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

GP consist of three components (1) ganglion cells, (2) epithelioid cells (neuroendocrine-like), and (3) spindle cells (schwannoma-like). The microscopic differential diagnosis includes poorly differentiated carcinoma, neuroendocrine tumour and paraganglioma.

GPs may be sporadic or arise in the context neurofibromatosis type 1.

GISTs may present with trouble swallowing, gastrointestinal bleeding, or metastases (mainly in the liver). Intestinal obstruction is rare, due to the tumor's outward pattern of growth. Often, there is a history of vague abdominal pain or discomfort, and the tumor has become rather large by time the diagnosis is made.

Most paragangliomas are either asymptomatic or present as a painless mass. While all contain neurosecretory granules, only in 1–3% of cases is secretion of hormones such as catecholamines abundant enough to be clinically significant; in that case manifestations often resemble those of pheochromocytomas (intra-medullary paraganglioma).

Most patients present clinically with progressive, one sided hearing loss, much more often of the sensorineural rather than conductive type. Patients may also experience tinnitus, vertigo, and loss of vestibular function (ataxia). Symptoms are usually present for a long time, which supports the slow growth of these tumors. Patients may also present with other symptoms related to von Hippel-Lindau syndrome in other anatomic sites, which will result in imaging evaluation of the head.

About 85% of paragangliomas develop in the abdomen; only 12% develop in the chest and 3% in the head and neck region (the latter are the most likely to be symptomatic). While most are single, rare multiple cases occur (usually in a hereditary syndrome). Paragangliomas are described by their site of origin and are often given special names:

- Carotid paraganglioma (carotid body tumor): Is the most common of the head and neck paragangliomas. It usually presents as a painless neck mass, but larger tumors may cause cranial nerve palsies, usually of the vagus nerve and hypoglossal nerve.

- Organ of Zuckerkandl: A collection of paraganglia near the bifurcation of the aorta, comprising a small mass of neural crest-derived chromaffin cells. Serves as a common origin of abdominal paragangliomas.

- Glomus tympanicum and Glomus jugulare: Both commonly present as a middle ear mass resulting in tinnitus (in 80%) and hearing loss (in 60%). The cranial nerves of the jugular foramen may be compressed, resulting swallowing difficulty, or ipsilateral weakness of the upper trapezius and sternocleiodomastoid muscles (from compression of the spinal accessory nerve). These patients present with a reddish bulge behind an intact ear drum. This condition is also known as the "Red drum". On application of pressure to the external ear canal with the help of a pneumatic ear speculum the mass could be seen to blanch. This sign is known as "Brown's sign". A deficient bony plate along the tympanic portion of the internal carotid artery (aberrant ICA) is a normal variant and can be mistaken with glomus jugulare.

- Vagal paraganglioma: These are the least common of the head and neck paragangliomas. They usually present as a painless neck mass, but may result in dysphagia and hoarseness.

- Pulmonary paraganglioma: These occur in the lung and may be either single or multiple.

- Other sites: Rare sites of involvement are the larynx, nasal cavity, paranasal sinuses, thyroid gland, and the thoracic inlet, as well as the bladder in extremely rare cases.

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.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. GISTs arise in the smooth muscle pacemaker interstitial cell of Cajal, or similar cells. They are defined as tumors whose behavior is driven by mutations in the KIT gene (85%), PDGFRA gene (10%), or BRAF kinase (rare). 95% of GISTs stain positively for KIT (CD117). Most (66%) occur in the stomach and gastric GISTs have a lower malignant potential than tumors found elsewhere in the GI tract.

Imaging studies help to identify the tumor and the specific anatomic site of involvement. Magnetic resonance images show a hyperintensity (hypervascularity) of a heterogeneous mass by T1 weighted images. Computed tomography shows a multilocular, lytic destructive temporal bone mass, centered within the endolymphatic sac (between internal auditory canal and sigmoid sinus).

Ceruminous adenoma are rare tumors, accounting for less than 1% of all external ear tumors. The patients will present with a mass, perhaps associated pain, and may have changes in hearing (usually a sensorineural or a conductive hearing loss). Some patients have tinnitus. Nerve paralysis is very uncommon.

