SQINpedia - The SQIN Skin Glossary


The encyclopedia for all topics related to your skin. No matter if you discover changes or want to inform yourself - our skin glossary helps you to orientate yourself in all relevant topics.

If you suspect you have a skin disease, contact a dermatologist. For an initial check, the SQIN app is the perfect place to start.




Signs are constantly or episodically occurring pimples and inflamed skin areas, which visually resemble a skin rash. Acne develops from an interaction of various genetic factors. A chronic inflammation of the sebaceous gland follicles is triggered.

Type 1: Acne neonatorum

Acne type 1 occurs in newborns, mostly as pimples on the cheeks, forehead or chin area. On average, 20% of babies are affected. Male babies are affected more frequently. 

Type 2: Acne infantum

This form of acne affects infants on the face, usually between the third and twelfth months of life. Boys are significantly more susceptible than girls. Those affected suffer from nodules in the skin or purulent pustules.

Type 3: Acne vulgaris

Acne vulgaris is the best-known form of acne, occurring during puberty in areas such as the face or trunk. More than 70 % of adolescents show acne-typical skin changes, which in some cases last until the age of 25. 

Type 4: Acne tarda

Acne type 4 is also known as late acne and usually occurs on the chin and jaw area of the face. The main causes are hormonal fluctuations, such as those caused by pregnancy, the start or discontinuation of hormonal contraception, or occupational stress.


Monkeypox is a viral disease that occurs symptomatically on the skin. The disease usually heals on its own. The treatment refers to the symptoms. Monkeypox manifests itself in itchy skin lesions, which can be treated dermatologically. Fever as well as muscle and joint pain can be further symptoms.

Age warts (Verrucae seborrhoicae)

Senile warts are harmless skin tumors that usually occur in older people. They are recognizable by protruding, round, shiny skin nodules in light or darker shades of brown. The warts can occur on the entire body except on the mucous membranes and can be surgically removed if the affected person is cosmetically disturbed.


Aphtae are painful but usually harmless inflammations of mucous membranes, such as in the mouth or genital area. They can be recognized by white or yellowish round spots. Usually, aphthae are associated with an overreaction of the immune system, which is often triggered by infectious diseases or nutrient deficiencies.

Drug allergy (drug exanthema)

In drug exanthema, the skin shows an allergic reaction to the ingredients of medications. The allergy can occur through the use of ointments or tablets and manifest itself after a few minutes, but also after hours. Spots, pustules, swelling, itching or shortness of breath are typical symptoms.


Texture skin types

The nature of skin types can change throughout life due to internal or external influences.

Dry skin

Dry skin can be recognized by the fact that without hydration it often feels rough and taut. It produces little sebum, which means it lacks a protective film against moisture loss. 

oily/greasy skin: 

Excessive production of sebum leads to shiny, oily skin that is more prone to pimples.

Combination skin

With combination skin, dry as well as oily areas are found on the skin. Often the skin around the T-zone on the face (forehead, nose, chin) is oily and on cheeks dry.

Normal skin

Normal skin is neither particularly dry nor oily and causes few or no skin problems. Sebum production is in balance.

Impetigo contagiosa (Impetigo contagiosa)

Impetigo contagiosa is a highly contagious bacterial skin infection that occurs mainly in children. It is caused by bacteria. The infection manifests itself in the form of red, itchy blisters or pustules that can burst open to form sores or crusts. It is transmitted through direct skin contact or touching infected objects. Treatment usually involves topical application of antibiotic creams or ointments to fight the infection and promote skin healing.

Lyme disease

Lyme disease is an infectious disease that is mainly transmitted by ticks. Lyme disease should be treated to avoid late effects. These can be, for example, damage to the brain or heart.


Cafe-au-lait stains

Light brown skin spots are also called cafe-au-lait spots. In general, these are harmless skin changes. In individual cases, this pigment change is a concomitant of other diseases and should therefore be examined by a dermatologist.


