Carcinoid

Carcinoid (also carcinoid tumor) is a slow-growing type of neuroendocrine tumor originating in the cells of the neuroendocrine system.

In 2000, the World Health Organization redefined "carcinoid", but this new definition has not been accepted by all practitioners. This has led to some complexity in distinguishing between carcinoid and other neuroendocrine tumors in the literature. According to the American Cancer Society, the 2000 WHO definition states:

The WHO now divides these growths into neuroendocrine tumors and neuroendocrine cancers. Neuroendocrine tumors are growths that look benign but that might possibly be able to spread to other parts of the body. Neuroendocrine cancers are abnormal growths of neuroendocrine cells which can spread to other parts of the body.

Carcinoid tumors have more benign features than neuroendocrine cancers.