Explanation of the causes and symptoms of "keratosis"

• lichen planus

  This is a skin condition characterized by itchy inflammation. It presents as polygonal or map-like raised areas of purple to red skin. It may also be accompanied by sores or scabs. It most commonly occurs on the forearms, wrists, and ankles, but can also appear on the lips, inside the mouth, and around the genitals. Other symptoms may include deformed or detached nails.

• plaque psoriasis

  Psoriasis is one of the most common inflammatory keratosis disorders. It presents as silvery-white, powdery patches on the skin, ranging from 1 to several centimeters in diameter and often reddish in color. In psoriasis vulgaris, the characteristic symptoms of psoriasis appear all over the body, including bumpy rashes. While some people may not experience any symptoms, itching can be present.
  It is commonly seen in areas prone to irritation, such as the head, elbows, knees, and buttocks. In obese individuals, symptoms are more likely to appear in areas where the skin rubs together and experiences friction, such as the elbows and knees. Nail deformation and indentation are also frequently observed.

• Palmoplantar keratoderma

  This is a skin condition characterized by thickening of the keratinized skin on the palms of the hands and soles of the feet. It can be congenital or acquired. The distinction between congenital and acquired is made by considering skin symptoms, symptoms in other organs, family history, and gene mutations, but generally, if it develops by childhood, it is considered congenital, and if it develops in adulthood, it is considered acquired.
  In some cases, only a portion of the skin thickens, while in others, the entire skin thickens uniformly. Other symptoms may include erythema, odor of the hands and feet, and fungal growth.

• sweat hole keratosis

  This is a disease caused by abnormal keratinization of the skin. It manifests as raised keratinized areas bordering the affected area on the limbs, trunk, and face. These raised areas gradually enlarge, but often do not cause itching or pain, resulting in many cases being asymptomatic. It progresses chronically, and spontaneous healing is rare. It is considered a difficult disease to cure completely, and because skin cancer can develop, treatment by a specialist is necessary.

• lichen pilaris

  This condition is characterized by the appearance of small, rough bumps on the upper arms, outer thighs, and buttocks. The bumps are usually skin-colored, but may sometimes appear red. It is most common in children and adolescents, and due to its age and characteristics, it is often mistaken for acne. It is usually painless and itchy, and often disappears with age.

Causes and mechanisms of keratosis

• lichen planus

  It is believed that a reaction occurs that damages cells in the epidermis and dermis, resulting in erythema and papules. The cause of inflammation is unknown, but it is said to be caused by medications such as antihypertensive drugs and cerebral circulation improving drugs, hepatitis C, chemicals such as color film developing solutions, and metal allergies such as dental metals.

• plaque psoriasis

  Three factors are thought to contribute to the development of psoriasis: genetic factors, external factors, and immunological factors.

  ■ Genetic factors

  Psoriasis has a high rate of familial occurrence, suggesting that genetic factors are involved in its development.

  ■ External factors

  Physical irritation (such as trauma or photodermatitis), infection (such as streptococcal infections), and medications (such as lithium preparations, beta-blockers, and calcium channel blockers) are thought to be the causes.

  ■ Immunological factors

  It is believed that abnormalities in the immune system cause signaling molecules such as cytokines to trigger inflammation, preventing normal keratinization (division of epidermal cells).

• Palmoplantar keratoderma

  Congenital forms of the disease are known to be associated with various genetic abnormalities. While the specific genetic abnormalities causing some cases are known, others remain unknown. Furthermore, the disease can suddenly develop in individuals with no family history (no close relatives having had the disease).
  Acquired forms of keratosis can be caused by malignant diseases. The onset of keratosis can sometimes lead to the discovery of cancer hidden in internal organs. Other causes include menopausal keratosis in middle-aged and older women, as well as medications and infections.

• sweat hole keratosis

  It is a genetic disorder, but the specific gene abnormality causing it is not yet clear. Many cases occur without a family history. Other known contributing factors include ultraviolet radiation, trauma, and immunosuppression. Although the name of the disease includes "sweating pores," the affected area is not limited to sweat pores.

• lichen pilaris

  It is thought to be caused by an abnormality in skin cell turnover. When keratin accumulates excessively in the pores, the keratin around the pores thickens and blocks the pores, causing the tips of the comedones to protrude and appear as bumps on the skin surface. There is also a theory that it is genetic, but it has not yet been clearly explained.