In the field of dermatology, an erythema is a term which designates redness skin. For example, the following can cause erythema(s): a bite, measles, sunburn, an allergywhen we blush because we are embarrassed… In most cases, an erythema is benign, but sometimes it is the manifestation of a more severe disease. How to recognize an erythema? What can cause it? How to treat it?

What is the definition of erythema?

“In dermatology, erythema is the first of the basic lesions of the skin (basic lesions include macules, papules, etc.). Erythema corresponds to a more or less intense redness due to the dilation of the superficial vessels of the skin. in the dermal papillae. It is almost the easiest lesion to diagnose. This redness can be visible in a multitude of contexts“, explains Dr. Isabelle Rousseaux, dermatologist.

“Erythema is characteristic of erase by vitropression, in other words, when you press it“, emphasizes our interlocutor. Erythema is therefore a redness which can be localized on a particular area (skin folds, burns), regional or generalized to the whole body. Depending on the cause, erythema can to accompany :

• Small, pale pink maculeswell separated from each other (in rubella for example, we speak of erythema roseoliform)
• Patchy red macules and papules separated by spaces of healthy skin (rash of measles, it is called erythema morbiliforme)
• Diffuse bright red patches without a gap of healthy skin that may peel (in scarlet fever for example, we speak of scarlatiniform erythema)
• Itching (in drug poisoning for example)
• Fever and fatigue (in an infectious context).

Photos of an erythema

Causes: what causes erythema?

“Erythema is a sign that corresponds to hundreds of causes“, warns Dr. Rousseaux.

► “Symptom” erythema is found in all inflammatory skin conditions and is part of the clinical picture of many dermatological conditions:

• Psoriasis
• Rosacea (erythrosis of the face that affects the cheeks, nose, and chin, the flare-ups of which are favored by emotional food factors and the thermal environment)
• eczema
• drug eruption
• Lupus
• Diaper rash which is an infant skin irritation…

► Erythema can also be due, for example, to:

• A burn or sunburn (localized erythema)
• An insect bite (erythema centered by a sting point)
• A Sun exposure (also called solar erythema)
• Natural redness between skin folds (under the armpit, under the breast, when you cross your legs, etc.)
• Measles or scarlet fever
• rubella
• A syphilis
• An epidemic erythema, called “fifth disease”
• A toxic reaction or a reaction to a drug (allergy)
• An infection: intertrigo, erysipelas, erysipeloid, pasteurellosis, trichinosis

What is erythema nodosum?

Erythema nodosum is an acute inflammation of the hypodermis, in other words the deep layer of the skin. It mainly reaches young adultsmost often on the lower limbs, on the inside of the leg. It may also due to an infection (streptococcus, tuberculosis, infectious mononucleosis, etc.) or a general illness (sarcoidosis, aphthosis), inflammatory colitis (Crohn’s disease, ulcerative colitis) or taking medication (aspirin, contraceptive pill). It evolves in flare-ups and leaves no scar.

What is erythema multiforme?

Erythema multiforme is a skin condition characterized by lesions in the shape of a cockade, which indicates a state of hypersensitivity. Among the causes, we mainly find viral infections (herpes, shingles, chickenpox, flu, infectious mononucleosis, hepatitis B, etc.), microbial (tuberculosis, leprosy) or taking certain drugs (penicillin, sulfonamides, etc.). Rather, it touches young men and is most often manifested by the appearance of red patches of a typical appearance: a central bubble surrounded by a first crown of white skin, then by a second crown with several bubbles.

What is erythema migrans?

Erythema migrans is the most constant and characteristic sign of Lyme disease, a borreliosis transmitted by a tick bite. It’s about a round or oval shaped rash.

→ If there is an obvious cause of erythema such as sunburn or insect bite for example: the application of a cream linked to the cause is sufficient and the erythema usually disappears spontaneously.

→ In case of fever, generalized erythema or suspicion of poisoning, it is best to quickly consult your general practitioner to find the cause and set up a treatment. A consultation with a dermatologist can also be considered if necessary.

→ If it is erythema nodosum: its treatment is that of the cause if it is identified. Otherwise, it is only aimed at treating the symptoms with rest and taking anti-inflammatory medications.

→ In case of isolated erythema migrans without other clinical signsantibiotic therapy is essential and must be started quickly.

Thanks to Dr Isabelle Rousseaux, dermatologist and venerologist in Lille.

Source : Elementary dermatological lesions, French Society of Dermatology