The presentation may depend on the site:

• Pituitary: Microadenoams may will be asymptomatic, but macroadenomas will cause symptoms due to their mass effect on structures around it. There may be headache and if the adenoma is big enough it may compress the optic chiasma causing visual field loss. Other clinical aspects will depend if the adenoma is secreting hormones such as growth hormone, which may lead to a clinical syndrome called acromegaly [7].
• Colon: Most colonic polyps are be asymptomatic. The most common symptom being rectal bleeding. Constipation or diarrhea may occur.
• Adrenal: The symptoms are dependent on the hormone that is being secreted, if any at all. In case of pheochromocytoma, then symptoms that are adrenergic should be sought. Other hormones such as aldosterone may present with electrolyte imbalance symptoms. Corticosteroid excess will present with Cushing syndrome.
• Thyroid: About 10% of people have an isolated thyroid nodule. Most will be asymptomatic and may present with pressure symptoms only if it is large enough. The few that secrete hormones will have symptoms of hyperthyroidism such as weight loss, irritability, heat intolerance and cardiac rhythm abnormalities like atrial fibrillation.
• Parathyroid: These may secrete parathyroid hormone and cause primary hyperparathyroidism which will present with symptoms of calcium excess. The clinical syndrome will present with the classic bones, stones, abdominal groans and psychic moans [8] [9] [10].

• Pain

  Center: Sessile, centrally depressed polyp in the descending duodenum of a 64 year-old woman undergoing endoscopy for evaluation of abdominal pain. The lesion was a benign adenoma on biopsy. [endoatlas.com]

  These tumors vary in their behavior, from locally aggressive to blatantly malignant, and are sometimes associated with pain or tenderness. [parotidsurgerymd.com]

  Pancreas: pain in the abdomen, diarrhea, stomach pain, persistent fatigue, fainting, and weight gain can indicate one of the various types of pancreatic adenomas or pancreatic cancer. [encyclopedia.com]

  A 48 years old male patient admitted to the gastroenterology clinic due to the epigastric pain spreading dorsally. No significant feature is present in his clinical history. [ncbi.nlm.nih.gov]

• Falling

  Dieser Bericht beschreibt den Fall eines 58 Jahre alten Mannes mit Hämoptoe. Radiologisch fand sich eine solitäre pulmonale Raumforderung ohne Anzeichen von Malignität. [zora.uzh.ch]

  Pituitary adenomas don't fall under the category of brain and central nervous system tumours. Instead they are tumours of the endocrine system which is responsible for the secretion or release of various hormones into the bloodstream. [thebraintumourcharity.org]

  If not stimulated by these acts, prolactin production normally falls. In women, prolactinomas can cause galactorrhea, the inappropriate production of milk; that is, milk is produced even though a woman is neither pregnant nor nursing. [study.com]

  The problems caused by pituitary tumors fall into three general categories: 1. Hypersecretion - too much of any hormone in the body is caused by a functioning pituitary tumor 2. [hormone.org]

  Laryngo-Rhino-Otol 2006; 85(1): 46-49 DOI: 10.1055/s-2005-870107 Der interessante Fall © Georg Thieme Verlag KG Stuttgart · New York Middle-ear Adenoma 1Universitäts-Hals-Nasen-Ohren-Klinik, Mannheim (Direktor: Prof. Dr. med. [thieme-connect.com]

• Chills

  Photo Credit Dolly Faibyshev for The New York Times Work Out and Chill? Cool temperature workouts may be the answer for those who want to exercise without becoming a hot mess. [nytimes.com]

  Lung: a chronic or bloody cough, fever, chills, and shortness of breath can indicate a bronchial adenoma. [encyclopedia.com]

• Short Stature

  Growth hormone-secreting adenomas can increase ICP in a fashion similar to those in children taking growth hormone for short stature or patients with Turner syndrome who develop idiopathic intracranial hypertension. [eyewiki.aao.org]

• Recurrent Urinary Tract Infection

  In evaluating pro-inflammatory factors, 26.7% underwent either Bacillus Calmette-Guerin or mitomycin C, 30% had recurrent urinary tract infections, and 25% had a history of catheterization. [ncbi.nlm.nih.gov]

• Nausea

  Symptoms may include headache, nausea, visual loss, double vision and confusion. Most patients have undiagnosed hormone insufficiency prior to the apoplectic event. Pituitary Apoplexy is best confirmed by MRI. [brain-tumor.org]

  Symptoms may include: Headache Nausea Visual loss Double vision Confusion Most patients have undiagnosed hormone insufficiency prior to the apoplectic event. Pituitary apoplexy is best confirmed by MRI. [pacificneuroscienceinstitute.org]

  These might include: mental changes such as depression, lethargy, or confusion nausea vomiting pain in your muscles or abdomen Sometimes, doctors aren’t sure what causes a tumor to appear on one of your glands. [healthline.com]

  Symptoms may include any of the following: Confusion Constipation Lack of energy ( lethargy ) Muscle pain Nausea or decreased appetite Urinating more often at night Weak bones or fractures Blood tests may be done to check levels of: PTH Calcium Phosphorus [nlm.nih.gov]

