Primary adenocarcinoma of the renal pelvis: A case report

Primary adenocarcinoma of the renal pelvis is a rare malignant tumor, with approximately 100 cases reported in the English literature. This malignancy is characterized by high-grade aggressiveness, diagnostic challenges at initial presentation, and advanced disease at diagnosis, leading to poor overall prognosis. Historically, treatment has focused on surgical resection combined with chemotherapy, but documented cases remain scarce. The emergence of immune checkpoint inhibitors (ICIs) necessitates the exploration of novel therapeutic combinations to improve survival outcomes. We present a case of primary renal pelvic adenocarcinoma managed with a multimodal approach integrating radical surgery, adjuvant chemotherapy, and concurrent ICI therapy, resulting in prolonged survival.

A 61-year-old male presented with a 3-month history of recurrent left flank and abdominal pain. He reported no hematuria or weight loss but expressed concern about worsening pain unresponsive to prior interventions. A left nephrostomy performed at an outside hospital revealed a renal pelvic mass, prompting a referral for further evaluation.

Previous left nephrostomy and drainage at a local hospital revealed a renal pelvic mass, with a biopsy confirming adenocarcinoma. Contrast-enhanced computed tomography demonstrated abnormal thickening of the left renal pelvis, calyces, and upper-middle ureter, retroperitoneal lymphadenopathy, postnephrostomy changes, and bilateral renal calculi. Serum carbohydrate antigen 19-9 (CA19-9) was elevated to 431.793 U/mL.

Laparoscopic radical left nephroureterectomy with partial cystectomy was performed on January 12, 2023, revealing a thickened left ureter and retroperitoneal lymphadenopathy. Pathology confirmed an 8 cm moderately differentiated adenocarcinoma infiltrating renal/ureteral/bladder tissues. Immunohistochemistry: CK(+)/CK7(+)/CEA(+), Ki-67 20% to 30%. Intraoperative pirarubicin instillation was administered.

Postoperative stage IV disease received 2 cycles of adjuvant docetaxel. Disease progression (April 2023) prompted gemcitabine + tislelizumab (6 cycles), achieving a partial response (lymph node regression; CA19-9: 431.8→22.4 U/mL). Acute kidney injury (August 2023) necessitated tislelizumab monotherapy (3 cycles). Lymph node recurrence (January 2024) led to gemcitabine-tislelizumab rechallenge (2 cycles), followed by tislelizumab-pemetrexed (3 cycles) for stable disease. Bilateral lung metastases emerged post-treatment discontinuation (January 2025), treated with toripalimab-lenvatinib (1 cycle). The final follow-up (March 2025) documented 28-month survival (Eastern Cooperative Oncology Group 1).

This case underscores the imperative for multimodal integration (surgery, chemotherapy, and ICIs) to optimize survival in advanced renal pelvic adenocarcinoma while highlighting the necessity of dynamic therapeutic adaptation-including regimen rechallenge and tyrosine kinase inhibitor combinations-to address recurrence and resistance. Proactive toxicity management (e.g., dose de-escalation for renal injury) and rigorous biomarker-driven surveillance (serial CA19-9 tracking with 3-month imaging) emerge as critical strategies to balance efficacy and safety in this aggressive malignancy.