Cellulite is a common skin condition that is manifested by an uneven and lumpy appearance of the skin. Cellulite is believed to be caused by a combination of genetic factors, hormonal changes and poor circulation. There are several treatments for cellulite that improve the appearance of the skin, such as massages, creams and laser treatments.


Clamydia is a sexually transmitted venereal disease that can lead to infection when pathogens come into contact with mucous membranes. The disease can be recognized by pain during urination, purulent discharge or skin redness or rash in the genital area. In all cases, it should be treated with medication to avoid consequences such as infertility.


Stretch marks(striae distensae)

Stretch marks occur when the connective tissue of the skin is overstretched, resulting in scarring. They can be caused by rapid growth, weight gain or hormonal changes. Most often they appear on parts of the body such as the abdomen, hips, thighs or breasts.


Genital warts (Condylomata acuminata)

Human papillomavirus (HPV) infection is the most common cause of genital warts. They can appear on the genitals, anus or around the mouth. Most cases of genital warts do not cause symptoms. Itching, pain, or bleeding rarely occur. Genital warts can be removed with the help of creams or ointments.

Fire stain (nevus flammeus)

Port-wine stains are congenital skin lesions caused by abnormal growth of blood vessels. They appear as reddish-purple patches on the skin and can occur in a variety of locations and sizes. Treatment options include laser therapies, surgical removals, and drug treatments.


Boils are inflammations that reach into the deepest layers of the skin. At the beginning, they are usually small in area, but as the disease progresses, they swell into painful, purulent nodules. If they do not empty on their own within a few days, they should be treated immediately by a doctor. Boils often leave small scars.

Athlete's foot (Tinea pedis)

Athlete's foot is often caused by a moist area between the feet and is a contagious skin disease. The skin areas are reddened, flake, form a horny layer or cracks. If the fungus remains untreated, it spreads. Frequently, nail fungus also occurs at the same time.


Granuloma annulare

Granuloma annulare is a benign skin disorder in which round or semicircular skin lesions occur. It often affects the hands, feet, arms or legs and is most common in children and young adults. The exact cause of granuloma annulare is unknown, but an impaired immune response is thought to play a role.


Hair folliculitis (folliculitis)

Folliculitis is an inflammation of the hair follicles caused by bacteria, viruses, fungi or an immune deficiency. The inflammation manifests itself as pimples, nodules and red swellings mostly on the head, beard or chest hair. Increased hygiene and cooling of the affected skin area can accelerate healing in mild cases. In the case of severe symptoms, consultation with a doctor should be sought.


When the blood vessels in the anal area are enlarged, symptoms such as pain during defecation, bleeding, itching or oozing occur. The natural function of hemorrhoids is to seal the sphincter muscle. In case of physical or mental overload or lack of exercise, excessive swelling occurs. 

Hand-foot-and-mouth disease

Hand-foot-and-mouth disease is a highly contagious viral disease that occurs mainly in preschool children. Typical symptoms include fever, sore throat, loss of appetite, and the appearance of vesicles or small ulcers on the palms of the hands, soles of the feet, and around the mouth. The disease is transmitted through direct contact with infected secretions, such as saliva or stool. Treatment focuses on symptom relief, such as antipyretics and analgesics, and good hygiene. In most cases, the disease heals on its own.

Skin cancer

White skin cancer / basal cell carcinoma

White skin cancer, also known as basal cell carcinoma, is recognizable by a red, shiny spot with a conspicuous border. It is mainly caused by UV rays and usually occurs in the head and neck area. Fair skin types are more susceptible to white skin cancer.

White skin cancer / spinocellular carcinoma

Spinocellular carcinoma is a form of white skin cancer. Symptoms are horny or scaly areas on the skin or nodules. Causes and appearance are very similar to basal cell carcinoma.

Black skin cancer / melanoma

Indications for black skin cancer are dark spots on the skin, which can also be bluish, reddish or brownish in color. Often these are mistaken for a peculiar mole or liver spots. They develop due to sun damage. In advanced stages, offshoots from the tumor cells (metastases) spread throughout the body.

