(ker″ă-tō′sĭs)

(-tō′sēz″)
pl. 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 (″ă-tot′ik), adj.
SYN: keratoma

actinic keratosis

ABBR: 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.

ACTINIC KERATOSIS Actinic skin damage on forehead and scalp

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

SYN: solar keratosis
SEE: sunscreen

keratosis follicularis

SEE: Darier's disease.

keratosis nigricans

SEE: 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.
SYN: lichen pilaris; lichen spinulosus

SYMPTOMS
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.

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


KERATOSIS

keratosis punctata

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

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.

SYMPTOMS
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.

TREATMENT
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.

SYN: wart, seborrheic

SEBORRHEIC KERATOSES ON BACK

SEBORRHEIC KERATOSIS Seborrheic keratoses. (From Goldsmith, LA, Lazarus, GS, AND Tharp, MD:). Adult and pediatric dermatology: A color guide to diagnosis and treatment. Philadelphia: F.A. Davis, 1997. Reprinted with permission.)

keratosis senilis

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

smokeless tobacco keratosis

SEE: Tobacco pouch keratosis.

snuff keratosis

SEE: Tobacco pouch keratosis.

solar keratosis

SEE: Actinic keratosis.

stucco keratosis

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

STUCCO KERATOSIS White warty lesions of the dorsum of the fist

tobacco pouch keratosis

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