Papillary eccrine adenoma (also known as "tubular apocrine adenoma") is a cutaneous condition characterized by an uncommon benign sweat gland neoplasm that presents as a dermal nodule located primarily on the extremities of black patients.

A folliculosebaceous-apocrine hamartoma, also known as "follicular-apocrine hamartoma", is a benign proliferation of the folliculosebaceous-apocrine unit.

Syringomas can be found in association with other symptoms as part of a syndrome. Hailey-Hailey disease also known as familial benign chronic pemphigus is a blistering disease that can also include syringomas.

Several systemic syndromes have also been associated with syringoma including diabetes mellitus, down syndrome, Brooke-Spiegler, and Nicolau-Balus. Specifically, diabetes mellitus is strongly associated with clear cell syringoma consisting of nests of clear cells containing glycogen. It is thought that phosphorylase deficiency, resulting from elevated glucose levels seen in diabetes leads to an accumulation of glycogen in the skin and within the clear cells. The incidence of syringomas has been reported in up to 40 percent of people with Down syndrome and can be associated with a condition calcinosis cutis which requires prompt medical attention. Brooke-Spiegler syndrome is a rare autosomal dominant syndrome with cutaneous manifestations including syringomas and trichoepitheliomas. Nicolau-Balus is a rare autosomal dominant disorder consisting of atrophoderma vermiculata and syringomas.

There are a number of acquired causes of local gigantism. A body part can attain bigger size from causes as common as the following:

- inflammation, due to trauma or infection

- tumors like osteoid osteoma, melorheostosis, and lipofibromatous hamartoma

- Arteriovenous malformations occurring on a limb, before the closure of epiphyses in long bones

- Elephantiasis, which is quite common in south-east asia due to prevalence of filariasis.

- Still's disease

- amyloidosis

- acromegaly

The decision to observe or treat a nevus may depend on a number of factors, including cosmetic concerns, irritative symptoms (e.g., pruritus), ulceration, infection, and concern for potential malignancy.

Congenital causes include:

- Klippel Trenaunay Weber syndrome

- Maffucci syndrome

- macrodystrophia lipomatosa

- neurofibromatosis,

- lipoatrophic diabetes.

- Proteus syndrome, which by one theory accounts for the deformities of the Elephant Man

Mucinous nevus (also known as "Nevus mucinosus") is a rare cutaneous condition characterized by hamartoma that can be congenital or acquired.

Folliculosebaceous cystic hamartoma abbreviated as (FSCH) is a rare cutaneous hamartoma consisting of dilated folliculosebaceous units invested in mesenchymal elements. it typically affects adults, have a predilection for the central face or scalp, with less than 1.5 cm dimension. Clinically, the lesions are asymptomatic, rubbery to firm in consistency, and usually occur on or above the neck in (> 90%) of cases, Histopathologically, FSCH shares several similar features to sebaceous trichofolliculoma, but it is usually possible to differentiate these two tumors.

These nevi represent excess growth of blood vessels, including capillaries.

- Nevus simplex (also known as a stork bite, salmon patch, or Nevus flammeus neonatorum)

Lipomatosis is believed to be a hereditary condition in which multiple lipomas are present on the body.

Adiposis dolorosa (Dercum disease) is a rare condition involving multiple painful lipomas, swelling, and fatigue. Early studies mentioned prevalence in obese postmenopausal women. However, current literature demonstrates that Dercum disease is present in more women than men of all body types; the average age for diagnosis is 35 years.

Benign symmetric lipomatosis (Madelung disease) is another condition involving lipomatosis. It nearly always appears in middle-aged males after many years of alcoholism. But, non-alcoholics and females can also be affected.

A basaloid follicular hamartoma is a cutaneous condition characterized as distinctive benign adnexal tumor that has several described variants.

A poroma is a benign skin tumor derived from sweat glands. Although the original term "poroma "was initially used to describe a tumor derived from the ductal epithelium of eccrine sweat glands, the term is used in general reference to tumors derived from ductal portions of both eccrine and apocrine sweat glands. Specific sub-types are primarily defined by location of tumor, and include:

- eccrine poroma

- hidroacanthoma simplex (intraepithelial poroma)

- dermal duct tumor (intradermal poroma)

- syringoacanthoma

- syringofibroadenoma

- poroid hidradenoma ("disputed as different family")

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.