Skin sensitivity

Skin sensitivity describes how resistant the top layer of skin is to external influences. Heat, cold, mechanical irritation, UV rays or even fragrances trigger symptoms such as redness, tightness or scaly patches much more quickly in sensitive skin. The causes are many and varied, but can often be traced back to genetic predispositions.



Scabies is a highly contagious parasitic infection of the skin. Itching, fine, dark lines on the skin that develop into vesicles or pustules as the disease progresses are symptoms of the disease. Killing the parasites is possible by basic cleaning of textiles.


Eyelid eczema

Eyelid eczema is an acute or chronic inflammation of one or both eyelids. Symptoms are scaly areas, redness, itching, oozing or crusting in the eyelid area. Common causes are allergies to make up, contact lenses or pollen. The type of treatment must be tailored to the cause.


Lymphedema is a chronic condition caused by a disorder of the lymphatic system. It occurs when lymph fluid cannot drain normally and accumulates in the tissues. It can be congenital or caused by injury, infection or cancer. Typical symptoms include swollen arms or legs, tightness, pain and limited mobility. Treatment includes physical therapies such as compression bandaging, manual lymphatic drainage and exercise therapies to promote lymphatic flow. In some cases, surgery may be required to treat lymphedema.


Merkel cell carcinoma

Merkel cell carcinoma is a rare and aggressive form of skin cancer. It develops from the Merkel cells, which are located in the hair follicles. It mainly occurs in sun-exposed areas such as the face, neck or arms. Typical symptoms include a fast-growing, painless lump or tumor that may appear reddish or purple. Treatment usually involves a combination of surgical removal of the tumor, radiation therapy and/or chemotherapy to stop the progression of the disease. Early treatment is critical to improve prognosis.


Milia, colloquially also called grains of semolina, are harmless, benign cysts of sebum. Those affected may feel cosmetically disturbed by the small white nodules, which often appear around the eye area. Milia can be removed mechanically by a dermatologist or with the help of laser irradiation.


Nail fungus(onychomycosis)

Nail fungus is a contagious fungal infection of the toenails or fingernails. It often develops due to a spread of athlete's foot, immune deficiency or contact with pathogens. In the classic course, the upper edge of the nail is affected first. Later, cavities form in the nail, white streaks or spots and the nail turns yellowish.


Nevus is considered a general term for skin changes such as moles or liver spots. They result from the abnormal growth of pigmented cells in the skin. These can be flat or raised, brown or black, and come in a variety of sizes and shapes. In most cases, nevi are harmless, but should still be monitored to detect changes in appearance or symptoms of skin cancer.


Itchy wheals and a fluid-filled swelling of the uppermost layers of the skin are symptoms of hives. Those affected compare their suffering to contact with stinging nettles. The cause is intolerance, allergies, an immune deficiency or physical stimuli such as heat, cold or friction.

Neurodermatitis / Atopic Dermatitis

People affected by atopic dermatitis complain of itchy spots, rashes, and rough and dry skin that can occur in areas. Responsible for this is a dysfunction of the skin barrier. This makes the skin more susceptible to allergies. Atopic dermatitis is a chronic disease that should be treated together with the dermatologist.



Phlegmon is a bacterial infection that spreads in the surrounding tissue and leads to inflammation. It can occur in various parts of the body, such as the skin, subcutaneous tissue or organs. Typical symptoms include redness, swelling, pain and fever. Treatment usually involves the administration of antibiotics to fight the infection.


Pimples are an inflammatory reaction of the skin. Dead skin cells block the sebaceous glands and hinder the outflow of sebum. The immune reaction of the skin leads to the formation of pus.
Pimples can be caused by internal and external influences. External influences can be reactions to ingredients or active substances or incompatibilities within cosmetic products. Hormonal fluctuations in the body also promote the development of pimples.


Ringworm (Tinea corporis)

Tinea corporis, colloquially known as "ringworm", is a contagious fungal infection that affects the skin of the body. Symptoms are an itchy red or silvery rash, with scaly or dry patches of skin.


