Seborrheic keratosis | |
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Other names | Seborrheic verruca, basal cell papilloma, senile wart [1] [2] : 767 [3] : 637 |
Multiple seborrheic keratoses on the back of a patient with Leser–Trélat sign | |
Specialty | Dermatology |
Diagnostic method | Based on clinical examination, skin biopsy |
Treatment | Electrodesiccation and curettage, cryotherapy |
A seborrheic keratosis is a non-cancerous (benign) skin tumour that originates from cells, namely keratinocytes, in the outer layer of the skin called the epidermis. Like liver spots, seborrheic keratoses are seen more often as people age. [4]
The tumours (also called lesions) appear in various colours, from light tan to black. They are round or oval, feel flat or slightly elevated, like the scab from a healing wound, and range in size from very small to more than 2.5 centimetres (1 in) across. [5] They are often associated with other skin conditions, including basal cell carcinoma. [6] Rarely, seborrheic keratosis and basal cell carcinoma occur at the same location. At clinical examination, the differential diagnosis include a wart and melanoma. [4] Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts", because they resemble warts, but strictly speaking, the term "warts" refers to lesions that are caused by the human papillomavirus. [7]
The cause of seborrheic keratosis is not known. The only definitive association is that its prevalence increases with age. [4]
Visual diagnosis is made by the "stuck on" appearance, horny pearls or cysts embedded in the structure. Darkly pigmented lesions can be challenging to distinguish from nodular melanomas. [8] Furthermore, thin seborrheic keratoses on facial skin can be very difficult to differentiate from lentigo maligna even with dermatoscopy. Clinically, epidermal nevi are similar to seborrheic keratoses in appearance. Epidermal nevi are usually present at or near birth. Condylomas and warts can clinically resemble seborrheic keratoses, and dermatoscopy can be helpful to differentiate them. On the penis and genital skin, condylomas and seborrheic keratoses can be difficult to differentiate, even on biopsy.[ citation needed ]
A study examining over 4,000 biopsied skin lesions identified clinically as seborrheic keratoses showed 3.1% were malignancies. Two-thirds of those were squamous cell carcinoma. [9] To date, the gold standard in the diagnosis of seborrheic keratosis is represented by the histolopathologic analysis of a skin biopsy. [10]
Seborrheic keratoses may be divided into the following types: [2] [11] [12]
Subtype (and alternative names) | Characteristics | Image |
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Common seborrheic keratosis (basal cell papilloma, solid seborrheic keratosis) | Dull or lackluster surface. [2] : 769 | |
Reticulated seborrheic keratosis (adenoid seborrheic keratosis) | Dull or lackluster surface, and with keratin cysts seen histologically. [2] : 769 | |
Stucco keratosis (deratosis alba, [13] digitate seborrheic keratosis, hyperkeratotic seborrheic keratosis, serrated seborrheic keratosis, verrucous seborrheic keratosis) | Common. Dull or lackluster surface, and with church-spire-like projections of epidermal cells around collagen seen histologically. [2] [3] Stucco keratoses are often light brown to off-white, and are no larger than a few millimeters in diameter. They are often found on the distal tibia, ankle, and foot. [12] | |
Clonal seborrheic keratosis | Dull or lackluster surface, and with round, loosely packed nests of cells seen histologically. [2] : 769 | |
Irritated seborrheic keratosis (inflamed seborrheic keratosis, basosquamous cell acanthoma) | Dull or lackluster surface. [2] : 769 | |
Seborrheic keratosis with squamous atypia | Dull or lackluster surface, and with round, loosely packed nests of cells seen histologically. [2] : 770 | |
Melanoacanthoma (pigmented seborrheic keratosis) | Dull or lackluster surface. [2] : 770 [3] : 687 It involves a proliferation of keratinocytes and melanocytes. [14] | |
Inverted follicular keratosis [notes 1] | Asymptomatic, firm, white–tan to pink papules [13] Microscopically it is characterized as a well-circumscribed inverted acanthotic squamous proliferation containing squamous eddies and without significant atypia. [15] |
Dermatosis papulosa nigra (DPN) is a condition of many small, benign skin lesions on the face, a condition generally presenting on darker-skinned individuals. [3] : 638–9 DPN is extremely common, affecting up to 30% of black people in the United States. [16]
Medical reasons for removing seborrheic keratoses include irritation and bleeding. They may also be removed for cosmetic reasons. [17] [4] Generally, lesions can be treated with electrodesiccation and curettage, or cryosurgery. When correctly performed, removal of seborrheic keratoses will not cause much visible scarring. [18]
Seborrheic keratosis is the most common benign skin tumor. Incidence increases with age. There is less prevalence in people with darker skin. [19] In large-cohort studies, all patients aged 50 and older had at least one seborrheic keratosis. [20] Onset is usually in middle age, although they are common in younger patients too, as they are found in 12% of 15-year-olds to 25-year-olds, which makes the term "senile keratosis" a misnomer. [21]
A melanocytic nevus is usually a noncancerous condition of pigment-producing skin cells. It is a type of melanocytic tumor that contains nevus cells. Some sources equate the term mole with "melanocytic nevus", but there are also sources that equate the term mole with any nevus form.
