A carcinoid is a tumour made up of specialized neuroendocrine cells. Most carcinoids start in the lungs where they are divided into two groups – typical carcinoid and atypical carcinoid. Carcinoid tumours can also be found in the colon and pancreas where they are usually given the name well differentiated neuroendocrine tumour.
All carcinoid tumours have the ability to spread to other parts of the body and for this reason doctors consider them to be a type of slow growing cancer. Some carcinoid tumours can produce large amount of chemicals such as serotonin that can lead to symptoms such as sweating, abdominal pain, and diarrhea. Doctors describe these symptoms as carcinoid syndrome. These symptoms typically only occur if the tumour has spread to the liver.
When examined under the microscope, carcinoid tumours are made up of cells that all look very similar. Pathologists often describe the nucleus of the cell as “salt and pepper” because the chromatin or genetic material looks like small dark dots on a white background. Additional tests such as immunohistochemistry may be performed to help make the correct diagnosis.