A pheochromocytoma is another, rarer type of NET that usually develops in the adrenal gland, but can also arise in other parts of the body.
Signs and symptoms depend on the tumor's type, size and location; whether it produces hormones; and whether it has spread to other parts of the body (metastasized). NETs are typically described as functional or nonfunctional. Functional NETs produce a specific set of symptoms due to the production of excess hormones, while non-functional NETs generally do not cause specific symptoms. In many cases, a person has no symptoms until the tumor spreads to the liver and/or impairs the function of an organ or system. This can make NETs very hard to diagnose. The majority of NETs are not inherited and occur sporadically in people with no family history of NETs. However, some NETs are associated with a hereditary cancer or tumor syndrome such as multiple endocrine neoplasia type 1 (most commonly), Von Hippel-Lindau disease, tuberous sclerosis, or neurofibromatosis type 1 (NF1). Inheritance of each of these is autosomal dominant. Treatment of NETs depends on many factors such as the tumor's type, location, aggressiveness, and hormone-producing capabilities; as well as whether it has metastasized. Management options may include surveillance, surgery to remove the tumor and/or surrounding tissue, and various non-surgical therapies to shrink the tumor, stop it from growing, or manage symptoms.