Xue W, et al. - Whether insulinoma-associated protein 1 (INSM1) was a useful neuroendocrine marker to detect small cell carcinoma (SCC) of the prostate was investigated in this analysis. The performance of chromogranin and synaptophysin was used for comparison to validate its possible utility as a diagnostic marker. Findings revealed that INSM1 was positive in 92.3% of primary prostatic SCCs vs 53.8% positive for chromogranin, and 84.6% positive for synaptophysin. It was concluded that INSM1 was a novel sensitive and specific marker for detection of SCC of the prostate. Results of this study suggested that application of INSM1 in clinical pathologic diagnosis will be beneficial.