Generalized trichoepitheliomas are characterized histologically by replacement of the hair follicles by trichoepithelioma-like epithelial proliferations associated with hyperplastic sebaceous glands.

Hidrocystoma (also known as cystadenoma, a Moll's gland cyst, and a sudoriferous cyst) is an adenoma of the sweat glands.

Hidrocystomas are cysts of sweat ducts, usually on the eyelids. They are not tumours (a similar-sounding lesion called hidroadenoma is a benign tumour).

There are three types of "sweat" glands: True sweat glands or eccrine glands;

sebaceous glands, which have an oily secretion around hair follicles; and apocrine glands which have more oily product than eccrine glands and are found on the face, armpit, and groin.

Hidrocystomas usually arise from apocrine glands. They are also called Cysts of Moll or sudoriferous cysts. There may be a type of hidroadenoma that arises from eccrine glands, but these are uncommon.

Other related conditions on the eyelids include chalazion ( a granulomatous reaction to sebaceous glands on the eyelid), lacrimal duct cysts (cysts related to tear ducts) and nasolacrimal duct cysts (the nasolacrimal duct drains tears into the nose via a punctum on the lower eyelid).

Sebaceous hyperplasia is a disorder of the sebaceous glands in which they become enlarged, producing flesh-colored or yellowish, shiny, often umbilicated bumps on the face. Newly formed nodules often swell with sweating (which is pathognomonic for the condition), but this diminishes over time.

Sebaceous glands are glands located within the skin and are responsible for secreting an oily substance named sebum. They are commonly associated with hair follicles but they can be found in hairless regions of the skin as well. Their secretion lubricates the skin, protecting it from drying out or becoming irritated.

Sebaceous hyperplasia generally affects newborns as well as middle-aged to elderly adults. The symptoms of this condition are 1–5 mm papules on the skin, mainly on the forehead, nose and cheeks, and seborrheic facial skin. The papules may be cauliflower-shaped. In infants, acne is sometimes associated with sebaceous hyperplasia.

Benign lymphoepithelial lesion is most likely to occur in adults around 50 years of age. There is a predilection for gender with 60–80% being female. The gland affected has a diffuse swelling. The swelling can be asymptomatic, but mild pain can also be associated. There is a preponderance of this disease in those who suffer from HIV infection.

Most cases of benign lymphoepithelial lesions appear in conjunction with Sjögren's syndrome. When Sjögren's syndrome is present, the swelling is usually bilateral. Otherwise, the affected glands are usually only on one side of the body.

In many cases, a biopsy is needed to distinguish benign lymphoepithelial lesions from sialadenosis (sialosis).

In the case of endometrial hyperplasia usually a Pap smear is done, also a biopsy during the pelvic examination, may be done of the individuals endometrial tissue. You may want to consult your doctor for further examination.

In regards to Cushing's disease, the diagnosis of salivary cortisol in an elevated level around "late-night" is a way to detect it in many patients.

In 80% of cases, the parotid gland is affected. Lacrimal glands are also affected.

Blepharophyma is chronic swelling of eyelids, mainly due to sebaceous gland hyperplasia.

Hyperplasia may be due to any number of causes, including increased demand (for example, proliferation of basal layer of epidermis to compensate skin loss), chronic inflammatory response, hormonal dysfunctions, or compensation for damage or disease elsewhere. Hyperplasia may be harmless and occur on a particular tissue. An example of a normal hyperplastic response would be the growth and multiplication of milk-secreting glandular cells in the breast as a response to pregnancy, thus preparing for future breast feeding.

Perhaps the most interesting and potent effect IGF has on the human body is its ability to cause hyperplasia, which is an actual splitting of cells. By contrast, hypertrophy is what occurs, for example, to skeletal muscle cells during weight training and steroid use and is simply an increase in the size of the cells. With IGF use, one is able to cause hyperplasia which actually increases the number of muscle cells present in the tissue. Weight training with or without anabolic steroid use enables these new cells to mature in size and strength. It is theorized that hyperplasia may also be induced through specific power output training for athletic performance, thus increasing the number of muscle fibers instead of increasing the size of a single fiber.

