Background <p>The concomitant presentation of upper urinary tract calculi and renal pelvis urothelial carcinoma is exceptionally rare in clinical practice. Parenchymal-invasive renal pelvis carcinoma often exhibits atypical imaging features, further complicating diagnosis. As both conditions share haematuria as a cardinal symptom, this overlap frequently leads to the misdiagnosis of one entity for the other.</p> Case presentation <p>We reported the symptoms and diagnosis of two cases of upper urinary tract stones with renal pelvis cancer that detected between May 2023 and December 2024. Two patients were newly diagnosed with upper urinary tract calculi for the first time. Lumbar pain was the primary symptom in both patients. Preoperative abdominal computed tomography (CT) showed only localized low-density soft tissue mass of the renal parenchyma (Tis or T1 stage), which was interpreted as focal inflammatory changes in the renal cortex due to combined renal pelvis infection, hydronephrosis, and nephrolithiasis. An absence of metastases was detected on CTU. Both patients subsequently underwent radical tumor surgery, and postoperative pathology confirmed high-grade invasive urothelial carcinoma in both patients.</p> Conclusion <p>Atypical imaging findings of upper urinary tract stones with renal pelvic cancer is often overlooked or misdiagnosed as infectious diseases. Abdominal CT may fail to detect small renal pelvic tumors. Renal pelvic cancer should be suspected in patients with papillary tumors observed during RIRS. Evaluation of the renal pelvic mucosa should include local biopsy, CTU, and urinary exfoliative cytology. Radical surgery is indicated for such cases.</p>