• Vomiting

  These might include: mental changes such as depression, lethargy, or confusion nausea vomiting pain in your muscles or abdomen Sometimes, doctors aren’t sure what causes a tumor to appear on one of your glands. [healthline.com]

  (ACTH), which triggers the adrenal glands to make steroid hormones Hyperthyroidism from too much thyroid stimulating hormone (TSH) Some general symptoms of pituitary adenomas include: Headaches Vision problems (double vision, vision loss) Nausea or vomiting [my.clevelandclinic.org]

  Occasionally, however, they move to the chest, along with the thymus. 1 Most patients with hyperparathyroidism are asymptomatic, but any symptoms that do appear are generally caused by hypercalcemia, and include nausea, vomiting, excessive thirst, constipation [archbronconeumol.org]

  Possible side effects from chemo include: Fatigue Nausea and vomiting Hair loss Loss of appetite Diarrhea Increased risk of infection Immunotherapy. This treatment uses medicine to boost your immune system's ability to find and destroy cancer. [webmd.com]

• Abdominal Mass

  Clinical manifestation may include epigastric or abdominal pain, weight loss, diabetes, jaundice and palpable abdominal mass. Some patients have no symptoms and the tumor is discovered incidentally. [orpha.net]

  Hepatic adenomas are diagnosed when they cause epigastric or upper quadrant pain or during an imaging study done for unrelated ailments, and less commonly when an abdominal mass is palpated on clinical examination. [intechopen.com]

• Hypertension

  Multi-drug resistant hypertension. Hypertension with spontaneous or diuretic-induced hypokalemia. Hypertension with an incidentally discovered adrenal mass. [cancertherapyadvisor.com]

  We report a case of thirty three years old Javanese female presented with uncontrolled hypertension, muscular weakness, cramps and progressing shortness of breath during working for 6 years. She had history of hypertension since age 20. [ncbi.nlm.nih.gov]

  Primary aldosteronism is the most frequent form of secondary hypertension accounting for up to 5-10% of all hypertensive patients and it is caused by bilateral idiopathic hyperplasia in approximately two-thirds of cases and aldosterone-producing adenoma [ensat.org]

• Visual Impairment

  The patient was symptom free for three and a half years when she returned with complaint of visual impairment. Perimetry test revealed visual field defect of bitemporal hemianopia. [intjcancermanag.com]

  In the remaining 40 per cent of patients the visual field impairment remained, however, it should be noted that in one group of these patients a permanent visual impairment had been previously diagnosed and as a result significant improvements in their [dren-trogrlic.com]

  If the patient develops visual impairment or the tumor begins to compress visual pathways, further surgery is indicated. [scielo.br]

  In 1986, a 60-year-old man developed the gradual onset of painless visual impairment in his left eye. He was seen by a retinal specialist and was treated with laser photocoagulation for a presumed CNVM on the temporal margin of the optic disc. [jamanetwork.com]

• Hyperpigmentation

  […] hormone (~25%) Acromegaly : bone enlargement in hand/feet/skull, prominent jaw, cardiomegaly, heat intolerance, weight gain ACTH (~20%) Cushing's disease : central obesity (moon facies, buffalo hump), thin skin with striae, hirsutism Nelson's syndrome : hyperpigmentation [en.wikibooks.org]

  […] carcinoma – Usually proximal bronchi and may be more common on the left side of the tracheobronchial tree Paraneoplastic involvement Endocrinopathies associated with bronchial carcinoids include Cushing syndrome (with increased corticotropin levels), hyperpigmentation [emedicine.medscape.com]

  Approximately 25 percent of patients with MEN1 develop pituitary adenomas.[20][21] Carney complex[edit] Carney complex (CNC), also known as LAMB syndrome[22] and NAME syndrome[22] is an autosomal dominant condition comprising myxomas of the heart and skin, hyperpigmentation [en.wikipedia.org]

  They may also develop hyperpigmentation, which occurs due to the stimulation of melanocytes by POMC. [eyewiki.aao.org]

The workup is dependent on the site of the adenoma and the symptoms that it is causing.

• In case of adenoma of the brain, magnetic resonance imaging is the recommended modality as the adenoma may be seen and this will allow planning for treatment if warranted. 
• For the colon if there is a family history of polyps, whole colon colonoscopy is mandatory otherwise, screening as per local guidelines is recommended.
• Adrenal adenomas most are found incidentally by CT scan and if there are no symptoms suggestive of hormonal secretion, no more laboratory testing is required. 
• For the thyroid gland, ultrasound is the modality of choice, with indications for biopsy being determined by features noted on the ultrasound. Thyroid function tests will also be required to examine the hormone levels.
• Parathyroid adenomas that are symptomatic will require investigations that include calcium levels, urinary calcium levels, renal function tests and parathyroid hormone levels.

