Allergodermatoses: forms, symptoms, approaches to therapy

Allergodermatoses in children are a group of inflammatory skin diseases caused by immune responses to external or internal allergens and sensitizing factors. The most common include atopic dermatitis, urticaria, allergic contact dermatitis, drug-induced skin reactions, and some reactions to insect bites. These conditions significantly reduce the quality of life for the child and family, requiring early diagnosis, elimination of triggers, and step-by-step therapy based on age and severity. [1]

The main symptoms include itching, erythema, papulovesicular elements, excoriations, lichenification, and varying degrees of edema. Urticaria is characterized by itchy wheals and angioedema, allergic contact dermatitis by focal eczema at the site of contact with the allergen, and atopic dermatitis by a chronic, relapsing course with age-related localization. In severe cases, systemic manifestations and the risk of anaphylaxis are possible with combined food or drug reactions. [2]

In recent years, the therapeutic arsenal has expanded: phototherapy, targeted biologics, and Janus kinase inhibitors have been added to basic emollients and anti-inflammatory topical agents. This has improved control of moderate to severe forms, including in adolescents, but has increased safety and monitoring requirements. [3]

A comprehensive approach includes family education on skin care, identification and minimization of triggers, stepwise treatment of flare-ups, and regular reassessment of the diagnosis in cases of atypical progression. Early reliance on evidence-based recommendations reduces the risk of chronicity and complications. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, the key headings are: L20 "Atopic dermatitis," L23 "Allergic contact dermatitis," and L50 "Urticaria." Additionally, for drug-induced dermatitis, L27 "Dermatitis due to substances ingested" is used, and for food reactions, codes in the T78 range are possible. Clarifying subheadings allow for coding of individual variants and causes. [5]

In the International Classification of Diseases, Eleventh Revision, atopic dermatitis is classified in block EA80, "Atopic Eczema," with a distinction made between childhood forms; allergic contact dermatitis is classified in block EK00; and urticaria is classified in block EB00, "Spontaneous Urticaria," with a subdivision into acute and chronic forms. When compiling statistics, it is important to use current versions of the codes and, if necessary, add additional features regarding the course and causative factors. [6]

Table 1. The most commonly used codes for recording allergic dermatoses in children

Classification	Code	Name
ICD-10	L20	Atopic dermatitis
ICD-10	L23	Allergic contact dermatitis
ICD-10	L27	Dermatitis caused by substances ingested
ICD-10	L50	Hives
ICD-11	EA80.1	Childhood atopic eczema
ICD-11	EK00	Allergic contact dermatitis
ICD-11	EB00.0 EB00.1	Acute and chronic spontaneous urticaria
Source: official reference codes ICD-10 and ICD-11. [7]

Epidemiology

Atopic dermatitis is the most common allergic dermatosis in children. Current global prevalence estimates indicate that approximately 4% of children worldwide suffer from it, with the rate significantly higher, reaching double-digit levels, in certain countries and age groups. The disease burden has been increasing in recent decades. [8]

Urticaria occurs throughout life in a significant proportion of the population; acute episodes are common in children, while the chronic form is less common. Estimates indicate a prevalence of chronic urticaria in pediatric patients of approximately 1.4%, with acute episodes occurring significantly more frequently at different stages of life. [9]

Allergic contact dermatitis is less commonly diagnosed in children than in adults, partly due to under-reporting, but large registries and case series demonstrate a high proportion of positive patch tests among referred patients and support the importance of this diagnosis even in children under 6 years of age. [10]

The burden on the healthcare system and families is significant: itching, sleep disturbances, missed school and preschool visits, psychological consequences, and the economic costs of care and treatment. Proper stratification of severity and early access to effective therapy reduce the individual and population burden of the disease. [11]

Reasons

The causes of allergic dermatoses are multifactorial and include genetic predisposition, characteristics of the skin barrier and immune response, and exposure to allergens and nonspecific irritants. In atopic dermatitis, epidermal barrier disturbances associated with variants of skin protein genes play a significant role, facilitating the penetration of allergens and the development of inflammation. [12]

Urticaria in children develops as a result of mast cell activation and the release of mediators. It is most often triggered by infections, dietary and medicinal factors, cold, and physical impacts. In chronic cases, autoimmune mechanisms are possible. Histamine and other mediators play a key role, causing wheals, itching, and swelling. [13]

Allergic contact dermatitis is caused by a delayed-type immune response to low-molecular-weight haptens, which, after penetrating the skin, bind to proteins and trigger sensitization. Typical allergens in children include nickel, cobalt, preservatives, fragrances, rubber chemicals, and components of personal care products and toys. [14]

Drug-induced allergic dermatoses arise from immune reactions to systemic or topical medications, as well as dietary supplements. The risk increases with concomitant atopy and polypharmacy. A combination of several mechanisms and overlapping clinical phenotypes are possible in any age group. [15]

Risk factors

Familial and personal atopy, early skin barrier dysfunction, and dry skin increase the likelihood of atopic dermatitis and the subsequent "atopic march," that is, the transition to allergic rhinitis and bronchial asthma. Anthropogenic environmental factors, including urbanization and microbiome changes, are also considered. [16]

