Testicular Teratoma

Testicular teratoma is a germ cell tumour with tissues from two or more embryonic germ layers (ectoderm, mesoderm and endoderm). It may be mature, immature or contain somatic type malignancy.

Pure teratoma makes up about 3 to 7% of adult testicular germ cell tumours and about 50% of prepubertal tumours, but teratoma elements are found in about 50% of mixed germ cell tumours.

Prepubertal teratoma is benign, whereas adult teratoma has metastatic potential, even when mature on histology.

Pathophysiology. In prepubertal boys the tumour arises without germ cell neoplasia in situ, and carries no isochromosome 12p. In postpubertal men it arises from germ cell neoplasia in situ and carries isochromosome 12p, with metastases that may show any germ cell tumour type.

Teratoma is resistant to chemotherapy and radiotherapy. When metastases are treated with chemotherapy, the sensitive elements disappear and teratoma remains, so it is found in about 40% of residual masses.

Complications of untreated or residual teratoma include:

• Growing teratoma syndrome: enlarging masses during or after chemotherapy while markers are normal.
• Late relapse, and transformation to somatic type malignancy (sarcoma, adenocarcinoma, primitive neuroectodermal tumour).

Markers are normal or mildly raised. AFP and hCG are usually normal in pure teratoma.

A painless testicular mass, often firm and irregular, sometimes with cysts. Metastatic disease may cause compressive symptoms from large retroperitoneal masses. In children, a slowly growing painless mass.

• Scrotal ultrasound: a heterogeneous, multicystic mass with calcification, cartilage or bone, and fat.
• AFP, beta-hCG and lactate dehydrogenase before orchidectomy, and repeated after it.
• CT of chest, abdomen and pelvis. MRI of the brain and bone imaging only for symptoms.
• Histology: mature, immature or somatic type malignant elements, with a search for other germ cell components, germ cell neoplasia in situ (present in adult teratoma), lymphovascular invasion and pT stage.
• Semen analysis and testosterone in adults. Creatinine clearance, audiometry and lung function if chemotherapy is planned.

Differential diagnosis.

• Epidermoid cyst
• Dermoid cyst
• Mixed germ cell tumour
• Yolk sac tumour
• Seminoma
• Testicular abscess or calcified lesion
• Leydig or Sertoli cell tumour

• Offer sperm banking to postpubertal males before surgery.
• Boys (prepubertal), mature teratoma with normal markers: testis sparing enucleation or partial orchidectomy, or radical orchidectomy when the testis cannot be preserved. No surveillance after complete resection beyond clinical and ultrasound review.
• Adults: radical inguinal orchidectomy with high ligation of the cord.
• Stage I: surveillance is common, or nerve sparing retroperitoneal lymph node dissection when lymphovascular invasion is present.
• Metastatic disease:
  • Chemotherapy has little effect on teratoma, but is given when markers are raised or other germ cell elements are present: BEP for 3 to 4 cycles.
  • BEP is repeated every 21 days: bleomycin 30 units intravenously on days 1, 8 and 15, etoposide 100 mg/m2 on days 1 to 5, and cisplatin 20 mg/m2 on days 1 to 5, with hydration (1 to 2 L of saline before and after, plus magnesium and potassium) and antiemetics for high emetic risk (ondansetron 8 mg, dexamethasone 12 mg and aprepitant 125 mg on day 1, then aprepitant 80 mg on days 2 and 3 with dexamethasone 8 mg on days 2 to 4).
  • Cisplatin needs creatinine clearance over 60 mL/min. Stop bleomycin for lung toxicity.
• Residual masses over 1 cm after chemotherapy with normal markers, or growing masses with normal markers: complete surgical resection of all disease sites. Resect early, since masses grow and can invade vessels, and treat somatic type malignancy by its own tumour type with platinum and other agents.
• Unresectable teratoma: no effective drug treatment exists, and specialist multidisciplinary review is needed.
• Late effects include cardiovascular disease, metabolic syndrome, hypogonadism, neuropathy, ototoxicity, bleomycin lung toxicity and second cancers. Offer sperm banking before treatment.

Monitoring. Markers and clinical review every 3 to 6 months for 2 years, then every 6 to 12 months to 5 years, with CT at intervals directed by risk. Late relapse can occur after 5 years, so yearly review continues in adults.

Referral and escalation. Refer to urology and to a specialist oncology centre with surgical expertise. Urgent referral for a growing mass, compressive symptoms or rising markers.