Chromogranin has been found in several endocrine tissues, such as the pituitary, pancreas, thyroid, and parathyroid, using immunohistochemical techniques. Chromogranin immunoreactivity is characterized by a tiny granular structure in neuroendocrine cells. It is generally agreed upon that the coexistence of chromogranin and specific keratins indicates a neuroendocrine origin. Paraganglioma should be considered if there is intense chromogranin staining and no keratin staining. Neuroendocrine tumors are characterized by the co-expression of chromogranin and NSE.