Carcinoid Tumor

Higher magnification (same case as the previous image) showing solid nests of uniform tumor cells with prominent eosinophilic granules. Majority of the carcinoids are immunoreactive for neuroendocrine markers such as chromogranin, synaptophysin, CD56, and neuron-specific enolase. Other markers that may be expressed include serotonin, somatostatin, substance P, and pancreatic polypeptide. Tumors that show orange-red granules (seen in this case) are often immunoreactive for Glucagon.