Noninvasive papillary urothelial carcinoma with pathological features in between low and high grades: A case report.

RATIONALE: Urinary bladder urothelial carcinoma is the most common malignant tumor in the urinary system, and noninvasive papillary urothelial carcinoma (NIPUC) comprises most bladder malignancies. NIPUC grading is important for therapeutic and clinical protocol selection. Here, we report a case of NIPUC with pathological features in between low (LG-NIPUC) and high (HG-NIPUC) grades NIPUC. PATIENT CONCERNS: A 72-year-old male, presenting with a 20-year history of hypertension and 5 months of hematuria. DIAGNOSES: Computed tomography examination revealed a tumor in the urinary bladder neck. Microscopic investigation revealed that most tumor tissue samples had a branching papillary architecture, with well-developed fibrous-vascular cores. Tumor cells were slightly crowded, with somewhat altered cell polarity and cell adhesion. Immunohistochemistry showed positive Ki67 staining, mostly in the basal layer, while p53 staining was rarely positive. These samples were diagnosed as LG-NIPUC. However, a few tumor tissue samples presented mildly fused papillary architectures without cell polarity or adhesion. Most nuclei stained intensely and were pleomorphic. All epithelial tissue layers were ki67 positive, and the p53 positive rate was higher than that in the LG samples. Therefore, these were classified as HG-NIPUC. INTERVENTIONS: The tumor was completely resected during lithotomy postural surgery. OUTCOMES: The patient is alive with a good recovery during 3 months after the surgery. LESSONS: We diagnosed this patient as having LG-NIPUC with local HG-NIPUC components. HG- and LG-HIPUC have different outcomes. This case is a new challenge for the pathological grading of NIPUC. An intermediate HIPUC grade might need to be added to the original NIPUC grading system.