• Polyps

  Note: many gastroenterologists use the term "serrated polyp" to mean "sessile serrated adenoma/polyp Be cautious about using this as a descriptive term even though hyperplastic polyps are serrated too Covered separately Traditional serrated adenoma Background [surgpathcriteria.stanford.edu]

  The gross appearance was more suggestive of a polyp at this exam. Histology was consistent with complete polyp excision. [endoatlas.com]

  Abstract Traditional serrated adenoma (TSA) is a type of serrated polyp of the colorectum and is thought to be a precancerous lesion. There are three types of serrated polyps, namely, hyperplastic polyps, sessile serrated adenomas/polyps, and TSAs. [ncbi.nlm.nih.gov]

  The colonoscopic appearance of rectal polyps that proved to be tubular adenomas are seen below. [library.med.utah.edu]

• Hepatocellular Carcinoma

  Positivity for either indicate well-differentiated hepatocellular carcinoma or hepatocellular carcinoma ex adenoma. Beta catenin staining is typically membranous, though nuclear staining may be seen. [cedars-sinai.org]

  Focal nodular hyperplasia may be a precursor for fibrolamellar hepatocellular carcinoma. Elective resection of hepatic adenoma has a mortality rate of less than 1 per cent, while the mortality rate with free rupture is 5 to 10 per cent. [ncbi.nlm.nih.gov]

  General imaging differential considerations include: hepatocellular carcinoma (HCC) washout tends to leave the lesion hypointense to the liver rim enhancement of the pseudocapsule may persist on the delayed scan different demographics may be difficult [radiopaedia.org]

The treatment of an adenoma will depend entirely on the location and other symptoms caused by the tumor. Many are asymptomatic and will never require any treatment or follow-up. The symptomatic ones may require surgical removal.

The prognosis varies from the site, but the grade of dysmorphic cells and dysplasia is prognostic, with high grades being more prone to malignant transformation than lower grades. There are some familial adenoma syndromes such as familial adenomatous polyposis which is known to have a high propensity for malignant transformation.

An adenoma occurs due to an abnormal cell proliferation and defective apoptosis. There are believed to be multiple steps in the progression from normal tissue to adenoma, and then ultimately to adenocarcinoma. The processes differs from site to site and involve loss of tumor suppressor genes and activation of oncogenes. Some of these genetic aberrations may be genetically passed down like in familial adenomatous polyposis (FAP), some may be due to external carcinogens.

The epidemiology of adenomas varies from site of origin. The list is not exhaustive:

• Pituitary adenomas represent about 12.5% of all brain tumours [2].
• Population autopsy studies suggest that approximately 30% of people above 40 years of age have colonic adenomas called polyps [3].
• Most adrenal adenomas are found incidentally and are termed incidentaloma and their prevalence ranges from 0.4 to 8.7% from autopsy and CT scan studies [4].
• About 10% of people have an isolated thyroid nodules. Some may require excision of biopsy, and other may secrete hormones [5].
• Parathyroid adenomas may secrete parathyroid hormone and cause primary hyperparathyroidism [6].

The biochemical processes that lead to adenoma formation depend on the location and the underlying cell type. There may be an interplay of genetic and environmental factors with organs exposed to the environment being at higher risk. The tumorgenesis for many of these is just beginning to be elucidated.

Since most are caused by cell proliferation, it is difficult to prevent adenomas. The important aspect it to find the ominous ones early and treat them appropriately to prevent malignant transformation. Families with a strong family history of adenomas like colonic polyps will require screening.

An adenoma is a benign epithelial tumor with glandular origin, glandular characteristics, or both. It may become malignant and can also appear in non-glandular areas. The malignant transformation is rare. It may cause of other complications such as compressive symptoms and autonomous hormone secretion [1]. The adenomas may be at different levels of dysplasia, with the ones with more dysplastic characteristics, having more potential for malignant transformation.

Definition

Adenomas are small swellings that can occur in many locations in the body. Most of them are innocent, but some may cause trouble if they are big enough and compress nearby structures. They have a small potential to become cancers.

Cause

The cause of the growths is unknown, but there is ongoing research into genetics with information growing.

Symptoms

These depend on the site. In the brain there may be headache and problems with eye site. If they are in the colon there may be constipation or diarrhea otherwise most are asymptomatic. Adrenal tumours may secrete hormones that may cause different symptoms such a weight gain and diabetes if corticosteroid are being made, or episodes of palpitations and flushing if adrenaline is being made. Thyroid adenomas may cause a disease called hyperthyroidism which is presents with heat intolerance and weight loss. Parathyroid adenomas may present with symptoms of too much calcium in the body such as aches and stomach pains.

Diagnosis

Diagnosis is dependent on the site, for the brain a CT scan or magnetic resonance imaging may be used. For the colon a colonoscopy. For adrenal adenomas a CT scan and blood tests to check hormone levels may be done. The same for parathyroid adenomas. For thyroid adenomas an ultrasound may be required and a small piece taken for testing.

Treatment

The response of your doctor will depend on the site and the symptoms and the local guidelines. They may requiring occasional screening or removal by surgery if required.

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9. Nieman LK. Approach to the patient with an adrenal incidentaloma. J Clin Endocrinol Metab. Sep 2010;95(9):4106-13
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