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.

Due to the diverse nature of salivary gland tumours, many different terms and classification systems have been used. Perhaps the most widely used currently is that system proposed by the World Health Organization in 2004, which classifies salivary neoplasms as primary or secondary, benign or malignant, and also by tissue of origin. This system defines five broad categories of salivary gland neoplasms:

Benign epithelial tumors

- Pleomorphic adenoma

- Warthin's tumor

- Myoepithelioma

- Basal cell adenoma

- Oncocytoma

- Canalicular adenoma

- Lymphadenoma

- "Sebaceous lymphadenoma"

- "Nonsebaceous lymphadenoma"

- Ductal papilloma

- "Inverted ductal papilloma"

- "Intraductal papilloma"

- "Sialadenoma papilliferum"

- Cystadenoma

- Malignant epithelial tumors

- Acinic cell carcinoma

- Mucoepidermoid carcinoma

- Adenoid cystic carcinoma

- Polymorphous low-grade adenocarcinoma

- Epithelial-myoepithelial carcinoma

- Clear cell carcinoma, not otherwise specified

- Basal cell adenocarcinoma

- Sebaceous carcinoma

- Sebaceous lymphadenocarcinoma

- Cystadenocarcinoma

- Low-grade cribriform cystadenocarcinoma

- Mucinous adenocarcinoma

- Oncocytic carcinoma

- Salivary duct carcinoma

- Salivary duct carcinoma, not otherwise specified

- Adenocarcinoma, not otherwise specified

- Myoepithelial carcinoma

- Carcinoma ex pleomorphic adenoma

- Mammary analogue secretory carcinoma

- Carcinosarcoma

- Metastasizing pleomorphic adenoma

- Squamous cell carcinoma

- Large cell carcinoma

- Lymphoepithelial carcinoma

- Sialoblastoma

- Soft tissue tumors

- Hemangioma

- Hematolymphoid tumors

- Hodgkin lymphoma

- Diffuse large B-cell lymphoma

- Extranodal marginal zone B cell lymphoma

- Secondary tumors (i.e. a tumor which has metastasized to the salivary gland from a distant location)

Others, not included in the WHO classification above, include:

- Intraosseous (central) salivary gland tumors

- Hybrid tumors (i.e. a tumor displaying combined forms of histologic tumor types)

- Hybrid carcinoma

- Others

- Others

- Keratocystoma

- Sialolipoma

The signs and symptoms are similar to other malignant salivary gland tumours; however, it may have been preceded by an appreciable mass that was long-standing and did not appear to be growing.

Findings that suggest a malignant salivary gland tumour include rapid growth, facial weakness (due to facial nerve compression), pain, skin ulceration, fixation of the mastoid tip

and parasthesias.

Salivary gland tumours usually present as a lump or swelling in the affected gland which may or may not have been present for a long time. The lump may be accompanied by symptoms of duct blockage (e.g. xerostomia). Usually, in their early stages it is not possible to distinguish a benign tumour from a malignant one. One of the key differentiating symptoms of a malignant growth is nerve involvement. For example signs of facial nerve damage (e.g facial palsy) are associated with malignant parotid tumours. Facial pain, and paraesthesia are also very often associated with a malignant tumours. Other red flag symptoms which may suggest malignancy and warrant further investigation are fixation of the lump to the overlying skin, ulceration and induration of the mucosa.

The gland most likely affected is the parotid gland. In fact, it is the only tumor virtually restricted to the parotid gland. Though much less likely to occur than pleomorphic adenoma, Warthin's tumor is the second most common benign parotid tumor.

Warthin's tumor primarily affects older individuals (age 60–70 years). There is a slight male predilection according to recent studies. The tumor is slow growing, painless, and usually appears in the tail of the parotid gland near the angle of the mandible. In 5–14% of cases, Warthin's tumor is bilateral, but the two masses usually are at different times. Warthin's tumor is highly unlikely to become malignant.

About 25–50% of hepatic adenomas cause pain in the right upper quadrant or epigastric region of the abdomen. Since hepatic adenomas can be large (8–15 cm), patients may notice a palpable mass. However, hepatic adenomas are usually asymptomatic, and may be discovered incidentally on imaging ordered for some unrelated reason. Large hepatic adenomas have a tendency to rupture and bleed massively inside the abdomen. If not treated, there is a 30% risk of bleeding. Bleeding may lead to hypotension, tachycardia, and sweating (diaphoresis).

Carcinoma ex pleomorphic adenoma, abbreviated ca ex PA, is a type of cancer typically found in the parotid gland. It arises from the benign tumour pleomorphic adenoma.

Its prognosis depends on the stage. Early tumour have essentially a benign behaviour.

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 colorectal adenoma is a benign glandular tumor of the colon and the rectum. It is a precursor lesion of the colorectal adenocarcinoma (colon cancer).

Some morphological variants have been described:

- tubular adenoma

- tubulovillous adenoma

- villous adenoma

- sessile serrated adenoma (SSA)

See Hepatocellular adenoma. Hepatic adenomas are a rare benign tumour of the liver, which may present with hepatomegaly or other symptoms.

An adenoma of a parathyroid gland may secrete inappropriately high amounts of parathyroid hormone and thereby cause primary hyperparathyroidism.

Nipple adenomas may be felt as a lump under the nipple or areola. They may come to attention because of nipple pain, ulceration, swelling or discharge.