This uncommon tumor accounts for less than 2% of all ear tumors. While patients present with symptoms related to the middle ear cavity location of the tumor, the tumor may expand into the adjacent structures (external auditory canal, mastoid bone, and eustachian tube). Patients come to clinical attention with unilateral (one sided) hearing loss, usually associated with decreased auditory acuity, and particularly conductive hearing loss if the ossicular bone chain (middle ear bones) is involved. Tinnitus (ringing), otitis media, pressure or occasionally ear discharge are seen. At the time of otoscopic exam, the tympanic membrane is usually intact, with a fluid level or mass noted behind the ear drum. Even though this is a "neuroendocrine" type tumor, there is almost never evidence of neuroendocrine function clinically or by laboratory examination.

Gangliogliomas are generally benign WHO grade I tumors; the presence of anaplastic changes in the glial component is considered to represent WHO grade III (anaplastic ganglioglioma). Criteria for WHO grade II have been suggested, but are not established. Malignant transformation of spinal ganglioglioma has been seen in only a select few cases. Poor prognostic factors for adults with gangliogliomas include older age at diagnosis, male sex, and malignant histologic features.

Neuroendocrine adenoma of the middle ear (NAME) is a tumor which arises from a specific anatomic site: middle ear. NAME is a benign glandular neoplasm of middle ear showing histologic and immunohistochemical neuroendocrine and mucin-secreting differentiation (biphasic or dual differentiation).

The Carney complex is a distinct entity, characterized by myxomatous neoplasms (cardiac, endocrine, cutaneous and neural), and a host of pigmented lesions of the skin and mucosae, including the rarely occurring epitheloid blue nevus.

Ganglioglioma is a rare, slow-growing primary central nervous system (CNS) tumor which most frequently occurs in the temporal lobes of children and young adults.

A ceruminous adenoma (also known as adenoma of the ceruminous gland and ceruminoma) is a benign glandular neoplasm which arises from the ceruminous glands located within the external auditory canal. These glands are found within the outer one third to one half of the external auditory canal, more common along the posterior surface; therefore, the tumor develops within a very specific location.

The World Health Organization (WHO) classification scheme places neuroendocrine tumors into three main categories, which emphasize the tumor grade rather than the anatomical origin:

- well-differentiated neuroendocrine tumours, further subdivided into tumors with benign and those with uncertain behavior

- well-differentiated (low grade) neuroendocrine carcinomas with low-grade malignant behavior

- poorly differentiated (high grade) neuroendocrine carcinomas, which are the large cell neuroendocrine and small cell carcinomas.

Additionally, the WHO scheme recognizes mixed tumors with both neuroendocrine and epithelial carcinoma features, such as goblet cell cancer, a rare gastrointestinal tract tumor.

Placing a given tumor into one of categories depends on well-defined histological features: size, lymphovascular invasion, mitotic counts, Ki-67 labelling index, invasion of adjacent organs, presence of metastases and whether they produce hormones.

Conceptually, there are two main types of NET within this category: those which arise from the gastrointestinal (GI) system and those that arise from the pancreas. In usage, the term "carcinoid" has often been applied to both, although sometimes it is restrictively applied to NETs of GI origin (as herein), or alternatively to those tumors which secrete functional hormones or polypeptides associated with clinical symptoms, as discussed.

The signs and symptoms of a pheochromocytoma are those of sympathetic nervous system hyperactivity, including:

- Skin sensations

- Flank pain

- Elevated heart rate

- Elevated blood pressure, including paroxysmal (sporadic, episodic) high blood pressure, which sometimes can be more difficult to detect; another clue to the presence of pheochromocytoma is orthostatic hypotension (a fall in systolic blood pressure greater than 20 mmHg or a fall in diastolic blood pressure greater than 10 mmHg upon standing)

- Palpitations

- Anxiety often resembling that of a panic attack

- Diaphoresis (excessive sweating)

- Headaches – most common symptom

- Pallor

- Weight loss

- Localized amyloid deposits found microscopically

- Elevated blood glucose level (due primarily to catecholamine stimulation of lipolysis (breakdown of stored fat) leading to high levels of free fatty acids and the subsequent inhibition of glucose uptake by muscle cells. Further, stimulation of beta-adrenergic receptors leads to glycogenolysis and gluconeogenesis and thus elevation of blood glucose levels).

A pheochromocytoma can also cause resistant arterial hypertension. A pheochromocytoma can be fatal if it causes a hypertensive emergency, that is, severely high blood pressure that impairs one or more organ systems (formerly called "malignant hypertension"). This hypertension is not well controlled with standard blood pressure medications.