In dermatologic pathology, a dermal cylindroma, also dermal eccrine cylindroma or Cutaneous Cylindroma) and (less specifically) cylindroma, is a benign adnexal tumor, which occurs on the scalp and forehead.when multiple Cylindroma-Show Hat like configration.

Multiple cylindromas may grow together in a "hat-like" configuration, sometimes referred to as a turban tumor. Cylindromas are uncommon dysplasias of skin appendages.

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).

The tendency to develop a lipoma is not necessarily hereditary, although hereditary conditions such as familial multiple lipomatosis might include lipoma development. Genetic studies in mice have shown a correlation between the "HMG I-C" gene (previously identified as a gene related to obesity) and lipoma development. These studies support prior epidemiologic data in humans showing a correlation between "HMG I-C" and mesenchymal tumors.

Cases have been reported where minor injuries are alleged to have triggered the growth of a lipoma, called "post-traumatic lipomas." However, the link between trauma and the development of lipomas is controversial.

A variant of eccrine spiradenoma which can be multiple on the scalp and can coalesce to form a 'Turban' tumour. In pathology, a cylindroma is a tumour with nests of cells that resemble a cylinder in cross section.

Types include:

- Dermal eccrine cylindroma, a benign tumour of the skin

- Adenoid cystic carcinoma, a malignant tumour of the salivary gland

Syringomas are harmless eccrine sweat duct tumors, typically found clustered on eyelids, although they may also be found in the armpits, abdomen, chest, neck, scalp or groin area including genitals in a symmetric pattern. They are skin-colored or yellowish firm, rounded bumps, 1–3 mm in diameter, and may be confused with xanthoma, milia, hidrocystoma, trichoepithelioma, and xanthelasma. They are more common in women and are most commonly found in middle-aged Asian women. While they can present at any time in life, they typically present during adolescence. They are usually not associated with any other symptoms although can sometimes cause itchiness or irritation.

Congenital smooth muscle hamartoma is typically a skin colored or lightly pigmented patch or plaque with hypertrichosis.

Fibrous hamartoma of infancy is a rapidly growing, painless, ill-defined subcutaneous or intradermal nodule that is generally solitary and less than 5 cm in size, though, rarely, multiple lesions occur synchronously.

By 1999, there were 12 reported cases.

The majority of patients are less than 2 years old, with 25% of cases being congenital. Possible locations include the trunk and limbs; usually the upper arm or shoulder. Local excision is the treatment of choice, but it may recur locally.

Because Cowden syndrome can be difficult to diagnose, the exact prevalence is unknown; however, it probably occurs in at least 1 in 200,000 people.

A 2010 review of 211 patients (21 from one center, and the remaining 190 from the external literature) studied the risks for cancer and Lhermitte-Duclos disease in Cowden syndrome patients.

The cumulative lifetime (age 70 years) risks were 89% for any cancer diagnosis (95% confidence interval (CI) = 80%,95%), breast cancer [female] 81% (CI = 66%,90%), LDD 32% (CI = 19%,49%), thyroid cancer 21% (CI = 14%,29%), endometrial cancer 19% (CI = 10%,32%) and renal cancer 15% (CI = 6%,32%). A previously unreported increased lifetime risk for colorectal cancer was identified (16%, CI = 8%,24%). Male CS patients had fewer cancers diagnosed than female patients and often had cancers not classically associated with CS.

Hair follicle nevus (also known as a "Vellus hamartoma") is a cutaneous condition that presents as a small papule from which fine hairs protrude evenly from the surface.

Hamartomas, while generally benign, can cause problems due to their location. For example, when located on the skin, especially on the face or neck, they can be very disfiguring. Cases have been reported of hamartomas the size of a small orange. They may obstruct practically any organ in the body, such as the colon, eye, etc. They are particularly likely to cause major health issues when located in the hypothalamus, kidneys, lips, or spleen. They can be removed surgically if necessary, and are not likely to recur. Prognosis will depend upon the location and size of the lesion, as well as the overall health of the patient.

Syringofibroadenoma (also known as "acrosyringeal nevus of Weedon and Lewis") is a cutaneous condition characterized by a hyperkeratotic nodule or plaque involving the extremities.

It is considered of eccrine origin.

Eccrine angiomatous hamartoma usually appear as a solitary nodular lesion on the acral areas of the extremities, particularly the palms and soles.