Testis & paratestis

• Cystic proliferation of trophoblasts in postchemotherapy resections from patients with metastatic, nonseminomatous germ cell tumors of the testis
• Not aggressive, with behavior that is similar to postchemotherapy residual teratoma

• Histologic examination of involved tissue

• Requires no further treatment, however, these patients should be carefully monitored on follow up

Contributed by Vikas Mehta, M.D.

• Choriocarcinoma:
  • Distinctly biphasic, hemorrhagic and pleomorphic; displays brisk mitotic activity
  • βhCG levels are expected to be highly elevated
• Teratoma:
  • Demonstrates varying degrees of atypia
  • Any type of tissue may be present, such as gastrointestinal glands, respiratory epithelium, cartilage, squamous epithelium with keratinization, primitive undifferentiated spindle cells or neuroepithelium
• Somatic malignancy, such as squamous cell carcinoma:
  • Hypercellular variants with foci of solid areas can mimic CTT

Which of the following is a feature consistent with cystic trophoblastic tumor?

1. Biphasic pattern of admixed cytotrophoblasts and syncytiotrophoblasts
2. Infiltrative growth pattern
3. Normal to mildly elevated serum levels of βhCG
4. Variable SALL4 expression in mononuclear cells

C. Normal to mildly elevated serum levels of βhCG is consistent with cystic trophoblastic tumors. Other features are characteristic of choriocarcinoma in which βhCG levels are expected to be highly elevated. Answer A is incorrect because choriocarcinoma is biphasic, hemorrhagic and pleomorphic and it displays brisk mitotic activity. Answer B is incorrect because choriocarcinoma exhibits an infiltrative and destructive pattern. Answer D is incorrect because SALL4 positivity is seen in cytotrophoblasts in choriocarcinoma.

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Reference: Cystic trophoblastic tumor

Which of the following statements is true for cystic trophoblastic tumors (CTTs)?

1. CTTs after chemotherapy show a high frequency of progressive disease and warrant additional chemotherapy
2. CTTs are identified exclusively in the setting of postchemotherapy retroperitoneal lymph node dissections of patients with testicular germ cell tumors
3. CTTs lack keratohyaline granules and central keratin and often have intracytoplasmic lacunae
4. CTTs show goblet cells, ciliated cells and other specialized epithelial types

C. CTTs lack keratohyaline granules and central keratin and often have intracytoplasmic lacunae. Answer A is incorrect because the prognosis of CTT is similar to teratoma and requires no further treatment but a close follow up. Answer B is incorrect because CTT was first described in retroperitoneal lymph node dissections after chemotherapy; however, it is now known that these tumors can occur as part of primary testicular mixed germ cell tumors and they are occasionally seen in visceral and nonregional lymph node germ cell tumor metastases. Less commonly, these tumors have been described in germ cell tumor patients without chemotherapy. Answer D is incorrect because cysts are lined by squamoid appearing cells with smudged irregular nuclei, abundant eosinophilic cytoplasm with intracytoplasmic lacunae and associated fibrinoid material.

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Reference: Cystic trophoblastic tumor