On the shaft of the penis, Fordyce spots are more visible when the skin is stretched, and may only be noticeable during an erection.

The spots can also appear on the skin of the scrotum.

Oral Fordyce granules appear as rice-like granules, white or yellow-white in color. They are painless papules (small bumps), about 1–3 mm in greatest dimension. The most common site is along the line between the vermilion border and the oral mucosa of the upper lip, or on the buccal mucosa (inside the cheeks) in the commissural region, often bilaterally. They may also occur on the mandibular retromolar pad and tonsillar areas, but any oral surface may be involved. There is no surrounding mucosal change. Some patients will have hundreds of granules while most have only one or two.

Occasionally, several adjacent glands will coalesce into a larger cauliflower-like cluster similar to sebaceous hyperplasia of the skin. In such an instance, it may be difficult to determine whether or not to diagnose the lesion as sebaceous hyperplasia or sebaceous adenoma. The distinction may be moot because both entities have the same treatment, although the adenoma has a greater growth potential. Sebaceous carcinoma of the oral cavity has been reported, presumably arising from Fordyce granules or hyperplastic foci of sebaceous glands.

In some persons with Fordyce spots, the glands express a thick, chalky discharge when squeezed.

Sebaceous glands are normal structures of the skin but may also be found ectopically in the mouth, where they are referred to as "oral Fordyce granules" or ectopic sebaceous glands.

On the foreskin they are called Tyson's glands, not to be confused with hirsuties coronae glandis.

When they appear on the penis, they are also called "penile sebaceous glands".

When seen as a streak of individual glands along the interface between the skin of the lip and the vermilion border, the terms Fox–Fordyce disease and Fordyce's condition have been used.

Salivary gland diseases (SGD) are multiple and varied in cause.

There are 3 paired major salivary glands in humans (the parotid gland, the submandibular gland, and the sublingual gland), as well as about 800-1000 minor salivary glands in the oral mucosa of the mouth. The parotid gland is located in front of the ear, and it secretes its mostly serous saliva via the parotid duct (Stenson duct) into the mouth, usually opening roughly opposite the maxillary second molar. The submandibular gland is located medial to the angle of the mandible, and it drains its mixture of serous and mucous saliva via the submandibular duct (Wharton duct) into the mouth, usually opening in a punctum located in the floor of mouth. The sublingual gland is located below the tongue, in the floor of the mouth. It drains its mostly mucous saliva into the mouth via about 8-20 ducts which open along the plica sublingualis (a fold of tissue under the tongue).

The function of the salivary glands is to secrete saliva, which has a lubricating function, which protects the oral mucosa of the mouth during eating and speaking. Saliva also contains digestive enzymes (e.g. salivary amylase) and has antimicrobial action and acts as a buffer. Persons with reduced salivary flow or hyposalivation often suffer from dry mouth or xerostomia, which can result in severe dental caries (tooth decay) as a result of the loss of the protective effects of saliva.

Various examples of disorders affecting the salivary glands are listed below. Some are more common than others, and they are considered according to a surgical sieve, but this list is not exhaustive. Sialadenitis is inflammation of a salivary gland, usually caused by infections, although there are other less common causes of inflammation such as irradiation, allergic reactions or trauma.

Ectopic salivary gland tissue which is located in sites other than the normal location is variously described as aberrant, accessory, ectopic, heterotopic or salivary gland choristoma.

Congenital disorders of the salivary glands are rare, but may include:

- Aplasia

- Atresia

- Ectopic salivary gland tissue

- Stafne defect - an uncommon condition which some consider to be an anatomic variant rather than a true disease. It is thought to be created by an ectopic portion of salivary gland tissue which causes the bone of the mandible to remodel around the tissue, creating an apparent cyst like radiolucent area on radiographs. Classically, this lesion is discovered as a chance finding, since it causes no symptoms. It appears below the inferior alveolar nerve canal in the posterior region of the mandible.

Adnexal and skin appendage neoplasms is a group of tumors which develop in the adnexal skin structures such as the sweat and sebaceous glands. An example is the hidrocystoma.

