Two or more histological types characterize more than 60% of testicular germ cell tumors (GCTs). Burned-out testicular tumor refers to partial or complete histological regression of the primary testicular lesions. The most frequent GCT type involved in this kind of histological regression is choriocarcinoma, followed by embryonal carcinoma. To our knowledge, there are no cases of the burned-out phenomenon in teratoma. We report a case of a 19-year-old man presenting to our institute with a right testicular lesion, evidence of mediastinal and abdominal lymph node metastasis, and high levels of GCT serum biomarkers. After orchiectomy, the histopathological examination showed a mixed GCT: mature teratoma, immature teratoma, and histological features of testicular cancer regression (burned-out phenomenon). The patient underwent first-line chemotherapy (BEP regimen) which resulted in a complete instrumental and biochemical response after 4 cycles. Teratoma is considered a less aggressive type of GCT. In this particular case, metastatic disease seems to result from non-germ cell components which underwent early spontaneous regression.

Background: Upper urinary tract urothelial carcinoma (UTUC) accounts for only about 5–10% of all urothelial cancers and is characterized by an aggressive and frequently rapidly fatal behavior. However, detailed knowledge of its molecular profile is still lacking. Materials and methods: We identified, by chart analysis, patients who underwent radical nephroureterectomy or diagnostic biopsy for UTUC between January 2015 and August 2020 at the Santa Maria Hospital of Terni, in Italy. Eligible patients were required to have also adequate clinical informations and follow-up details. The primary objective of the study was to evaluate DNA mismatch repair (MMR) proteins and Nectin-4 immunohistochemical expression in UTUC, looking also for an eventual correlation between these molecular features. The secondary objective was to investigate genomic instability in the case of a MMR protein loss. Expression of proteins was assessed by using immunohistochemistry and microsatellite instability (MSI) performed by next generation sequencing. Nectin-4 expression was reported using an intensity scoring system (score, 0–3+), instead the expression of DNA MMR proteins was indicated as present (no loss) or not present (loss). Results: Thirty four cases have been evaluated and 27 considered eligible for the study with their tumor samples analyzed. Nectin-4 was found to be expressed in 44% of cases and 18.5% of patients showed defective-MMR phenotype. We found a significant correlation between Nectin-4 expression and MSH2/MSH6 protein loss. Out of 7 patients with DNA MMR proteins loss or equivocal phenotype, 3 showed MSI. Conclusions: Our pilot study suggest a possible relationship between Nectin-4 and DNA MMR protein expression in UTUC and a clinically significant correlation between defective MMR phenotype and genomic instability. Because of the possible implications of these data for innovative treatment approaches, the need for further studies in this area is warranted.