Case Report: Good responsiveness of metastatic sarcomatoid urothelial carcinoma with chondrosarcomatous differentiation to immune checkpoint inhibitor after radical surgery and adjuvant chemotherapy [version 1; peer review: 1 approved, 1 approved with reservations]

Background: Sarcomatoid urothelial carcinoma with chondrosarcomatous differentiation (SUCCD) in the ureter has a poor prognosis and is a rare histological variant of ureteral cancer. The majority of ureteral cancers are urothelial carcinomas. Clinical case: We present a case of well-controlled metastatic SUCCD treated with an immune checkpoint inhibitor after radical surgery and failed adjuvant chemotherapy. The patient was a 68-year-old male with previous cure history of cT1 staged esophageal squamous cell carcinoma referred to the urology department for a right hydronephroureterosis complicating an intraureteral enhancing mass. After ureteroscopic biopsy and intraureteral urine cytology, atypical pleomorphic cell nests and chondroid tissue consistent with sarcomatoid urothelial carcinoma were observed. The patient underwent a successful radical right nephroureterectomy with bladder cuffing. The final diagnosis was a pT3N0 sarcomatoid urothelial carcinoma (heterologous component: chondrosarcoma > 95%) located at the right distal ureter and right renal calyx with infiltration of the periureteric fat and renal parenchyma of the renal capsule. On the postoperative one-month follow-up computed tomography scan, multiple enlarged lymph nodes and metastatic lung nodules were detected. The initiated adjuvant three cycles of gemcitabine-carboplatin therapy was marked by disease progression; thus, second-line therapy with atezolizumab was used for treatment. After five cycles of atezolizumab, the tumors showed a partial response without any grade 3 complications. Conclusion: The recurrent metastatic SUCCD showed good response to the immune checkpoint inhibitor after unsuccessful therapy with radical surgery and first line chemotherapy despite the unfavorable outcome of the pathology.