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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Germ cell neoplasia in situ is the pre-cancer of testicular germ cell tumours: abnormal fetal-type germ cells sitting inside the seminiferous tubules, which will become seminoma or non-seminoma if left. It is found beside almost every testicular cancer and sometimes on its own in the other testis, where low-dose radiotherapy or surgery prevents a second cancer.
The pre-invasive lesion of postpubertal testicular germ cell tumours was recognised in the early 1970s and carried several names (carcinoma in situ, intratubular germ cell neoplasia unclassified, testicular intraepithelial neoplasia) until the 2016 WHO consensus classification united them as germ cell neoplasia in situ (Histopathology 2016; Moch 2016). The cells resemble seminoma cells, express OCT4, PLAP and KIT, lie along the tubular basement membrane in tubules without spermatogenesis, and are the origin of seminoma, embryonal carcinoma, yolk sac tumour, choriocarcinoma and postpubertal teratoma, but not of spermatocytic tumour or prepubertal tumours. Testicular biopsy is the only established way to diagnose it; serum microRNA-371a-3p, a marker of invasive germ cell tumours, was raised in 51.9 percent of 27 men with isolated GCNIS (J Cancer Res Clin Oncol 2017).
How it differs from its parent: it is not yet a cancer, is not staged and raises no conventional serum markers; its importance is the roughly one in two chance of progression to invasive tumour over five years quoted in the classification literature, which drives contralateral biopsy policies in some countries.
| Setting | Approach | Guideline |
|---|---|---|
| Isolated GCNIS in the remaining testis | Low-dose testicular radiotherapy, orchidectomy, or surveillance in men wanting children; the invasive tumour that follows is treated as seminoma or non-seminoma. | not mapped |