Cutaneous squamous-cell carcinoma (cSCC), or squamous-cell carcinoma of the skin, also known as squamous-cell skin cancer, is, with basal-cell carcinoma and melanoma, one of the three principal types of skin cancer. cSCC typically presents as a hard lump with a scaly top layer, but it may instead form an ulcer. Onset often occurs over a period of months. Cutaneous squamous-cell carcinoma is more likely to spread to distant areas than basal cell cancer. When confined to the outermost layer of the skin, a pre-invasive, or in situ, form of cSCC is known as Bowen's disease.
Basal-cell carcinoma (BCC), also known as basal-cell cancer, basalioma or rodent ulcer, is the most common type of skin cancer. It often appears as a painless raised area of skin, which may be shiny with small blood vessels running over it. It may also present as a raised area with ulceration. Basal-cell cancer grows slowly and can damage the tissue around it, but it is unlikely to spread to distant areas or result in death.
Lichen planus (LP) is a chronic inflammatory and autoimmune disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, but is named for its appearance. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale, commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. The hue may be gray-brown in people with darker skin. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.
A dermatofibroma, or benign fibrous histiocytomas, is a benign nodule in the skin, typically on the legs, elbows or chest of an adult. It is usually painless.
Actinic keratosis (AK), sometimes called solar keratosis or senile keratosis, is a pre-cancerous area of thick, scaly, or crusty skin. Actinic keratosis is a disorder of epidermal keratinocytes that is induced by ultraviolet (UV) light exposure. These growths are more common in fair-skinned people and those who are frequently in the sun. They are believed to form when skin gets damaged by UV radiation from the sun or indoor tanning beds, usually over the course of decades. Given their pre-cancerous nature, if left untreated, they may turn into a type of skin cancer called squamous cell carcinoma. Untreated lesions have up to a 20% risk of progression to squamous cell carcinoma, so treatment by a dermatologist is recommended.
Dermatopathology is a joint subspecialty of dermatology and pathology or surgical pathology that focuses on the study of cutaneous diseases at a microscopic and molecular level. It also encompasses analyses of the potential causes of skin diseases at a basic level. Dermatopathologists work in close association with clinical dermatologists, with many possessing further clinical training in dermatology. The field was founded by German dermatologist and physician Gustav Simon, who published the first textbook on dermatopathology, 'Skin Diseases Illustrated by Anatomical Investigations', in 1848.
A dysplastic nevus or atypical mole is a nevus (mole) whose appearance is different from that of common moles. In 1992, the NIH recommended that the term "dysplastic nevus" be avoided in favor of the term "atypical mole". An atypical mole may also be referred to as an atypical melanocytic nevus, atypical nevus, B-K mole, Clark's nevus, dysplastic melanocytic nevus, or nevus with architectural disorder.
Lentigo maligna melanoma is a melanoma that has evolved from a lentigo maligna, as seen as a lentigo maligna with melanoma cells invading below the boundaries of the epidermis. They are usually found on chronically sun damaged skin such as the face and the forearms of the elderly.
Lentigo maligna is where melanocyte cells have become malignant and grow continuously along the stratum basale of the skin, but have not invaded below the epidermis. Lentigo maligna is not the same as lentigo maligna melanoma, as detailed below. It typically progresses very slowly and can remain in a non-invasive form for years.
Dermatoscopy also known as dermoscopy or epiluminescence microscopy, is the examination of skin lesions with a dermatoscope. It is a tool similar to a camera to allow for inspection of skin lesions unobstructed by skin surface reflections. The dermatoscope consists of a magnifier, a light source, a transparent plate and sometimes a liquid medium between the instrument and the skin. The dermatoscope is often handheld, although there are stationary cameras allowing the capture of whole body images in a single shot. When the images or video clips are digitally captured or processed, the instrument can be referred to as a digital epiluminescence dermatoscope. The image is then analyzed automatically and given a score indicating how dangerous it is. This technique is useful to dermatologists and skin cancer practitioners in distinguishing benign from malignant (cancerous) lesions, especially in the diagnosis of melanoma.
