Routine testing for neuroendocrine component (NEC) in prostate cancer (PC) is not done for de-novo cases due to its debatable significance. But, there is growing evidence that its presence is associated with aggressive behaviour and poor prognosis. We aim to study the NEC expression in patients presenting with Gleason pattern (GP) 5 using immunohistochemistry (IHC). Our objectives are: 1- To study NEC incidence in de-novo GP 5 cases 2- To identify subsets who may benefit from routine IHC

All patients with GP 5 underwent IHC for NEC and were grouped into focal (<10% expression), intermediate (11-39%) and high (>40%). Stratification was done based on stage, PSA ( prostate specific antigen) values, Ki67 index and metastatic site. Wilcoxon rank test was used for statistical analysis.

107 patients were tested. 93% were de-novo PC. 50% were metastatic. Overall NEC was found in 60% cases with 46% having high expression. Visceral metastasis was more in patients with NEC in contrast to those without (26.5% vs 11.6%). In de-novo metastatic subgroup 57.40% of patients had NEC with 48.38% having high expression. Visceral metastasis was seen in 31.48% and 53.3% in these groups respectively. S PSA and Ki67 Values were significantly different in patients with and without NEC.

Incidence of NEC in de-novo GP5 PC is more than what has been described in literature with higher incidence of visceral metastasis at presentation. Employing IHC in this group may aid in better risk stratification, prognostication and tailored management.