Pancreatic serous cystadenoma, also known as serous cystadenoma of the pancreas and serous microcystic adenoma, a benign tumour of pancreas. It is usually found in the head of the pancreas, and may be associated with von Hippel-Lindau syndrome.

In contrast to some of the other cyst-forming tumors of the pancreas (such as the intraductal papillary mucinous neoplasm and the mucinous cystic neoplasm), serous cystic neoplasms are almost always entirely benign. There are some exceptions; rare case reports have described isolated malignant serous cystadenocarcinomas. In addition, serous cystic neoplasms slowly grow, and if they grow large enough they can press on adjacent organs and cause symptoms.

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.

Hepatocellular adenoma (also known as hepatic adenoma or hepadenoma) is a rare, benign liver tumor. It most commonly occurs in people with elevated systemic levels of estrogen, classically in women taking estrogen-containing oral contraceptive medication.

Pathologists classify serous cystic neoplasms into two broad groups. Those that are benign, that have not spread to other organs, are designated "serous cystadenoma". Serous cystadenomas can be further sub-typed into microcystic, oligocystic (or macrocystic), solid, mixed serous-endocrine neoplasm, and VHL-associated serous cystic neoplasm. This latter classification scheme is useful because it highlights the range of appearances and the clinical associations of these neoplasms. Serous cystic neoplasms that have spread ("metastasized") to another organ are considered malignant and are designated "serous cystadenocarcinoma".

A sebaceous adenoma, a type of adenoma, a cutaneous condition characterized by a slow-growing tumor usually presenting as a pink, flesh-coloured, or yellow papule or nodule.

Sebaceous adenomas, in isolation, are not significant; however, they may be associated with Muir-Torre syndrome, a genetic condition that predisposes individuals to cancer. It is also linked to hereditary nonpolyposis colorectal cancer (Lynch Syndrome).

It is not the same as "adenoma sebaceum" by F. Balzer and P.E. Ménétrier (1885). The term "adenoma sebaceum" is a misnomer for "facial angiofibromas" associated with tuberous sclerosis complex.

Spiradenoma, also spiroma or eccrine spiradenoma, is a cutaneous condition that is typically characterized, clinically, as a solitary, deep-seated dermal nodule of approximately one centimeter, occurring on the ventral surface of the body. Spiradenoma lesions are benign sudoriferous tumors, and have also been described as cystic epitheliomas of the sweat glands.

The histological origin is controversial.

A nipple adenoma is a type of intraductal papilloma that arises within the lactiferous ducts that are located within the nipple.

Almost all thyroid adenomas are follicular adenomas. Follicular adenomas can be described as "cold", "warm" or "hot" depending on their level of function. Histopathologically, follicular adenomas can be classified according to their cellular architecture and relative amounts of cellularity and colloid into the following types:

- Fetal (microfollicular) - these have the potential for microinvasion. These consist of small, closely packed follicles lined with epithelium.

- colloid (macrofollicular) - these do "not" have any potential for microinvasion

- embryonal (atypical) - have the potential for microinvasion.

- Hürthle cell adenoma (oxyphil or oncocytic tumor) - have the potential for microinvasion.

- Hyalinizing trabecular adenoma

Papillary adenomas are very rare.

Hürthle cell adenoma is the benign analogue of Hürthle cell carcinoma. This adenoma is extremely rare; when it occurs, it usually occurs in women. Often the adenoma is harmless but is removed after detection because its future course cannot be trusted. This mass can be detected and removed before transformation and metastasis. The tumor is often detected by imaging such as ultrasound. The location and size of the tumor may cause pressure and pain to the patient. But often the tumor goes undetected. After detection, the mass is tested using an invasive fine-needle aspiration biopsy.

Hidradenoma (also known as acrospiroma, from "akral ""peripheral"" + spiroma ""epithelial tumor of sweat gland") refers to a benign adnexal tumor of the apical sweat gland. Another name for Hidradenoma is Cystadenoma and Hydrocystadenomas. These are 1–3 cm translucent blue cystic nodules.It usually presents as a single, small skin-colored lesion, and is considered distinct from the closely related poroma. Hidradenomas are often sub-classified based on subtle histologic differences, for example:

- clear-cell hidradenoma or acrospiroma

- nodular hidradenoma or acrospiroma

- solid-cystic hidradenoma

Discussion of sweat gland tumors can be difficult and confusing due to the complex classification and redundant terminology used to describe the same tumors. For example, acrospiroma and hidradenoma are synonymous, and sometimes the term "acrospiroma" is used to generally describe benign sweat gland tumors. In addition, a single lesion may contain a mixture of cell-types. There has also been a change in understanding about how tumors that were previously believed to strictly derive from specific sweat gland types may, in fact, derive from both eccrine "or" apocrine glands.

Hidradenomas are by definition benign, with malignant transformation very rare. When tumors show malignant characteristics, they are known as hidradenocarcinoma. Surgical excision is usually curative and local recurrences are rare, although malignant tumors may metastasize.

The symptoms may be similar to those classically associated with renal cell carcinoma, and may include polycythemia, abdominal pain, hematuria and a palpable mass. Mean age at onset is around 40 years with a range of 5 to 83 years and the mean size of the tumour is 5.5 cm with a range 0.3 to 15 cm (1). Polycythemia is more frequent in MA than in any other type of renal tumour. Of further relevance is that this tumour is more commonly calcified than any other kidney neoplasm. Surgery is curative and no other treatment is recommended. There is so far no evidence of metastases or local recurrence.