[Carcinoma in situ of the testis: clinical significance, diagnosis and therapy].

The term "carcinoma in situ (CIS) of the testis" is used to mean the presence of atypical neoplastic spermatogonia exhibiting distinct morphological and immunohistological characteristics that differentiate them from normal germ cells. The lesion is considered to be the uniform precursor cell of all germ cell tumors, and it can usually be detected many years before manifestation of the tumor by surgical biopsy and subsequent immunohistological staining for placental alkaline phosphatase (PIAP). This paper gives a review of the theoretical and clinical features of CIS. The description is based on data in the literature and on the authors' experience with two recently detected cases of CIS in the contralateral testis of patients with germ cell tumors. In view of the observation of intraepithelial spread inside the seminiferous tubules, the term "testicular intraepithelial neoplasia" (TIN) is suggested instead of carcinoma in situ.