title: [Morphologic keys for the interpretation of the biology of testicular germ tumors].
abstract: OBJECTIVE
  To review the morphological aspects (classical and molecular) of the natural history of testicular germ cell tumors that have an impact on treatment.
  
  
  METHODS
  Data available in the literature published during the last 10 years and the experience of the Pathology Department of the Puigvert Foundation over the last 20 years were reviewed.
  
  
  CONCLUSIONS
  Intratubular germ cell tumor is the precursor lesion of testicular germ cell tumors. Its classification into seminoma and non seminomatous lesions continue to be useful for practical purposes. All available data indicate that an intermediate form of seminoma may exist. AFP production is more relevant in tumors of the vitelline sac, therefore determination of AFP in blood could indicate a tumor with this component. Furthermore, vitelline sac tumors may have morphological expressions (epithelial and mesenchymal) that could be the origin of many of the metastases that look like teratoma. One must be cautious in the biological evaluation of teratomas since nuclear atypias are common in the mature teratoma and cell density in the immature teratoma. Evidence of infiltrative growth is the only sign that indicates malignant teratoma. Retroperitoneal germ cell tumors are testicular metastases unless demonstrated otherwise, whereas mediastinal lesions are usually primary tumors.
authors.forename: F
authors.initials: F
authors.lastname: Algaba Arrea
mesh_terms: D018237:Germinoma / Q000473:pathology*; D006801:Humans; D008297:Male; D013736:Testicular Neoplasms / Q000473:pathology*