What is keratosis pilaris?

Keratosis pilaris usually occurs between the ages of 8 and 16. The patient's limbs, including the hair follicles, may be broken in many places. In more serious cases, there may be some secretions. The condition will worsen with age, and some papules will appear on the skin. The skin will become thick, heavy and hard.

The disease usually occurs between the ages of 8 and 16, and is rare before the age of 5. There is no obvious racial or gender difference, and the condition may gradually worsen with age. The characteristic skin lesions are hard follicular papules ranging in size from a needle tip to a pea, covered with greasy crusts or bran-like scales. If the scabs are removed, a small funnel-shaped depression can be seen in the center of the papule. The papules are skin-colored at first, gradually increasing in size and merging into irregular wart-like plaques that are brown, dirty black, or dark brown in color. It often occurs symmetrically on the face, chest, abdomen, limbs, and sacrum. The lesions of the trunk are mostly located in the midline and abdomen (Figure 1), the lesions of the face are mostly located in the temporal, frontal, auricular and nasolabial folds, and the limbs are mostly located in the flexion surface. The lesions located on the flexor sides of the limbs, armpits, inner thighs and other areas of sweating and friction are particularly proliferative, often appearing papilloma-like, with purulent secretions and a foul odor.

Skin lesions often occur in areas of sebum secretion, such as the scalp, forehead, ears, sides of the nose, neck, chest, between the shoulder blades, axillae, abdomen, groin, gluteal folds, vulva, and flexor sides of the limbs. The distribution is often extensive and symmetrical, but in about 10% of cases, the lesions are distributed in bands or lines and are limited to one side of the body. Scalp lesions are often covered with greasy crusts and generally without hair loss.

Punctate or diffuse hyperkeratosis of the palms and soles can be seen in about 10% of cases. Individual papules on the back of the hands and feet are similar to verrucous acrokeratosis, and white spots may remain after they disappear.

The nails may be affected, showing symptoms of subungual keratin hyperplasia, thinning and brittleness of the nail plate, and longitudinal white ridges or free edge defects. Sometimes the nail bed changes color.

The disease rarely invades the mucosa, and occasionally white, smooth, flat or umbilical papules, white wart-like patches or leukoplakia-like lesions may be seen on the lips, palate, tongue, buccal mucosa, vagina, esophagus, and cecum. Lung damage is occasionally seen, mainly in the lower lobes; X-ray examination may reveal nodular shadows and diffuse pulmonary fibrosis.

Bone cysts, salivary gland stones, mental retardation, and sexual dysfunction are rare.

Generally there are no subjective symptoms or only mild itching, which may occasionally be severe. The damage may be localized and persist for several years or may progressively spread throughout the body. Ultraviolet rays can aggravate skin lesions, therefore the disease is more severe in summer and milder in winter. General health is rarely affected, and very few skin lesions may develop into squamous cell carcinoma.