This is a very rare tumor, since only about 1 in 35,000 to 40,000 people have VHL, of whom about 10% have endolymphatic sac tumors. Patients usually present in the 4th to 5th decades without an gender predilection. The tumor involves the endolymphatic sac, a portion of the intraosseous inner ear of the posterior petrous bone.

While there is a wide age range at clinical presentation (12–85 years), most patients come to clinical attention at 55 years (mean). There is no gender difference.

Carney triad (CT) is characterized by the coexistence of three types of neoplasms, mainly in young women, including gastric gastrointestinal stromal tumor, pulmonary chondroma, and extra-adrenal paraganglioma. The underlying genetic defect remains elusive. CT is distinct from Carney complex, and the Carney-Stratakis syndrome.

Pheochromocytoma is seen in between two and eight in 1,000,000, with approximately 1000 cases diagnosed in United States yearly. It mostly occurs in young or middle age adults, though it presents earlier in hereditary cases.

- About 10% of adrenal cases are bilateral (suggesting hereditary disease)

- About 10% of adrenal cases occur in children (also suggesting hereditary disease)

- About 15% are extra-adrenal (located in any orthosympathetic tissue): Of these 9% are in the abdomen, and 1% are located elsewhere. Some extra-adrenal pheochromocytomas are probably actually paragangliomas, but the distinction can only be drawn after surgical resection.

- About 11.1% of adrenal cases are malignant, but this rises to 30% for extra-adrenal cases

- About 15–20% are hereditary

- About 5% are caused by VHL disease

- About 3% recur after being resected

- About 14% of affected individuals do not have arterial hypertension (Campbell's Urology)

There is increased life-time risk of secondary cancers (relative risk 3.63), with a slightly increased mortality risk (1.21) according to a 2004 Swedish study of 481 patients.

Fundic gland polyps are found in 0.8 to 1.9% of patients who undergo esophagogastroduodenoscopy, and are more common in middle aged women.

The most important consideration in evaluating patients with FGPs is distinguishing between sporadic form (patients without any other gastrointestinal condition, usually in middle age with female prevalence) and syndromic form. This is to ascertain the risk of development of gastric cancer, and to ascertain the risk of concomitant colon cancer.

FGPs can be found in association with the following genetic conditions:

- familial adenomatous polyposis

- attenuated familial adenomatous polyposis syndromes

- Zollinger-Ellison syndrome

- gastric adenocarcinoma associated with proxymal polyposis of the stomach (GAPPS): this condition, described in three families is characterized by development of antral adenomas and FGPs, with early development of severe dysplasia and gastric cancer, in absence of overt intestinal polyposis. This condition has been recently characterized by a point mutation in exon 1B of APC gene.

Sporadic FGPs have been associated with:

- chronic use of proton pump inhibitors (proposed by some authors, denied by others)

- "Helicobacter pylori" infection: there is a reverse relationship between infection and fundic gland polyps, and infection by "H pylori" causes polyps regression.

Most individuals come to clinical attention during the 5th decade, although the age range is broad (20 to 80 years). There is an equal gender distribution.

JCT often is described as benign, however one case of metastasis has been reported, so its malignant potential is uncertain. In most cases the tumor is encapsulated.

The most common presentation is gastrointestinal bleed (~45% of cases), followed by abdominal pain (~43% of cases) and anemia (~15% of cases).

Paragangliomas originate from paraganglia in chromaffin-negative glomus cells derived from the embryonic neural crest, functioning as part of the sympathetic nervous system (a branch of the autonomic nervous system). These cells normally act as special chemoreceptors located along blood vessels, particularly in the carotid bodies (at the bifurcation of the common carotid artery in the neck) and in aortic bodies (near the aortic arch).

Accordingly, paragangliomas are categorised as originating from a neural cell line in the World Health Organization classification of neuroendocrine tumors. In the categorization proposed by Wick, paragangliomas belong to group II. Given the fact that they originate from cells of the orthosympathetic system, paragangliomas are closely related to pheochromocytomas, which however are chromaffin-positive.

A paraganglioma is a rare neuroendocrine neoplasm that may develop at various body sites (including the head, neck, thorax and abdomen). Unlike other types of cancer, there is no test that determines benign from malignant tumors; long-term followup is therefore recommended for all individuals with paraganglioma. Approximately 50% of patients with recurrent disease experience distant metastasis. The five-year survival in the setting of metastatic disease is 40% to 45%.

A gangliocytic paraganglioma, abbreviated GP, is a rare tumour that is typically found in the duodenum and consists of three components: (1) ganglion cells, (2) epithelioid cells (paraganglioma-like) and, (3) spindle cells (schwannoma-like).

10-year survival rates for mucinous tumors is excellent in the absence of invasion.

In the case of borderline tumors confined to the ovary and malignant tumors without invasion, the survival rates are 90% or greater. In invasive mucinous cystadenocarcinomas, the survival is approximately 30%

GISTs occur in 10-20 per one million people. The true incidence might be higher, as novel laboratory methods are much more sensitive in diagnosing GISTs. The estimated incidence of GIST in the United States is approximately 5000 cases annually. This makes GIST the most common form of sarcoma, which constitutes more than 70 types of cancer.

The majority of GISTs present at ages 50–70 years. Across most of the age spectrum, the incidence of GIST is similar in men and women.

