What is erythema annulare?

Dermatologists call pathological redness of the skin in a limited area erythema (from the Greek erythros - red), and annular erythema or annular (from the Latin annulus - ring) is not a disease, but a type of skin rash with severe focal hyperemia in the form of a ring. [1]

Epidemiology

As a rule, statistics on the manifestation of symptoms are not kept, so how often erythema annulare appears is unknown.

However, it is known that in Lyme disease (after a tick bite), this type of erythema occurs in 70-80% of patients.

And in almost 70% of cases, erythema annulare is a symptom of skin diseases, mainly fungal.

Approximately 10–20% of children with acute rheumatic fever have marginal anular erythema. [2]

Causes What is erythema annulare?

Like other  types of red spots on the skin of the body , ring-shaped red spots are symptoms of a number of conditions. Therefore, the concept of erythema annulare syndrome combines both morphological variants of this type of rash and their accompanying manifestations, including itching, peeling, hyperkeratosis, etc.

Often, specific causes of erythema annulare (or a specific trigger) cannot be identified, but this does not mean that they do not exist. Such skin manifestations are often caused by infections.

If ring-shaped erythema with a bite of a mosquito, as well as some other insects, can appear only with increased sensitivity of a person, then ring-shaped erythema after a bite of an ixodid tick that transmits the Borrelia burgdorferi spirochete by transmission is a pathognomonic skin symptom  of Lyme disease (lyme borreliosis) .

Erythema migrans annulare with borreliosis occurs a few days after the bite, has a rounded shape and expands rapidly; the center of the hyperemic spot gradually brightens, and there may be a dot or papule at the site of the bite. At an early stage, the symptoms of borreliosis are manifested by fever, general weakness, muscle and joint pain. There is also annular erythema and lymphadenopathy - an increase in regional lymph nodes.

Erythema annulare appears on the face, body, legs and arms - in the form of smooth or scaly plaques with a light spot in the middle - with lupus vulgaris (Lupus vulgaris), that is, skin tuberculosis, caused by Mycobacterium tuberculosis.

With  secondary syphilis  (the causative agent of which is Treponema pallidum spirochete), on the trunk, on the soles and palms of some patients, the appearance of Biett's anular centrifugal erythema is noted - with hyperkeratosis along the edge of rounded spots.

Among viral infections, as causative factors in the appearance of red annular rashes, experts distinguish the herpes virus type III (Varicella  zoster  virus), leading to the development of herpes zoster, which is called  herpes zoster .

Associated with the herpes virus type IV (Epstein-Barr virus),  infectious mononucleosis  is manifested by such symptoms as swelling of the cervical lymph nodes, severe hyperemia of the pharynx, tonsillitis and annular erythema on the skin of the upper body, etc.

Skin reactions often occur in parasitic diseases. So, due to infection with flagellated parasites - trypanosomes (Trypanosoma cruzi), which are carried by triatomine bugs biting people - annular erythema occurs in Chagas disease -  American trypanosomiasis .

And, of course, chronic erythema annulare can be associated with fungal diseases - dermatophytosis or ringworm (for example, when the fungus Trichophyton concentricum, Tinea pedis, Malassezia furfur) is affected. By the way, in adults, this is the most common cause of annular skin lesions.

But the etiology may not be associated with infection. For example, erythema annulare in SLE (systemic lupus erythematosus) most often occurs in cases of subacute cutaneous form of this autoimmune disease - with the main localization on the trunk, in the thighs and buttocks. Details in the publication -  Skin changes in lupus erythematosus .

Ring-shaped erythema in rheumatoid arthritis - an autoimmune disease of the connective tissue of an inflammatory nature - is not observed in everyone. In this case, the affected areas include the skin of the trunk and extremities (on the inside), there is no itching.

