To investigate the expression of POU2F3 in urinary tract small cell carcinoma (SmCC) and evaluate its diagnostic value.
Key Findings:
Five patients included: two females with bladder tumors and three males with tumors in the ureter and renal pelvis.
Histological features included small round blue cells with a high nuclear-to-cytoplasmic ratio, finely granular chromatin, inconspicuous nucleoli, frequent mitoses, and focal coagulative necrosis.
All cases showed diffuse POU2F3 expression, while conventional neuroendocrine markers (CgA and Syn) were lost.
NGS revealed a TP53 missense mutation (p.V225I) in one case.
Distant metastases occurred in three patients during follow-up.
Interpretation:
POU2F3 may serve as a useful marker for identifying urinary tract SmCC with absent or low neuroendocrine marker expression.
Limitations:
The study is based on a small sample size of five cases.
Limited follow-up data may affect the understanding of long-term outcomes.
Potential biases inherent in retrospective studies.
Conclusion:
POU2F3 expression could improve diagnostic accuracy and facilitate recognition of a potential neuroendocrine-low phenotype in urinary tract SmCC.