An "accessory salivary gland" is ectopic salivary gland tissue with a salivary gland duct system. The most common location of accessory salivary gland tissue is an extra major salivary gland in front of the parotid gland. It is typically about 3 cm or less in size, and drains into the parotid duct via a single tributary. Accessory parotid tissue is found in 21-56% of adults. Any disease process which affects the salivary glands, including cancer, may also occur within an accessory salivary gland tissue.

A pituitary disease is a disorder primarily affecting the pituitary gland.

The main disorders involving the pituitary gland are:

Overproduction or underproduction of a pituitary hormone will affect the respective end-organ. For example, insufficient production (hyposecretion) of thyroid stimulating hormone (TSH) in the pituitary gland will cause hypothyroidism, while overproduction (hypersecretion) of TSH will cause hyperthyroidism. Thyroidisms caused by the pituitary gland are less common though, accounting for less than 10% of all hypothyroidism cases and much less than 1% of hyperthyroidism cases.

The inflammatory lesions in Küttner's tumor may occur on one side (unilateral) or both sides (bilateral), predominantly involving the submandibular gland, but is also known to occur in other major and minor salivary glands, including the parotid gland.

Overall, salivary gland tumors are relatively rare, with approximately 2.5–3 cases per 100,000 people per year seen in the Western world; however, salivary gland malignancies account for 3–5% of all head and neck cancers. However, salivary tumors show a great deal of morphological diversity, as well as variations in the nature of the lesion (malignant vs. benign): approximately 20% to 25% of parotid tumors, 35% to 40% of submandibular tumors, and more than 90% of sublingual gland tumors are malignant. This situation underscores the diagnostic challenges in respect of Küttner's tumor; despite being benign, this condition mimics the clinical appearance of malignancy in the salivary gland.

The swollen masses of Küttner's tumor are generally painful, and patients are advised surgical resection (known as 'sialadenectomy') of a part or whole of the glandular tissue upon suspicion of possible malignancy. It is only upon post-surgical histopathology of the excised mass that the diagnosis of Küttner's tumor is definitively made.

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.

Nevus sebaceus or sebaceous nevus (the first term is its Latin name, the second term is its name in English; also known as an "organoid nevus" and "nevus sebaceus of Jadassohn") is a congenital, hairless plaque that typically occurs on the face or scalp. Such nevi are present at birth, or early childhood, affecting males and females of all races equally. The condition is named for an overgrowth of sebaceous glands in the area of the nevus.

Skin growths such as benign tumors and basal cell carcinoma can arise in sebaceous nevi, usually in adulthood. Rarely, sebaceous nevi can give rise to sebaceous carcinoma. However, the rate of such malignancies is now known to be less than had been estimated. For this reason, excision is no longer automatically recommended.

Sebaceous lymphadenoma is a tissue diagnosis, e.g. salivary gland biopsy.

It may be confused with a number of benign and malignant neoplasms, including Warthin tumour, mucoepidermoid carcinoma and sebaceous lymphadenocarcinoma.

Chronic sclerosing sialadenitis is a chronic (long-lasting) inflammatory condition affecting the salivary gland. Relatively rare in occurrence, this condition is benign, but presents as hard, indurated and enlarged masses that are clinically indistinguishable from salivary gland neoplasms or tumors. It is now regarded as a manifestation of IgG4-related disease.

Involvement of the submandibular glands is also known as Küttner's tumor, named after Hermann Küttner (1870–1932), a German Oral and Maxillofacial Surgeon, who reported four cases of submandibular gland lesions for the first time in 1896.

The treatment is simple excision and exclusion of a malignant neoplasm.

Rhinophyma is a slowly progressive condition due to hypertrophy of the sebaceous glands of the tip of the nose often seen in cases of long-standing acne rosacea; it is not a neoplasm. It presents as a pink, lobulated mass over the nose with superficial vascular dilation; it mostly affects men past middle age. Patients seek advice because of the perceived unsightly appearance of the enlargement, or obstruction in breathing and vision.

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.

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