Dermatosis papulosa nigra (DPN) is a condition of many small, benign skin lesions on the face, a condition generally presenting on dark-skinned individuals. DPN is extremely common, affecting up to 30% of Black people in the US. From a histological perspective, DPN resembles seborrheic keratoses. The condition may be cosmetically undesirable to some.
Epidermodysplasia verruciformis (EV) is a skin condition characterised by warty skin lesions. It results from an abnormal susceptibility to HPV infection (HPV) and is associated with a high lifetime risk of squamous cell carcinomas in skin. It generally presents with scaly spots and small bumps particularly on the hands, feet, face and neck; typically beginning in childhood or in a young adult. The bumps tend to be flat, grow in number and then merge to form plaques. On the trunk, it typically appears like pityriasis versicolor; lesions there being slightly scaly and tan, brown, red or looking pale. On the elbows, it may appear like psoriasis. On the forehead, neck and trunk, the lesions may appear like seborrheic keratosis.
Skin biopsy is a biopsy technique in which a skin lesion is removed to be sent to a pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. It is commonly performed by dermatologists. Skin biopsies are also done by family physicians, internists, surgeons, and other specialties. However, performed incorrectly, and without appropriate clinical information, a pathologist's interpretation of a skin biopsy can be severely limited, and therefore doctors and patients may forgo traditional biopsy techniques and instead choose Mohs surgery.
Cutaneous horns, also known by the Latin name cornu cutaneum, are unusual keratinous skin tumors with the appearance of horns, or sometimes of wood or coral. Formally, this is a clinical diagnosis for a "conical projection above the surface of the skin." They are usually small and localized but can, in very rare cases, be much larger. Although often benign, they can also be malignant or premalignant.
Warty dyskeratoma, also known as an Isolated dyskeratosis follicularis, is a benign epidermal proliferation with distinctive histologic findings that may mimic invasive squamous cell carcinoma and commonly manifests as an umbilicated lesion with a keratotic plug, WD have some histopathologic similarities to viral warts but it's not caused by HPV and the majority of these lesions display overall histopathologic features consistent with a follicular adnexal neoplasm. Usually limited to the head, neck, scalp or face and vulva. Lesions are generally solitary and sporadic and may be associated with a follicular unit. Oral involvement, particularly the hard palate, and genital involvement have been reported. it can also be thought of as one of the manifestations of focal acantholytic dyskeratosis, an epidermal reaction pattern that can be seen in several disorders, including Darier's disease and Grover's disease. But the main Difference between Darier disease and Warty dyskeratoma, is that Darier disease inherited dermatosis consisting of multiple keratotic papules on the face, trunk, and extremities, while WD occurs as an isolated, noninherited, single keratotic nodule mainly confined to the head and neck as mentioned earlier.
Clear cell acanthoma is a benign clinical and histological lesion initially described as neoplastic, which some authors now regard as a reactive dermatosis. It usually presents as a moist solitary firm, brown-red, well-circumscribed, 5 mm to 2 cm nodule or plaque on the lower extremities of middle-aged to elderly individuals. The lesion has a crusted, scaly peripheral collarette and vascular puncta on the surface. It is characterized by slow growth, and may persist for years. The clinical differential diagnosis includes: dermatofibroma, inflamed seborrheic keratosis, pyogenic granuloma, basal-cell carcinoma, squamous cell carcinoma, verruca vulgaris, psoriatic plaque, and melanoma.
Poromas are rare, benign, cutaneous adnexal tumors. Cutaneous adnexal tumors are a group of skin tumors consisting of tissues that have differentiated towards one or more of the four primary adnexal structures found in normal skin: hair follicles, sebaceous sweat glands, apocrine sweat glands, and eccrine sweat glands. Poromas are eccrine or apocrine sweat gland tumors derived from the cells in the terminal portion of these glands' ducts. This part of the sweat gland duct is termed the acrosyringium and had led to grouping poromas in the acrospiroma class of skin tumors. Here, poromas are regarded as distinct sweat gland tumors that differ from other sweat gland tumors by their characteristic clinical presentations, microscopic histopathology, and the genetic mutations that their neoplastic cells have recently been found to carry.
A nevoid melanoma is a malignant neoplastic lesion of the skin. It is a type of melanoma, the most dangerous form of skin cancer. Nevoid melanomas are clinically significant because they are difficult to distinguish from a benign nevus of the skin, which requires no treatment and is common on most individuals. Nevoid morphologies represent up to 3% of all cases of melanoma.
§Seborrheic Keratosis: ... Differentiating between seborrheic keratoses and melanomas is a challenge. Both have variable dark colors, the potential for large size, and irregularity.