Psoriasis (Psoriasis)

Dry, red patches in areas such as the head, elbows or knees can be an indication of psoriasis. This is a chronic inflammatory disease of the skin. An unhealthy lifestyle such as a lot of stress, overweight or smoking is the main trigger and supporter of the disease.

Sunburn(dermatitis solaris)

Sunburn occurs when the skin's own protective mechanisms, such as the formation of melanin, are overloaded. Skin cells are damaged, which becomes noticeable through reddened, pressure-sensitive skin areas with increased temperature. If the damage is severe, blisters appear and the skin peels.

Sweet Syndrome

Sweet syndrome is rare condition characterized by sudden painful skin lesions and inflammation. The exact cause of Sweet syndrome is unknown, but it is thought to be related to an overactive immune response. Typical symptoms include red, painful bumps or nodules on the skin accompanied by fever and general malaise. Treatment includes administration of anti-inflammatory medications and treatment of the underlying cause, if known.



Urticaria is an allergic reaction that can cause itchy skin rashes. The rashes are often red and raised and can spread quickly over the body. The condition can be caused by various triggers such as food, medications, or insect bites.

UV skin types

These skin types are also called the Fitzpatrick skin types. The skin's self-protection time varies from about 15 to 90 minutes depending on the skin type. The self-protection time is the time during which the skin can be exposed to the sun without protection and without redness occurring. Caution: Sun damage due to lack of sun protection affects every skin type and can lead to skin cancer in the long term.

Skin type 1

Skin type 1 is very sensitive to sunlight, gets sunburned quickly and does not tan. People have very light skin and eyes, blond or red hair, very often freckles.

Skin type 2

Fair skin that tans only moderately and tends to sunburn quickly are characteristics of skin type 2. The hair and eye color of those affected tends to range from light colors to brown tones.

Skin type 3

Skin type 3 tans easily and gets sunburn less quickly. It very rarely shows freckles. The color of eyes and hair varies and is often darker.

Skin type 4

An olive skin, dark hair and dark eyes characterize skin type 4. This tans quickly and is little susceptible to sunburn.

Skin type 5

Skin type 5 has brown skin, dark hair and eyes and rarely gets sunburned.

Skin type 6

Skin type 6 has very dark skin, hair and eyes. Due to genetic predispositions, the skin has already reached the full tanning degree and only gets sunburn in very rare exceptional cases.


Chickenpox (varicella)

Chickenpox is a typical viral disease of childhood through airborne or smear infection. Symptoms are initially severe itching leading to reddish papules and later to vesicles filled with clear fluid. In addition, fever occurs.


Vitiligo is a pigment disorder that causes loss of skin color in the form of spots. Particularly noticeable are the white spots on dark skin. Hair, eyes and the inside of the mouth can also be affected and accordingly more sensitive to light.


Warts(Verruca vulgaris)

Warts are round, proliferating spots on the skin. There are various therapies for the treatment of warts, which are recommended especially if they are found to be bothersome. There are different forms of warts- the most common is human pappiloma virus. Genital warts are a special form of warts and should be treated by a dermatologist.

White skin cancer (basal cell carcinoma)

Basal cell carcinoma is one of the most common forms of white skin cancer. See also: White skin cancer / basal cell carcinoma

Diaper rash

Diaper dermatitis mostly affects infants or people with bladder weakness. If the diaper area is constantly moist, the skin swells and is susceptible to infection or fungus. The skin itches, burns, forms small pimples and is reddened.

Erysipelas (erysipelas)

Erysipelas is a bacterial wound infection that leads to severely reddened and swollen skin. In severe cases, pustules and vesicles also form. The tissue under the skin is also affected by the infection, so that the disease can be very painful. Antibiotic treatment is mandatory.



Xanthelasma are harmless, yellowish, flat, greasy deposits that often appear on the eyelids. These have a diameter of 1 to 5 millimeters and are soft in consistency, but can also become thick and hard. Under psychological stress, xanthelasma usually form more frequently and more severely.

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