In addition, annular erythema can be iatrogenic, provoked by certain drugs and vaccines. [3]

Risk factors

In addition to the diseases listed above, risk factors for the appearance of erythema annulare include:

• sarcoidosis ;
• hepatitis C, liver pathology with cholestasis, biliary cirrhosis;
• diffuse toxic goiter leading to hyperthyroidism;
• Sjögren's syndrome ;
• endocrine pathologies (primarily diabetes mellitus);
• oncological diseases (most often - lymphomas, leukemia, myeloma, tumors of the mammary, prostate or thymus glands);
• increased sensitivity of the body and / or a tendency to allergic reactions;
• genetically determined predisposition;
• pregnancy.

Pathogenesis

Researchers consider the pathogenesis of this form of erythema as the development of a hypersensitivity reaction - skin-vascular (with increased blood flow in the surface capillaries of the skin), associated with an immune response to an antigen: in fungal and parasitic diseases, microbial and viral infections. [4]

An important role in the mechanism of occurrence of annular erythema is played by an increase in the level of eosinophils in the blood -  eosinophilia .

Sometimes anular erythema is part of the paraneoplastic syndrome in oncology, and the main version of its pathogenesis is the effect of cytokines, tumor-associated macrophages and pro-angiogenic factors (in particular, vascular endothelial growth factor VEGF-A).

In diabetic patients, simple annular erythema most likely occurs due to the accumulation of end-products of glycation proteins in the tissues, which activate inflammatory reactions.

Idiopathic familial annular erythema in infants is transmitted with genes - an autosomal dominant type of inheritance.

And in pregnant women, anular erythema is explained by the same hormonal changes: an increase in the level of estrogen and progesterone in the blood.

On the histological side, with annular erythema, certain changes are observed in various layers of the skin: focal exudative inflammation and atrophy of epidermal cells (with a violation of the keratinization process), proliferation of Langerhans cells of the spinous layer, degeneration of cells of the basal layer, edema of the papillary layer. And in the tissues surrounding the skin capillaries - diffuse infiltrates of T-lymphocytes and eosinophils. [5]

Forms

Anular erythema is of several types.

• Annular rheumatic erythema

It is distinguished separately according to the etiological principle.

• Annular erythema migrans

It is considered chronic, compared with manifestations of dermatological diseases of various origins, and in many cases is associated with infections and oncology. In particular, such erythema occurs with Lyme borreliosis.

• Annular centrifugal erythema

Synonyms: erythema annulare Darier, annular marginal erythema. The first signs appear in the form of a small pink papule, which gradually increases to a hyperemic spot (or thin plaque) of a round or oval shape. The increase occurs centrifugally - from the middle to the edges, which on the inside can be covered with scales of exfoliated skin. At the same time, the redness in the center gradually decreases and disappears.

• Annular erythema multiforme

These are non-itchy, sharply defined hyperemic spots that gradually increase with the formation of plaques. In this case, the central part of the erythema is cleared or changes its structure and color.

In addition, some experts distinguish: necrolytic migratory annular erythema (with the formation of blisters, which, after their resolution, become covered with a scab) and persistent paraneoplastic - in oncological diseases.

Erythema annulare in children

In infancy, annular erythema is rare, and, as practice shows, idiopathic annular erythema is most common at this age. [6]

Parvovirus B19 (family Parvoviridae, genus Erythroparvovirus), which affects children, causes not only the usual erythema on the cheeks; within one to two weeks, the so-called annular erythema of Chamer may appear on the trunk and extremities, in which the central part of the elements of the rash gradually begins to turn pale. After a few weeks, it spontaneously disappears, but during the first year of a child's life, it can recur - without any consequences. [7]

As a complication after streptococcal angina or inflammation of the pharynx in children and adolescents, annular erythema may appear with rheumatic fever - one of its main signs associated with activation of inflammation of the joints or heart muscle. For more details, see -  Rheumatic fever .

In this case, ring-shaped erythematous plaques with a clear middle, which do not cause any sensations, quickly increase and quickly disappear, but repeated outbreaks are possible.