Adult GISTs are rare before age 40. Pediatric GISTs are considered to be biologically distinct. Unlike GISTs at other ages, pediatric GISTs are more common in girls and young women. They appear to lack oncogenic activating tyrosine kinase mutations in both KIT and PDGFRA. Pediatric GISTs are treated differently than adult GIST. Although the generally accepted definition of pediatric GIST is a tumor that is diagnosed at the age of 18 years or younger, "pediatric-type" GISTs can be seen in adults, which affects risk assessment, the role of lymph node resection, and choice of therapy.

Generally, there is a good prognosis for low-grade tumors, and a poor prognosis for high-grade tumors.

Patients treated with complete surgical excision can expect an excellent long term outcome without any problems. Recurrences may be seen in tumors which are incompletely excised.

Carney (CT), named for J Aidan Carney, is considered to be a specific type of multiple endocrine neoplasia (MEN). The three classically associated tumors are a subset of gastric epithelioid leiomyosarcoma (it is now known that this subset is actually gastrointestinal stromal tumor arising from the interstitial cells of Cajal), pulmonary chondroma, and extra-adrenal paraganglioma.

The condition manifests more commonly in females. Multiple tumors in multiple organs in young patients, with occasional sibling involvement, suggested an inherited disorder, but the underlying genetic basis has not been identified.

In addition to these three classical tumors, there is an increased incidence of pheochromocytoma, esophageal leiomyoma and adrenocortical adenoma.

The original description employed the then-prevailing terminology of gastric epithelioid leiomyosarcoma. Subsequent advances in molecular biology have led to the current terminology of gastrointestinal stromal tumors (GISTs). However, there is limited evidence to suggest that the gastrointestinal stromal tumors (GIST) in Carney triad lack CD117 (c-kit) mutations (i.e., they are wild-type), and hence these GISTs may prove unresponsive to Gleevec.

Most ganglioneuromas are noncancerous, thus expected outcome is usually good. However, a ganglioneuroma may become cancerous and spread to other areas, or it may regrow after removal.

If the tumor has been present for a long time and has pressed on the spinal cord or caused other symptoms, it may have caused irreversible damage that cannot be corrected with the surgical removal of the tumor. Compression of the spinal cord may result in paralysis, especially if the cause is not detected promptly.

Wide excision is the treatment of choice, although attempting to preserve hearing. Based on the anatomic site, it is difficult to completely remove, and so while there is a good prognosis, recurrences or persistence may be seen. There is no metastatic potential. Patients who succumb to the disease, usually do so because of other tumors within the von Hippel-Lindau complex rather than from this tumor.

There is a risk of development of cancer with fundic gland polyposis, but it varies based on the underlying cause of the polyposis. The risk is highest with congenital polyposis syndromes, and is lowest in acquired causes. As a result, it is recommended that patients with multiple fundic polyps have a colonoscopy to evaluate the colon. If there are polyps seen on colonoscopy, genetic testing and testing of family members is recommended.

In the gastric adenocarcinoma associated with proximal polyposis of the stomach (GAPPS), there is a high risk of early development of proximal gastric adenocarcinoma.

It is still unclear which patients would benefit with surveillance gastroscopy, but most physicians recommend endoscopy every one to three years to survey polyps for dysplasia or cancer. In the event of high grade dysplasia, polypectomy, which is done through the endoscopy, or partial gastrectomy may be recommended. One study showed the benefit of NSAID therapy in regression of gastric polyps, but the efficacy of this strategy (given the side effects of NSAIDs) is still dubious.

There are no known risk factors for ganglioneuromas. However, the tumors may be associated with some genetic problems, such as neurofibromatosis type 1.

Although estimates vary, the annual incidence of clinically significant neuroendocrine tumors is approximately 2.5–5 per 100,000; two thirds are carcinoid tumors and one third are other NETs.

The prevalence has been estimated as 35 per 100,000, and may be considerably higher if clinically silent tumors are included. An autopsy study of the pancreas in people who died from unrelated causes discovered a remarkably high incidence of tiny asymptomatic NETs. Routine microscopic study of three random sections of the pancreas found NETs in 1.6%, and multiple sections identified NETs in 10%. As diagnostic imaging increases in sensitivity, such as endoscopic ultrasonography, very small, clinically insignificant NETs may be coincidentally discovered; being unrelated to symptoms, such neoplasms may not require surgical excision.

Juxtaglomerular cell tumor (JCT, JGCT, also reninoma) is an extremely rare kidney tumour of the juxtaglomerular cells, with less than 100 cases reported in literature. This tumor typically secretes renin, hence the former name of reninoma. It often causes severe hypertension that is difficult to control, in adults and children, although among causes of secondary hypertension it is rare. It develops most commonly in young adults, but can be diagnosed much later in life. It is generally considered benign, but its malignant potential is uncertain.

Occurs in adults, with peak incidence from 20–40 years of age. A causal link with cytomegalovirus (CMV) has been strongly implicated in a 2011 research.

Villous adenoma is a type of polyp that grows in the colon and other places in the gastrointestinal tract and sometimes in other parts of the body. These adenomas may become malignant (cancerous). Villous adenomas have been demonstrated to contain malignant portions in about one third of affected persons, and invasive malignancy in another one third of removed specimens. Colonic resection may be required for large lesions. These can also lead to secretory diarrhea with large volume liquid stools with few formed elements. They are commonly described as secreting large amounts of mucus, resulting in hypokalaemia in patients. On endoscopy a "cauliflower' like mass is described due to villi stretching. Being an adenoma, the mass is covered in columnar epithelial cells.