What is erythema annulare?

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

Epidemiology

Typically, statistics on the occurrence 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, mostly 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 patches on the body, ring-shaped red patches are symptoms of a number of conditions. Therefore, the concept of erythema annulare syndrome combines both morphologic variants of this type of rash and its associated manifestations, including itching, desquamation, hyperkeratosis, and others.

Often the specific cause of erythema annulare (or specific trigger) cannot be identified, but this does not mean that there is no cause. Such skin manifestations are often caused by infections.

While ring-shaped erythema in the bite of a mosquito, as well as some other insects may appear only in case of hypersensitivity of a person, ring-shaped erythema after the bite of a tick of the ixodid family, transmissively transmitting the spirochete Borrelia burgdorferi, is a pathognomonic skin symptom Lyme disease (lyme borreliosis),

Migrating annular erythema in borreliosis occurs a few days after the bite, is rounded and rapidly enlarges; the center of the hyperemic spot gradually lightens, and there may be a dot or papule at the site of the bite. In the early stage, symptoms of borreliosis are manifested by fever, general weakness, muscle and joint pain. There is also annular erythema and lymphadenopathy - enlargement of regional lymph nodes.

A ring-shaped erythema on the face, body, legs and arms - in the form of smooth or scaly plaques with a light spot in the middle - appears in Mycobacterium tuberculosis vulgaris (Lupus vulgaris), i.e., cutaneous tuberculosis.

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

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

Associated with herpes virus type IV (Epstein-Barr virus) infectious mononucleosis presents with symptoms such as swollen neck lymph nodes, marked hyperemia of the pharynx, tonsillitis and ring-shaped erythema on the skin of the upper body, among others.

Skin reactions often occur in parasitic diseases. For example, due to infection with flagellated parasites - trypanosomes (Trypanosoma cruzi), which are carried by triatom bugs that bite people - ring-shaped erythema occurs in Chagas disease - American trypanosomiasis.

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

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

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

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

Risk factors

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

• sarcoidosis;
• Hepatitis C, liver pathologies with cholestasis, biliary cirrhosis;
• Diffuse toxic goiter leading to hyperthyroidism;
• Sjögren's syndrome;
• endocrine pathologies (primarily diabetes mellitus);
• cancer (most commonly lymphoma, leukemia, myeloma, tumors of the breast, prostate or thymus glands);
• hypersensitivity of the body and/or tendency to allergic reactions;
• genetic predisposition;
• pregnancy.

Pathogenesis

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

An important role in the mechanism of anular 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 proangiogenic factors (in particular, vascular endothelial growth factor VEGF-A).

In patients with diabetes mellitus, simple annular erythema is likely due to the accumulation of protein glycation end products in the tissues, which activate inflammatory reactions.

Idiopathic familial erythema annulare in infants is transmitted with a gene-autosomal dominant type of inheritance.

And in pregnant women, anular erythema is explained by all the same hormonal changes: increased levels of estrogen and progesterone in the blood.

Histologically, in ring-shaped erythema there are certain changes in different layers of the skin: focal exudative inflammation and atrophy of epidermis cells (with impaired keratinization), 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 skin capillaries - diffuse infiltrates of T-lymphocytes and eosinophils. [5]

Forms

Anular erythema comes in several types.

• Rheumatic erythema circularis.

Distinguished separately on the basis of etiologic principle.

• Ring-shaped erythema migrans.

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

• Ring-shaped centrifugal erythema.

Synonyms: annular erythema darier, annular marginal erythema. The first signs appear as a small pink papule that gradually enlarges to a hyperemic spot (or thin plaque) with a circular or oval shape. The enlargement occurs centrifugally - from the middle to the edges, which on the inside may be covered with scales of detached skin. At the same time, the redness in the center gradually decreases and disappears.

• Ring-shaped erythema multiforme.

These are non-pruritic, sharply defined hyperemic spots that gradually enlarge to form plaques. The central part of the erythema is cleared or changes in structure and color.

