Germ cell neoplasia in situ


  • Gonocyte-like germ cells with abundant clear cytoplasm and large nuclei with coarse chromatin and expressing embryonic germ cell markers, located in the basilar aspect of the seminiferous tubules; considered to be the precursor of the majority of malignant testicular germ cell tumors. Also called testicular intratubular germ cell neoplasia, unclassified (ITGCNU), in the previous World Health Organization (WHO) classification.

Clinical features


  • Germ cell neoplasia in situ (GCNIS) is derived from primordial germ cells that fail to differentiate into spermatogonia.

  • The true incidence in the general population is difficult to obtain without invasive procedures.

  • The highest incidence was reported in a Danish population as 0.8%.

  • One of the most important risk factors is cryptorchidism, in which 2%–8% of patients will develop GCNIS.

  • The other major risk factor is the presence of a contralateral testicular germ cell tumor. In this group of patients, the risk of having contralateral GCNIS is 50-fold to 100-fold higher than that of the general population, which is reported to be 4.9%–5.7%.

  • All the other risk factors for developing testicular germ cell tumors are also risk factors for developing GCNIS, such as infertility, androgen insensitivity syndromes, mixed gonadal dysgenesis, and a history of extragonadal germ cell tumors.

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