Regressed Germ Cell Tumours
The phenomenon of regressed or "burned-out" germ cell tumour is well known but incompletely understood. The patient may present with widespread metastases even though the primary tumour has involuted. The pathogenesis of this phenomenon may be that the high metabolic rate of the tumour causes it to rapidly outgrow its blood supply. These tumours are clinically occult, with the testis being normal to small upon palpation.
The germ cell tumours undergo apparent spontaneous regression, resulting in complete or almost complete hyaline scarring. (This is variously referred to as spontaneous regression or “burnt-out” germ cell tumour).
In these cases, the testis typically is firm and white and on microscopic examination hyaline scarring is seen, sometimes with a minor component of associated viable neoplasia, such as seminoma, teratoma, or intratubular germ cell neoplasia - the latter may be a subtle clue to the diagnosis that what one is observing is something more specific than just an old hyalinized infarct on nonspecific atrophy.
Sometimes, the scar shows rather prominent vessels , hemosiderin-laden macrophages, chronic inflammatory cells and, particularly in cases that are presumptively “dead” embryonal carcinoma, intratubular calcification.
Although these regressed tumours may be sometimes clinically apparent as testicular abnormalities on palpation, they often only diagnosed on ultrasound.
Example: A patient is investigated after presenting with a retroperitoneal germ cell tumour, which is ultimately shown to be a metastasis from the regressed testicular primary.