Rationale:Collecting duct carcinoma (CDC) is a rare type of nonclear renal cell carcinoma, often presenting at an advanced stage of the disease, and standard treatment guidelines have not been established.Patient concerns:A 73-year-old man was admitted to our hospital with complaints of fever and lower right back pain.Diagnoses:Computed tomography revealed a poorly defined tumor of the right kidney without metastasis. The patient underwent right radical nephrectomy and was diagnosed with clinical stage T1bN0M0 renal cancer; the pathological findings showed collecting duct carcinoma.Interventions:After nephrectomy, multiple lung metastases were found in the following month, so first-line chemotherapy of gemcitabine (1000 mg/m2 on days 1 and 8, every 21 days) and cisplatin (70 mg/m2 on day 2, every 21 days) was administered. Due to disease progression, targeted therapy with axitinib (10 mg/body) and second-line chemotherapy of paclitaxel (200 mg/m2 on day 1, every 21 days) and carboplatin (area under the curve of 6 on day 1, every 21 days) were subsequently administered. However, the lung metastases progressed and new metastases spread to the right adrenal gland, liver, and lymph nodes. Based on the high expression of programmed death-ligand 1 in tumor cells, we treated the patient with the immune checkpoint inhibitor nivolumab.Outcomes:After 2 courses of treatment, he experienced a partial response and improved performance status, and thus was discharged from the hospital. To date, the patient is on his fifth course of treatment as an outpatient without disease progression.Lessons:The findings of our study suggest that nivolumab may be effective even if the patient has highly progressive CDC with a low PS, if PD-L1 is highly expressed in the tumor cells.

Abbreviations & Acronyms AC = adjuvant chemotherapy ACT = actinomycin AWD = alive with disease CDDP = cisplatin CPT-11 = irinotecan CT = computed tomography CTh = chemotherapy DOD = dead of disease DOXO = doxorubicin DR = distant recurrence DTX = docetaxel hydrate Dx = diagnosis ER = estrogen receptors GEM = gemcitabine IFO = ifosfamide LR = local recurrence MMC = mitomycin C MRI = magnetic resonance imaging n.r. = not reported NAC = neoadjuvant chemotherapy NCI CTCAE = National Cancer Institute Common Terminology Criteria for Adverse Events NED = no evidence of disease PgR = progesterone receptors PIRA = pirarubicin PR = partial response PSPUMP = proliferation of uncertain malignant potential PSS = prostate stromal sarcoma RCP = radical cystoprostatectomy RP = radical prostatectomy RT = radiotherapy SD = stable disease STUMP = stromal tumors of uncertain malignant potential VCR = vincristine Vp-16 = etoposide