Keratosis

The outermost layer of the epidermis, the horny layer, is made of dead cells rich in keratin, a tough protein that provides the skin barrier. Normally these cells are shed continuously and replaced by others rising from below. When this balance is lost — either through excessive keratin production or through insufficient shedding — localised thickenings appear, generically called keratoses. The term describes an appearance rather than a single disease.

Actinic (solar) keratosis. This develops on areas chronically exposed to the sun: the face, forehead, ears, the scalp in balding people, the upper chest, the forearms and the backs of the hands. It is the consequence of damage accumulated over years by ultraviolet radiation in the cells of the epidermis. The lesions are small, a few millimetres across, pink, reddish or skin-coloured, covered by a rough scale; they are often easier to feel with a finger than to see. They may be tender, may peel and then reappear in the same place. Actinic keratosis is considered a precancerous lesion: a proportion of these lesions may progress over time to squamous cell carcinoma, which is why any lesion that grows, bleeds, ulcerates or becomes hard should be shown to a doctor. The risk is higher in people with fair skin who burn easily, in those who have worked outdoors for many years, and in people with reduced immunity.

Seborrheic keratosis. This is a benign lesion, very common after the age of 40 to 50. It appears as a round or oval, well-defined plaque with a dull, greasy or warty surface, yellowish, brown or almost black, looking as if it were “stuck on” the skin. It occurs most often on the trunk, back, face and neck. The number of lesions increases with age, and the predisposition is often familial. It is not linked to sun exposure in the same way as actinic keratosis and does not turn malignant, but at first glance it can be confused with pigmented lesions that do require assessment, so a new lesion that rapidly changes colour or shape should be examined.

Keratosis pilaris. This is a benign and very widespread condition in which keratin builds up at the opening of the hair follicle and forms small plugs. The skin takes on a “goose bump” appearance, with small rough papules, skin-coloured or slightly reddish, on the outer surface of the arms, on the thighs and buttocks, and sometimes on the cheeks in children. It commonly appears in childhood and adolescence, runs in families, and is more obvious in people with dry skin or atopic dermatitis. It worsens in winter, when cold dry air dehydrates the skin, and often improves in summer. It is not contagious and is not painful, but it can be cosmetically bothersome.

Factors that favour the appearance of keratoses:

• Cumulative sun exposure and the use of tanning devices (for actinic keratosis).
• A fair phototype, with skin that burns easily and does not tan.
• Older age and a family history.
• Constitutionally dry skin and an atopic tendency (for keratosis pilaris).
• Immunosuppression, whatever the cause.

What can make the lesions look worse:

• Unprotected sun exposure, especially in the middle hours of the day.
• Scratching, harsh rubbing and aggressive mechanical exfoliation.
• Very hot baths and strongly degreasing soaps, which dry the skin.
• Dry indoor air during the cold season.
• Repeated irritation from rough or tight clothing.

Because the same name covers both trivial lesions and lesions that need monitoring, any newly appeared keratosis that grows, changes or bleeds deserves examination by a dermatologist.

In our practice, keratoses are addressed through the Kozak Method — internal and external treatment, individually tailored, following a consultation. Results differ from patient to patient.