What is a seminoma and is it benign?

Seminoma: A Malignant Testicular Germ Cell Tumor

A seminoma is a malignant germ cell tumor of the testis that requires prompt diagnosis and treatment, as it is not benign. 1

Characteristics and Epidemiology

Seminoma is one of the most common testicular cancers with the following characteristics:

• Represents approximately 50% of all testicular germ cell tumors (TGCTs) 1
• Primarily affects Caucasian males aged 15-40 years, with a peak incidence in men aged 25-35 years 1, 2
• Tends to affect slightly older men compared to non-seminomatous germ cell tumors 2
• Usually presents as a painless testicular mass or swelling 3
• Has excellent prognosis with cure rates approaching 100% in stage I disease and exceeding 80% in metastatic cases 1

Diagnosis

The diagnostic approach for suspected seminoma includes:

1. Clinical examination: Identification of a painless solid testicular mass

2. Imaging:

   • High-frequency ultrasound (>10 MHz) is the first-line imaging modality 4, 3
   • Seminomas typically appear as homogeneously hypoechoic masses on ultrasound 3
   • MRI may help confirm intratesticular location in challenging cases 3
   • CT provides valuable information for staging, particularly regarding retroperitoneal lymph nodes 3

3. Laboratory tests:

   • Serum tumor markers before orchiectomy 1, 4:
     • Alpha-fetoprotein (AFP) - should be normal in pure seminoma
     • Beta-human chorionic gonadotropin (β-hCG) - may be elevated in some cases
     • Lactate dehydrogenase (LDH)

   Important caveat: Patients with elevated AFP should be managed as having non-seminoma, even if histology shows pure seminoma 1

4. Definitive diagnosis: Radical orchiectomy with histopathological examination 1

Management

The primary treatment for seminoma is radical orchiectomy, followed by stage-specific management:

1. Radical orchiectomy:

   • Performed through an inguinal incision 1
   • Scrotal violation must be strictly avoided as it increases risk of local recurrence 4
   • The tumor-bearing testis is resected with the spermatic cord at the level of the internal inguinal ring 1

2. Organ-preserving surgery may be considered in specific situations 1:

   • Synchronous bilateral testicular tumors
   • Metachronous contralateral testicular tumor
   • Tumor in a solitary testis or contralateral atrophic testis
   • Must be performed only in highly experienced centers

3. Post-orchiectomy management depends on stage:

   • Stage I: Options include surveillance, adjuvant radiotherapy, or single-agent carboplatin 2
   • Advanced stages: Platinum-based chemotherapy regimens 5

Prognosis and Follow-up

• Seminoma has an excellent prognosis, particularly when diagnosed early 1, 2
• Five-year survival rates approach 100% for stage I disease 1
• Regular follow-up is crucial to detect recurrence early 6
• Patients who miss follow-up appointments are at risk for metastatic disease 6

Important Distinctions

• Seminoma must be distinguished from benign testicular conditions such as segmental infarction, hematoma, infection, and epidermoid cysts 3
• Other malignant conditions that may mimic seminoma include non-seminomatous germ cell tumors, lymphoma, and metastases 3
• Spermatocytic tumor (formerly known as spermatocytic seminoma) is distinct from classic seminoma, affecting older patients and showing more indolent behavior 3

Common Pitfalls to Avoid

1. Misdiagnosing seminoma as benign: All solid testicular masses should be considered malignant until proven otherwise
2. Scrotal violation: Any scrotal approach for biopsy or surgery should be avoided 1, 4
3. Relying solely on tumor markers: Normal serum tumor markers do not exclude testicular cancer, as approximately 30-40% of patients have normal markers 4
4. Inadequate follow-up: Regular surveillance is essential, as demonstrated by cases where missed follow-up led to metastatic disease 6
5. Misinterpreting elevated AFP: Pure seminoma does not secrete AFP; patients with elevated AFP should be managed as having non-seminoma regardless of histology 1