Neuroendocrine cells are specialized cells that function as part of both the nervous and endocrine systems of the body. Neuroendocrine cells are found throughout the body. Normal neuroendocrine cells are often hard to see under the microscope because they are small and hidden between other types of cells. When examined on a routine H&E stained slide, the nucleus of the cell is typically round and the chromatin (genetic material) inside of the nucleus is arranged in small groups. Pathologists describe this pattern as “salt and pepper” chromatin. Some cells have larger clumps of genetic material called nucleoli.
Tumours made up of neuroendocrine cells are called neuroendocrine tumours. There are many different types of neuroendocrine tumours and the name of the tumour depends on the location in the body where the tumour starts, the way the tumour looks when examined under the microscope, and the types of hormones produced by the tumour cells.
Types of neuroendocrine tumours include:
Cancers made up of neuroendocrine cells are called neuroendocrine carcinoma. In some areas of the body, neuroendocrine carcinoma is divided into two types based on the size and shape of the cancer cells in the tumour. For example, tumours made up of small cells are called small cell neuroendocrine carcinoma while those made up of large cells are called large cell neuroendocrine carcinoma.
Pathologists can perform a test called immunohistochemistry to identify these cells under the microscope. Pathologists usually look for three proteins called synaptophysin, chromogranin, and CD56 which are made by both normal neuroendocrine cells and tumours made up of these cells.