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any horny growth, such as a wart or callosity.
actinic keratosis a sharply outlined wartlike or keratotic growth, which may develop into a cutaneous horn, and may become malignant; it usually occurs in the middle aged or elderly and is due to excessive exposure to the sun. Called also senile or solar keratosis. (See Atlas 3, Part F).
keratosis follicula´ris a slowly progressive autosomal dominant disorder of keratinization characterized by pinkish to tan or skin-colored papules on the seborrheic areas of the body that coalesce to form plaques, which may become crusted and secondarily infected; over time, the lesions may become darker and may fuse to form papillomatous and warty malodorous growths. Called also Darier's disease and Darier-White disease.
keratosis palma´ris et planta´ris palmoplantar keratoderma.
keratosis pharyn´gea horny projections from the tonsils and pharyngeal walls. Called also pharyngokeratosis.
keratosis pila´ris hyperkeratosis limited to the hair follicles.
keratosis puncta´ta a hereditary hyperkeratosis in which the lesions are localized in multiple points on the palms and soles.
seborrheic keratosis (keratosis seborrhe´ica) a benign, noninvasive tumor of epidermal origin, marked by numerous yellow or brown, sharply marginated, oval, raised lesions.
senile keratosis (solar keratosis) actinic keratosis.


, pl.


(ker'ă-tō'sis, -sēz),
Any lesion on the epidermis marked by the presence of circumscribed overgrowths of the horny layer.
[kerato- + G. -osis, condition]


/ker·a·to·sis/ (ker″ah-to´sis) pl. kerato´ses   any horny growth, such as a wart or callosity.keratot´ic
actinic keratosis  a sharply outlined verrucous or keratotic growth, which may develop into a cutaneous horn, and may become malignant; it usually occurs in the middle-aged or elderly and is due to excessive exposure to the sun.
keratosis blennorrha´gica  keratoderma blennorrhagicum.
keratosis follicula´ris  a hereditary form marked by areas of crusting, itching, verrucous papular growths which may fuse to form papillomatous and warty malodorous growths.
inverted follicular keratosis  a benign usually solitary epithelial tumor originating in a hair follicle and occurring as a flesh-colored nodule or papule.
keratosis palma´ris et planta´ris  palmoplantar keratoderma.
keratosis pharyn´gea  that characterized by horny projections from the tonsils and the orifices of the lymph follicles in the pharyngeal walls.
keratosis pila´ris  hyperkeratosis limited to the hair follicles.
keratosis puncta´ta  a hereditary hyperkeratosis in which the lesions are localized in multiple points on the palms and soles.
seborrheic keratosis , keratosis seborrhe´ica a benign tumor of epidermal origin, marked by soft friable plaques with slight to intense pigmentation, most often on the face, trunk, and limbs.
senile keratosis , solar keratosis actinic k.


n. pl. kerato·ses (-sēz)
Excessive growth of horny tissue of the skin.

ker′a·tot′ic (-tŏt′ĭk) adj.


Etymology: Gk, keras + osis, condition
any skin lesion in which there is overgrowth and thickening of the cornified epithelium. Approximately 20% of these skin lesions develop into squamous cell carcinoma. Prevention includes the use of sunscreen and the avoidance of drugs known to cause photosensitivity reactions. Kinds of keratosis include actinic keratosis, keratosis pilaris, keratosis senilis, and seborrheic keratosis. keratotic, adj.


Dermatology A condition characterized by ↑ keratin production See Actinic keratosis, Seborrheic keratosis, Stucco keratosis.


