What is pure seminoma?

Pure Seminoma: Definition and Clinical Characteristics

Pure seminoma is a type of testicular germ cell tumor (TGCT) that accounts for approximately 50% of all testicular cancers, characterized by its distinct histological appearance and excellent prognosis with cure rates approaching 100% in early stages and exceeding 80% in metastatic disease. 1

Epidemiology and Incidence

• Affects primarily Caucasian males aged 15-40 years 1
• Incidence rate in Europe: 6.3 cases per 100,000 males per year 1
• Death rate: 0.38 cases per 100,000 males per year 1
• Bilateral tumors occur in 2-3% of cases during lifetime 1

Histopathological Features

• Pure seminoma is characterized by a uniform population of cells with clear cytoplasm and well-defined cell borders
• Must not have elevated alpha-fetoprotein (AFP) levels; if AFP is elevated, the tumor should be managed as nonseminoma 2
• May contain syncytiotrophoblasts which should be reported in pathology 1
• Pathognomonic genetic marker: increased copy numbers of iso-chromosome 12p 1

Diagnosis

• Definitive diagnosis requires histological examination of the testicular mass removed by radical inguinal orchiectomy 1, 2
• Testicular ultrasound (7.5 MHz transducer) is the initial imaging modality of choice 1
• Tumor markers must be measured before orchiectomy:
  • Beta-human chorionic gonadotropin (β-HCG) may be elevated
  • Alpha-fetoprotein (AFP) must be normal in pure seminoma
  • Lactate dehydrogenase (LDH) may be elevated 1

Staging and Risk Assessment

• Requires full blood count, renal function tests, electrolytes, and liver function tests 1
• CT scan of chest, abdomen, and pelvis is mandatory 1
• Bone scan indicated only in metastatic disease with bone symptoms or elevated alkaline phosphatase 1
• Risk stratification for stage I disease:
  • Low risk: tumor size <4 cm and absence of rete testis involvement (12% relapse risk)
  • High risk: tumor size >4 cm with rete testis invasion (32% relapse risk)
  • Intermediate: one risk factor present (15% relapse risk) 1

Treatment Approaches

• Initial treatment is radical inguinal orchiectomy for all patients 2
• Stage I disease management options:
  • Surveillance (preferred approach) with 99% disease-specific survival 2
  • Adjuvant carboplatin (AUC 7) for 1-2 cycles 2
  • Adjuvant radiotherapy to para-aortic strip (20 Gy in 10 fractions) 2
• Advanced disease (Stage II-III):
  • Stage IIA-B: dogleg radiotherapy or chemotherapy 2
  • Stage IIC-III: chemotherapy with 3-4 cycles of BEP (bleomycin, etoposide, cisplatin) 2

Clinical Pearls and Pitfalls

• Important pitfall: Minor elevations of AFP (≤16 ng/ml) in otherwise histologically pure seminoma may not necessarily indicate hidden yolk sac tumor components 3
• Sperm banking should be discussed before surgery or adjuvant therapy if fertility is a concern 2
• Long-term follow-up is essential as late relapses can occur, even after 25 years in rare cases 4
• Patients with pure seminoma have excellent prognosis, with multiple effective treatment options available 5

Pure seminoma represents one of the most curable solid tumors in oncology, with treatment decisions balancing efficacy against long-term toxicity concerns, particularly important given the young age of most affected patients.