In addition, some specialists distinguish: necrolytic migratory annular erythema (with the formation of blisters, which after their resolution are covered with scabs) and persistent paraneoplastic - in cancer.

Erythema circularis in children

Anular erythema anularis is rare in infancy, and idiopathic annular erythema has been shown to be most common at this age. [6]

Parvovirus B19 (family Parvoviridae, genus Erythroparvovirus), which affects children, not only causes the usual erythema on the cheeks; within one to two weeks, the so-called Chamer's ring erythema may appear on the trunk and limbs, in which the central part of the rash gradually becomes pale. It resolves spontaneously after a few weeks, but may recur during the first year of life - without any consequences. [7]

As a complication of streptococcal sore throat or sore throat, children and adolescents may have erythema annulare in rheumatic fever, one of its main signs associated with activation of inflammation of the joints or heart muscle. For more information see. - Rheumatic Fever.

In this case, non-sensation-inducing annular erythematous plaques with a clear center enlarge rapidly and disappear quickly, but recurrent flare-ups are possible.

Equally serious diagnostic variants such as neonatal lupus erythematosus, herpes zoster in children, and juvenile rheumatoid arthritis should also be kept in mind. [8]

Complications and consequences

In some cases, anular erythema disappears spontaneously (sometimes with periodic recurrences), in others, if the infection is severe or the disease is systemic, there are consequences and/or complications.

For example, in lyme borreliosis, late-stage erythema leads to chronic atrophic acrodermatitis affecting the outer surfaces of the upper and lower extremities.

If erythema causes severe itching, the skin combing may undergo secondary infection - with the development of inflammation. [9]

Diagnostics What is erythema annulare?

Although at least half of the cases of ring-shaped red skin rashes are still considered idiopathic, diagnosis begins with a visual examination, review of the patients' medical history (including all medications taken and recent immunizations) and skin examination.

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

A skin scraping is done to rule out fungal infection, and a skin biopsy and histologic examination may be required to confirm the diagnosis.

Instrumental diagnosis may be limited to dermatoscopy.

Differential diagnosis

Ring-shaped erythema refers to nonspecific symptoms, so the tasks that should solve the differential diagnosis are to verify the causative factors and to distinguish other morphological types of rashes, for example, in granulomatous and atopic dermatitis and dermatomycosis, psoriasis vulgaris (plaque), mastocytosis, rash inflammation, etc., and other morphological types of rashes. [10]

Treatment What is erythema annulare?

When the disease that caused the ring-shaped erythema is identified, the main treatment is directed at it.

If this symptom is associated with the third type of herpes virus, you need treatment for shingles.

In severe rheumatoid arthritis in patients over 18 years of age, Etanercept (Enbrel), which is administered subcutaneously, may be used. This drug is prescribed with caution and only if there are no acute and chronic infections. In the list of its side effects are noted: the development of infectious inflammation of various localizations and skin manifestations; negative effects on the nervous, cardiovascular and urinary systems and the GI tract.

Read also - Treating Rheumatoid Arthritis

Dermatomycosis can be treated with topical agents - effective ointments for fungus.

There are medications to relieve itching as well: taken orally antihistamines or topical agents in the form of itch ointments.

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

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

Can antibiotics be used for erythema annulare? Treatment with antibacterial drugs against streptococcal infection is given for rheumatic fever, for more information see. - Treatment of streptococcal infection.

Also used antibiotics after a tick bite. And in cases of ring-shaped erythema in American trypanosomiasis, the disease itself is treated with antimicrobials based on nitrofuran derivatives, which include Nifurtimox. The drug is contraindicated in kidney and liver problems, and its side effects may be manifested by nausea and vomiting, dizziness and headache. [11]

Prevention

There are no preventative measures for the onset of this symptom.

Forecast

Even when the cause of anular erythema is not identified, it can disappear spontaneously.

In other cases, this symptom is present for quite 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 negatively affect the general well-being and reduce the quality of life.