You should also keep in mind such no less serious diagnostic options as neonatal lupus erythematosus,  herpes zoster in children , as well as  juvenile rheumatoid arthritis . [8]

Complications and consequences

In some cases, annular erythema disappears spontaneously (sometimes with periodic relapses), in others, if the infection is severe or the disease is systemic, consequences and / or complications arise.

So, with late-stage lyme borrelease, erythema leads to chronic atrophic acrodermatitis affecting the outer surfaces of the upper and lower extremities.

If erythema causes severe itching, then scratching the skin can be subject to secondary infection - with the development of inflammation. [9]

Diagnostics What is erythema annulare?

Although up to now at least half of the cases of ring-shaped red skin rashes are considered idiopathic, diagnosis begins with a visual examination, a study of the patient's medical history (indicating all medications they take and recent vaccinations) and  a skin examination .

For laboratory tests, blood tests are taken: general clinical and detailed, for rheumatoid factor, ELISA for antibodies (to viruses, tuberculosis mycobacteria, streptococcus), for the  C3 complement component in the blood , for eosinophils, for thyroid-stimulating hormones. A general analysis of urine and feces is also given. Allergy testing may be required.

Skin scrapings are done to rule out a fungal infection, and a skin biopsy and histological examination may be required to confirm the diagnosis.   

Instrumental diagnosis may be limited to  dermatoscopy .

Differential diagnosis

Erythema annulare is a non-specific symptom, therefore, the tasks that differential diagnosis should solve are to verify the causative factors and delimit other morphological types of rashes, for example, in granulomatous and atopic dermatitis and dermatomycosis, vulgar (plaque) psoriasis, mastocytosis, erysipelas, etc.. [10]

Treatment What is erythema annulare?

When the disease that caused the appearance of erythema annulare is established, then the main treatment is directed to it.

If this symptom is associated with the third type of herpes virus,  treatment of herpes zoster is necessary .

For severe rheumatoid arthritis in patients older than 18 years, etanercept (Enbrel) may be given subcutaneously. This remedy is prescribed with caution and only in the absence of acute and chronic infections. In the list of its side effects, the following are noted: the development of infectious inflammations of various localization and skin manifestations; negative impact on the nervous, cardiovascular and urinary system and gastrointestinal tract.

Read also -  Treatment of rheumatoid arthritis

With dermatomycosis, topical agents will help to cope -  effective ointments from the fungus .

There are medications to relieve itching: oral  antihistamines  or topical agents in the form  of an itch ointment .

Topical therapy traditionally uses various formulations of  ointments for skin rashes , and in many cases these are ointments and creams with corticosteroids. However, non-hormonal agents are also recommended: Protopic ointment (with tacrolimus) or  Elidel cream  (with pimecrolimus).

In the absence of fungal diseases, systemic corticosteroids can be prescribed: Methylprednisolone,  Betaspan  (Betamethasone, Diprospan), etc., the expediency and scheme of which, with the exact dosage, is determined solely by the attending physician.

Can antibiotics be used for erythema annulare? Treatment with antibacterial drugs against streptococcal infection is carried out with rheumatic fever, for details see -  Treatment of streptococcal infection .

Antibiotics are also used  after a tick bite . And in cases of annular erythema in American trypanosomiasis, the disease itself is treated with antimicrobial agents based on nitrofuran derivatives, which include Nifurtimox. The drug is contraindicated for problems with the kidneys and liver, and the side effects it causes can be manifested by nausea and vomiting, dizziness and headache. [11]

Prevention

There are no measures to prevent the occurrence of this symptom.

Forecast

Even when the cause of annular erythema is unknown, it may disappear spontaneously.

In other cases, this symptom is present for a long time - from three months to a year or more, but by itself it does not affect the prognosis of the outcome of the disease. However, possible recurrences of skin manifestations of chronic diseases have a negative impact on general well-being and reduce the quality of life.