Neuroendocrine differentiation is diffusely seen in this case of prostatic adenocarcinoma. About 50% of the tumor cells have bright eosinophilic granules in their cytoplasm. Majority of such cells stain with antibodies to serotonin and chromogranin. A variety of other neuroendocrine markers have been detected in numerous studies. Although these cells resemble Paneth cells of small intestine, they lack lysozyme activity.