The patient was then submitted to further left radical orchiectomy: 

Microscopy:  The entire testis has been submitted. The sections from the lesion adjacent to the rete testis show an irregular zone of interstitial fibrosis and which is accompanied by the proliferation of small blood vessels and a patchy stromal infiltrate of lymphocytes. The adjacent testicular parenchyma shows evidence of tubular atrophy with eosinophilic thickening of tubular basement membranes and focally prominent interstitial clusters of Leydig cells. Focally, the lining of the adjacent seminiferous tubules is partly replaced by a population of large atypical cells that have very prominent nucleoli and abundant clear cytoplasm. These cells show positive staining with PAS, as well as the immunomarkers ckit and PLAP, consistent with intratubular germ cell neoplasia, unclassified type. The vast majority of the testicular parenchyma is unremarkable. The macroscopically described spermatic cord nodule is epididymal tissue which is within normal limits.

Diagnosis: Left orchiectomy: Testicular parenchymal fibrous scar, consistent with burned out germ cell
tumor, with adjacent intratubular germ cell neoplasia (ITGCN). No invasive germ cell tumor identified.

Therefore, this case illustrates the spontaneous regression of a primary testicular seminoma that happened after the demonstration of retroperitoneal nodal metastases. This is known as a burned-out testicular seminoma.