Not all patients experience all of the signs and symptoms listed. The most common presentation is headache, excessive sweating, and increased heart rate, with the attack subsiding in less than one hour.

Tumors may grow large, but most are smaller than .

Neurocristopathy is a diverse class of pathologies that may arise from defects in the development of tissues containing cells commonly derived from the embryonic neural crest cell lineage. The term was coined by Robert P. Bolande in 1974.

Accepted examples are piebaldism, Waardenburg syndrome, Hirschsprung disease, Ondine's curse (congenital central hypoventilation syndrome), pheochromocytoma, paraganglioma, Merkel cell carcinoma, multiple endocrine neoplasia, neurofibromatosis type I, CHARGE syndrome, familial dysautonomia, DiGeorge syndrome, Axenfeld-Rieger syndrome, Goldenhar syndrome (a.k.a. hemifacial microsomia), craniofrontonasal syndrome, congenital melanocytic nevus, melanoma, and certain congenital heart defects of the outflow tract, in particular.

Multiple sclerosis has also been suggested as being neurocristopathic in origin.

The usefulness of the definition resides in its ability to refer to a potentially common etiological factor for certain neoplasms and/or congenital malformation associations that are otherwise difficult to group with other means of nosology.

In adults, approximately 80% of pheochromocytomas are unilateral and solitary, 10% are bilateral, and 10% are extra-adrenal. In children, a quarter of tumors are bilateral, and an additional quarter are extra-adrenal. Solitary lesions inexplicably favor the right side. Although pheochromocytomas may grow to large size (>3 kg), most weigh <100 g and are <10 cm in diameter. Pheochromocytomas are highly vascular.

The tumors are made up of large, polyhedral, pleomorphic chromaffin cells. Fewer than 10% of these tumors are malignant. As with several other endocrine tumors, malignancy cannot be determined from the histologic appearance; tumors that contain large number of aneuploid or tetraploid cells, as determined by flow cytometry, are more likely to recur. Local invasion of surrounding tissues or distant metastases indicate malignancy.

Extra-adrenal pheochromocytomas:

Extra-adrenal pheochromocytomas usually weigh 20 to 40 g and are <5 cm in diameter. Most are located within the abdomen in association with the celiac, superior mesenteric, and inferior mesenteric ganglia and the organ of Zuckerkandl. Approximately 10% are in the thorax, 1% are within the urinary bladder, and less than 3% are in the neck, usually in association with the sympathetic ganglia or the extracranial branches of the ninth cranial nerves.

A cancer syndrome or family cancer syndrome is a genetic disorder in which inherited genetic mutations in one or more genes predispose the affected individuals to the development of cancers and may also cause the early onset of these cancers. Cancer syndromes often show not only a high lifetime risk of developing cancer, but also the development of multiple independent primary tumors. Many of these syndromes are caused by mutations in tumor suppressor genes, genes that are involved in protecting the cell from turning cancerous. Other genes that may be affected are DNA repair genes, oncogenes and genes involved in the production of blood vessels (angiogenesis). Common examples of inherited cancer syndromes are hereditary breast-ovarian cancer syndrome and hereditary non-polyposis colon cancer (Lynch syndrome).

Hereditary cancer syndromes underlie 5 to 10% of all cancers. Scientific understanding of cancer susceptibility syndromes is actively expanding: additional syndromes are being found, the underlying biology is becoming clearer, and commercialization of diagnostic genetics methodology is improving clinical access. Given the prevalence of breast and colon cancer, the most widely recognized syndromes include hereditary breast-ovarian cancer syndrome (HBOC) and hereditary non-polyposis colon cancer (HNPCC, Lynch syndrome).

Some rare cancers are strongly associated with hereditary cancer predisposition syndromes. Genetic testing should be considered with adrenocortical carcinoma; carcinoid tumors; diffuse gastric cancer; fallopian tube/primary peritoneal cancer; leiomyosarcoma; medullary thyroid cancer; paraganglioma/pheochromocytoma; renal cell carcinoma of chromophobe, hybrid oncocytic, or oncocytoma histology; sebaceous carcinoma; and sex cord tumors with annular tubules. Primary care physicians can identify people who are at risk of heridatary cancer syndrome.

