02180nas a2200229   4500008003900000245013400039210007000173260000800243300000600251490000700257520150900264100001901773700001301792700001401805700001101819700001601830700001401846700001701860700001301877700001501890856004501905       2023                          d00aMüllerian-Type Clear Cell Carcinoma of Donor Origin in a Male Patient with a Kidney Transplant: Ascertained by Molecular Testing0 aMüllerianType Clear Cell Carcinoma of Donor Origin in a Male Pat  cOct  a10 v303 aClear cell carcinomas of Müllerian origin have a strong female predominance and only extremely rarely will arise within the kidney, presumably due to ectopic Müllerian embryogenesis. Herein, we report a unique case of metastatic Müllerian type clear cell carcinoma in a 37-year-old patient who had previously received a transplanted kidney from his father at age 11 (due to severe bilateral vesicoureteral reflux) and remained on chronic immunosuppression. The tumor was highly aggressive and demonstrated somatic mutations in NF2 and SETD2. Imaging of the transplanted kidney did not reveal any clear evidence of malignancy. However, targeted multigene sequencing and short tandem repeat testing revealed that the cancer was of donor origin, presumably from ectopic Müllerian tissue transplanted to the patient along with the kidney graft. The tumor was resistant to first-line therapy with a triple combination of carboplatin plus paclitaxel plus bevacizumab, as well as to second-line immunotherapy with nivolumab plus ipilimumab after tapering down the patient's immunosuppression. Despite the tumor being genetically distinct from the host, the use of immune checkpoint therapy with nivolumab plus ipilimumab did not yield a response. This unique case showcases the value of molecular testing in determining the tumor origin in patients with solid organ transplants who present with cancers of unknown primary. This can prompt the potential investigation of other recipients from the same donor.1 aIorgulescu, JB1 aShaw, LK1 aRashid, A1 aRao, P1 aMandayam, S1 aPatel, KP1 aSchmeler, KM1 aYang, RK1 aMsaouel, P  uhttp://613633.bywedr.asia/reference/5104