGCT that can produce elevated AFP levels, although not as consistently as yolk sac tumors.
  • Mixed germ cell tumor: Tumors that contain more than one type of germ cell component, including elements that can produce AFP.
• Do Not Miss diagnoses
  • Metastatic liver disease: Although rare, liver metastases from other primary cancers can cause elevated AFP levels and a testicular mass if the metastasis involves the testis.
  • Hepatocellular carcinoma with testicular metastasis: An uncommon scenario but one that would be critical to identify due to its implications for treatment and prognosis.
• Rare diagnoses
  • Gonadoblastoma: A rare tumor that can occur in dysgenetic gonads, sometimes producing AFP.
  • Sex cord-stromal tumors with heterologous elements: Extremely rare and would be an unusual cause of a testicular mass with high AFP, but could be considered in the differential diagnosis due to their potential to produce various tumor markers.