title: Retroperitoneal teratoma with somatic malignant transformation: a papillary renal cell carcinoma in a testicular germ cell tumour metastasis following platinum-based chemotherapy.
abstract: BACKGROUND
  Malignant transformation describes the phenomenon in which a somatic component of a germ cell teratoma undergoes malignant differentiation. A variety of different types of sarcoma and carcinoma, all non-germ cell, have been described as a result of malignant transformation.
  
  
  METHODS
  A 33-year-old man presented with a left testicular mass and elevated tumour markers. Staging investigations revealed retroperitoneal lymphadenopathy with obstruction of the left ureter and distant metastases. Histopathology from the left radical orchiectomy showed a mixed germ cell tumour (Stage III, poor prognosis). The ureter was stented and four cycles of cisplatin, etoposide and bleomycin chemotherapy administered. After initial remission, the patient recurred four years later with a large retroperitoneal mass involving the renal vessels and the left ureter. Left retroperitoneal lymph node dissection with en-bloc resection of the left kidney was performed.Histopathology revealed a germ cell tumour metastasis consisting mainly of mature teratoma. Additionally, within the teratoma a papillary renal cell carcinoma was found. The diagnosis was supported by immunohistochemistry showing positivity for AMACR, CD10 and focal expression of RCC and CK7. There was no radiological or histo-pathological evidence of a primary renal cell cancer.
  
  
  CONCLUSIONS
  To the best of our knowledge, malignant transformation into a papillary renal cell carcinoma has not been reported in a testicular germ cell tumour metastasis following platinum-based chemotherapy. This histological diagnosis might have implications for potential future therapies. In the case of disease recurrence, renal cell cancer as origin of the recurrent tumour has to be excluded because renal cell carcinoma metastases would not respond well to the classical germ cell tumour chemotherapy regimens.
authors: Department of Urology, University Hospital Zürich, Zürich, Switzerland.
authors: Nina
authors: N
authors: Zeh
authors: Peter J
authors: PJ
authors: Wild
authors: Peter K
authors: PK
authors: Bode
authors: Glen
authors: G
authors: Kristiansen
authors: Holger
authors: H
authors: Moch
authors: Tullio
authors: T
authors: Sulser
authors: Thomas
authors: T
authors: Hermanns
mesh_terms: D000328:Adult; D018236:Carcinoma, Embryonal / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000556:secondary*; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D018240:Endodermal Sinus Tumor / Q000473:pathology; D006801:Humans; D008297:Male; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology*; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D012186:Retroperitoneal Neoplasms / Q000473:pathology / Q000556:secondary*; D018239:Seminoma / Q000473:pathology; D013724:Teratoma / Q000473:pathology / Q000556:secondary*; D013736:Testicular Neoplasms / Q000473:pathology*; D014516:Ureteral Neoplasms / Q000556:secondary
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