, pl. keratoses (ker'ă-tō'sis, -sēz)
Any lesion on the epidermis marked by the presence of circumscribed overgrowths of the horny layer.
[kerato- + G. -osis, condition]


(ker?a-to'sis) (-to'sez?) plural.keratoses [ kerato- + -osis]
1. Growth of the horny layer of the skin; a callus, callosity, or keratoma.
2. Any condition of the skin characterized by the formation of horny growths or excessive development of the horny growth. keratotic (?a-tot'ik), adjective Synonym: keratoma
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ACTINIC KERATOSIS: Actinic skin damage on forehead and scalp

actinic keratosis

Abbreviation: AK
A rough, sandpaper-textured, premalignant macule or papule caused by excess exposure to ultraviolet light. AKs often appear on facial skin (such as near the eyes, on the nose, on the ears, or the lips) and the parts of the body that receive the most sunlight exposure. Prevention of AKs depends on limiting one's exposure to sunlight, beginning in childhood and continuing throughout life. See: illustration


Liquid nitrogen destroys these lesions and prevents them from progressing to other cancers of the skin.

Synonym: solar keratosis See: sunscreen

keratosis follicularis

Darier's disease.

keratosis nigricans

Acanthosis nigricans.

oral keratosis

Keratinization of the mucosa of the mouth to an unusual extent, or in locations normally not keratinized, as a result of an inherited autosomal dominant gene or the more common effect of tobacco and other carcinogens.

keratosis palmaris et plantaris

A congenital abnormality of the palms and soles, characterized by a dense thickening of the keratin layer in these regions.

keratosis pharyngis

Horny projections from the pharyngeal tonsils and adjacent lymphoid tissue.

keratosis pilaris

Chronic inflammatory disorder of area surrounding the hair follicles. It is often found in patients with atopic dermatitis. Synonym: lichen pilaris; lichen spinulosus


The disorder is characterized by an accumulation of horny material at follicular orifices of persons with rough, dry skin. It is most pronounced in winter on lateral aspects of thighs and upper arms with possible extension to legs, forearms, and scalp.


There is no specific therapy, but keratolytic lotions may be of some value.

keratosis punctata

Discrete horny projections from the sweat pores of the palms and soles.
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seborrheic keratosis

A benign skin tumor that may be pigmented. It is composed of immature epithelial cells and is quite common in older adults. Its etiology is unknown.


Keratoid, nevoid, acanthoid, or verrucose types occur in older adults and in those with long-standing dry seborrhea, on the face, scalp, interscapular or sternal regions, and backs of the hands. The yellow, gray, or brown sharply circumscribed lesions are covered with a firmly adherent scale, greasy or velvety on the trunk or scalp but harsh, rough, and dry on the face or hands.


Thorough curettage is effective. This leaves a flat surface that becomes covered with normal skin within about 1 week. Pedunculated lesions can be removed surgically. Cautery may produce scarring and should not be used.

Synonym: wart, seborrheic See: illustration

keratosis senilis

An inaccurate synonym for actinic keratosis, which is caused by accumulated ultraviolet light exposure, not by aging.

smokeless tobacco keratosis

Tobacco pouch keratosis.

snuff keratosis

Tobacco pouch keratosis.

solar keratosis

Actinic keratosis.
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STUCCO KERATOSIS: White warty lesions of the dorsum of the fist

stucco keratosis

Benign papules, typically found on the lower extremities, histologically related to seborrheic keratoses. See: illustration

tobacco pouch keratosis

A white, corrugated lesion found on the oral mucosa usually in the muccobuccal fold where chewing tobacco has been habitually placed.
Synonym: smokeless tobacco keratosis; snuff keratosis


Small white patches in the skin arising from excessive local reproduction of the horny outer cells, so that more than the normal amount of KERATIN is formed. Solar keratosis, caused in the elderly by over-exposure to the sun, is a precancerous condition. Keratosis may also affect the hair follicles causing baldness, the outer and middle ears causing obstruction of the ear canal and CHOLESTEATOMA, and the mucous membranes of the lip and of the throat.


A skin disease characterized by an overgrowth of skin, which usually appears discolored.
Mentioned in: Hyperpigmentation


any epidermal lesion characterized by discrete stratum corneum overgrowth

keratosis (keˈ·r·tōˑ·sis),

n skin condition indicated by the presence of noticeable increased growth and thickening of cornified epithelium. Actinic keratosis, seborrheic keratosis, and keratosis senilis are examples of this skin condition.