Although testicular cancer can be derived from any cell type found in the testicles, more than 95% of testicular cancers are germ cell tumors (GCTs). Most of the remaining 5% are sex cord-gonadal stromal tumours derived from Leydig cells or Sertoli cells. Correct diagnosis is necessary to ensure the most effective and appropriate treatment. To some extent, this can be done via blood tests for tumor markers, but definitive diagnosis requires examination of the histology of a specimen by a pathologist.

Most pathologists use the World Health Organization classification system for testicular tumors:

- Germ cell tumors

- "Precursor lesions"

- Intratubular germ cell neoplasia

- Unclassified type (carcinoma in situ)

- Specified types

- "Tumors of one histologic type (pure forms)"

- Seminoma

- Variant - Seminoma with syncytiotrophoblastic cells

- Spermatocytic seminoma

- Variant - spermatocytic seminoma with sarcoma

- Embryonal carcinoma

- Yolk sac tumor

- Trophoblastic tumors

- Choriocarcinoma

- Variant - monophasic choriocarcinoma

- Placental site trophoblastic tumour

- Cystic trophoblastic tumor

- Teratoma

- Variant - Dermoid cyst

- Variant - Epidermoid cyst

- Variant - Monodermal teratoma (Carcinoid, Primitive neuroectodermal tumor (PNET), Nephroblastoma-like tumor, others.

- Variant - Teratomic with somatic-type malignancy

- "Tumours of more than one histologic type (mixed forms)"

- Embryonal carcinoma and teratoma

- Teratoma and seminoma

- Choriocarcinoma and teratoma.embryonal carcinoma

- Others

- Sex cord/Gonadal stromal tumors

- Leydig cell tumor

- Sertoli cell tumor

- Lipid rich variant

- Scleriosing variant

- Large cell calcifying variant

- Intratubular sertoli cell neoplasia in Peutz-Jeghers syndrome

- Granulosa cell tumor

- Adult type

- Juvenile type

- Thecoma Fibroma Group

- Thecoma

- Fibroma

- Sex cord/gonadal stromal tumor - incompletely differentiated

- Sex cord/gonadal stromal tumor - mixed types

- Mixed Germ Cell and Sex Cord/Gonadal Stromal Tumors

- Gonadoblastoma

- Germ cell-sex cord/gonadal stromal tumor, unclassified

- Miscellaneous tumours of the testis

- Carcinoid

- Tumors of ovarian epithelial types

- Serous tumor of borderline malignancy

- Serous carcinoma

- Well differentiated endometrioid tumor

- Mucinous cystadenoma

- Mucinous cystadenocarcinoma

- Brenner tumor

- Nephroblastoma

- Paraganglioma

- Haematopoietic tumors

- Tumours of collecting ducts and rete

- Adenoma

- Carcinoma

- Tumors of the paratesticular structures

- Adenomatoid tumor

- Malignant and Benign Mesothelioma

- Adenocarcinoma of the epididymis

- Papillary cystadenoma of the epididymis

- Melanotic neuroectodermal tumor

- Desmoplastic small round cell tumor

- Mesenchymal tumors of the spermatic cord and testicular adnexae

- Lipoma

- Liposarcoma

- Rhabdomyosarcoma

- Aggressive angiomyxoma

- Angiomyofibroblastoma-like tumor (see Myxoma)

- Fibromatosis

- Fibroma

- Solitary fibrous tumor

- Others

- Secondary tumors of the testis

One of the first signs of testicular cancer is often a lump or swelling in the testes. The U.S. Preventive Services Task Force (USPSTF) recommends against routine screening for testicular cancer in asymptomatic adolescent and adults including routine testicular self-exams. However, the American Cancer Society suggests that some men should examine their testicles monthly, especially if they have a family history of cancer, and the American Urological Association recommends monthly testicular self-examinations for all young men.

Symptoms may also include one or more of the following:

- a lump in one testis which may or may not be painful

- sharp pain or a dull ache in the lower abdomen or scrotum

- a feeling often described as "heaviness" in the scrotum

- breast enlargement (gynecomastia) from hormonal effects of β-hCG

- low back pain (lumbago) due to the cancer spreading to the lymph nodes along the back

It is not very common for testicular cancer to spread to other organs, apart from the lungs. If it has, however, the following symptoms may be present:

- shortness of breath (dyspnea), cough or coughing up blood (hemoptysis) from metastatic spread to the lungs

- a lump in the neck due to metastases to the lymph nodes

Testicular cancer, cryptorchidism, hypospadias, and poor semen quality make up the syndrome known as testicular dysgenesis syndrome.