, pl. keratoses (ker'ă-tō'sis, -sēz)
Any epidermal lesion marked by circumscribed overgrowths of horny layer.
[kerato- + G. -osis, condition]

keratosis (ker´ətō´sis),

n 1. a horny or cornified growth (e.g., wart, callosity).
n 2. a condition characterized by cornification, or hyperkeratinization, of the tissues.
keratosis, actinic,
n an overgrowth of the horny layer of the epidermis caused by excessive exposure to the sun.
keratosis blennorrhagia
n a skin condition found in Reiter's syndrome characterized by pustules and crusting; once incorrectly associated with gonorrhea; more recently considered a genetic disorder occurring mostly in men between the ages of 20 and 25.
keratosis, chronic senile,
n keratosis of the lips in elderly individuals. These lesions should be considered precancerous.
keratosis, focal,
n localized areas of increased cornification (hyperkeratinization). Such lesions are seen particularly on the lips.
keratosis follicularis,
keratosis, seborrheic (basal cell papilloma, verruca senilis)
(seb´ərē´ik pap´əlōmə vəroo´kə sē´nilis),
n benign, pigmented, superficial epithelial tumors that clinically appear to be pasted on the skin of the trunk, arms, or face. Characterized histologically by marked hyperkeratosis, with keratin cyst formation, acanthosis of basal cells, and melanin pigmentation, all above the level of the adjacent epidermis.
keratosis, senile,
n small, firm lesions occurring principally on the face and back of the hands in elderly people or those exposed to the sun. There is hyperkeratosis with irregular and atypical proliferation of the cells of the rete Malpighi. The condition is one of premalignancy with tendency toward epidermoid carcinoma. See also leukoplakia.


any horny growth on the skin, such as a wart or callosity; a firm, elevated, circumscribed area of excessive keratin production. Common in humans but uncommon in animals.

actinic keratosis
varies from a sharply outlined verrucous or keratotic growth to poorly defined areas of erythema, which are premalignant lesions. Due to excessive exposure to the sun. Called also solar keratosis.
equine cannon keratosis
linear keratosis
see equine linear keratosis.
keratosis pilaris
hyperkeratosis limited to the hair follicles.
seborrheic keratosis, keratosis seborrheica
single or multiple elevated plaques and nodules often hyperpigmented with a hyperkeratotic greasy surface. They are benign, of unknown etiology, but have no connection with seborrhea. Occur in dogs and humans.
solar keratosis
see actinic keratosis (above).
References in periodicals archive ?
This Phase II clinical study aims to determine the activity, safety and pharmacokinetics of KX2-391 ointment 1% (5 days or 3 days) in adults with actinic keratosis on the face or scalp.
Sustained Akt activity is required to maintain cell viability in seborrheic keratosis, a benign epithelial tumor.
The superficial epidermal changes of many lesions can overlap; for example, the top of a basal cell carcinoma, an actinic keratosis, and an invasive squamous cell carcinoma, can all appear identical if only the superficial layers of the epidermis are examined.
Five patients were clinically examined and diagnosed to have keratosis obturans provisionally.
We present a case of a generalized non-follicular digitate keratosis that is classified as MMDH according to this algorithm.
After 10 days, I noticed a dramatic improvement to my keratosis pilaris, and three weeks on, I'm still impressed with the results.
In Bangor, 14,200 of the population are over the age of 40, and it is thought, according to the All Wales Medicines Strategy Group (AWMSG), that some 1,562 have actinic or " solar" keratosis.
3 Seborrheic keratosis is a common, benign cutaneous tumour seen in elderly people.
Actinic keratosis are the lesions induced by cumulative effects of UV (Ultraviolet) that may occur in sun-exposed areas of skin1,2 and have the prevalence of 11-25 percent; these lesions are premalignant and have the moderate risk (6-16 percent) of conversion to SCC.
US scientists conducting the new study looked at the effect of celecoxib on 240 people who already had actinic keratosis, pre-cancerous skin damage.
Presuming the diagnosis to be laryngeal keratosis, a premalignant condition, we performed an excisional biopsy using microlaryngeal surgery under general anesthesia.
The most common benign skin lesion is the seborrheic keratosis.