Recent viral infections, physical triggers, food and drug exposures, and, in chronic forms, autoimmune processes are significant for urticaria. Girls and young children may have a slightly higher prevalence of certain phenotypes. [17]

Allergic contact dermatitis is associated with frequent and prolonged skin contact with allergens. The risk increases with nickel-based jewelry and accessories, exposure to preservatives in cosmetics and household chemicals, and hobbies and games involving glue and plastics. Underdiagnosis is associated with the infrequent referral of children for patch testing. [18]

Drug-induced skin reactions are more common when taking multiple medications at the same time, during infections, and in children with a predisposition to allergic reactions. A thorough history and documentation of reactions are important to prevent recurrences. [19]

Pathogenesis

In atopic dermatitis, the primary disturbances are the skin barrier and innate immunity, with a predominance of T-cell responses of a specific profile, which maintains chronic inflammation and itching. The damaged barrier facilitates sensitization and the "vicious cycle" of itching and scratching. [20]

Urticaria is caused by the activation of mast cells in the skin and the release of histamine and other mediators, causing vasodilation, increased vascular permeability, and wheal formation. In the chronic spontaneous form, autoimmune activation of mast cell receptors is possible. [21]

Allergic contact dermatitis is a delayed-type reaction in which sensitized T-lymphocytes, upon repeated exposure to the allergen, trigger inflammation and the clinical picture of eczema at the site of exposure. Immune memory maintains a long-term readiness to react even with minimal contact. [22]

Drug-induced skin reactions are mediated by various immune pathways and can mimic other dermatoses. Understanding the mechanism is important for selecting therapy and for making an informed decision about the possibility of desensitization or complete avoidance of the drug. [23]

Symptoms

Atopic dermatitis manifests as dryness, erythema, infiltration, and itching, primarily on the face and extensor surfaces in infants and in skin folds in schoolchildren and adolescents. Lichenification is characteristic in chronic cases and secondary infections are frequent due to scratching. [24]

Urticaria produces migratory, itchy wheals ranging from a few millimeters to centimeters in size with a pale center and an erythematous halo, persisting in one location for less than 24 hours. Angioedema is accompanied by dense, painless swelling of the eyelids, lips, extremities, and sometimes the larynx. [25]

Allergic contact dermatitis is limited to the area of contact, beginning with erythema and edema, followed by papules, vesicles, oozing, and crusting. Chronic contact leads to dryness, cracking, and lichenification. In children, the hands, face, and ears are often affected. [26]

Drug-induced dermatoses vary in the appearance of the rash and may be accompanied by fever and systemic complaints. In any case, a connection with the onset of the drug is concerning, and regression after discontinuation increases the likelihood of a causal connection. [27]

Classification, forms and stages

Atopic dermatitis is classified into age-specific stages with typical lesion locations and severity scales that take into account the area, intensity of lesions, and itching. This helps standardize treatment strategies and evaluate treatment effectiveness over time. [28]

Urticaria is classified as acute and chronic. The chronic form is subdivided into spontaneous and induced, the latter being triggered by cold, pressure, heat, cholinergic, and other factors. Confirmation of the induced forms is based on reproducible provocative tests. [29]

Allergic contact dermatitis is classified by the causative allergens and clinical course as acute or chronic. Children often have sensitization to metals, preservatives, and fragrances, which dictates the choice of patch testing panels. [30]

Skin drug reactions are classified by clinical phenotype and severity, ranging from limited rashes to severe forms. Any suspicious rash associated with the drug requires a risk assessment and a decision on immediate discontinuation. [31]

Table 2. Conventional scale of severity of skin process for therapy planning

Degree	Key Features	Tactics
Light	Small area, moderate itching, rare exacerbations	Basic care, external anti-inflammatory agents as needed
Average	Severe itching, large area, regular flare-ups	Regular anti-inflammatory topical therapy, discussion of phototherapy
Heavy	Extensive lesions, sleep and learning disorders, frequent exacerbations	Escalation to phototherapy and systemic agents, consideration of biological therapy
Source: adapted from clinical guidelines. [32]

Complications and consequences

Persistent itching leads to sleep disturbances, fatigue, decreased concentration and academic performance, as well as anxiety and depressive symptoms in the child and parents. Uncontrolled chronic itching worsens psychosocial adaptation and quality of life. [33]

Damage to the barrier and scratching increase the risk of bacterial and viral skin infections, including impetigo and eczema herpeticum. With urticaria, angioedema in the larynx can be accompanied by severe discomfort and requires emergency care if breathing becomes compromised. [34]

Without eliminating the trigger, allergic contact dermatitis becomes chronic, leading to cracking, pain, limited activity, and the development of persistent sensitization. Long-term use of ineffective medications and self-medication increase the risk of side effects. [35]

The economic burden includes direct costs for medications and emollients, return visits and hospitalizations, and indirect losses due to missed school and work by family members. Effective early treatment reduces overall costs. [36]

When to see a doctor

You should seek medical attention if you experience a new, widespread rash with severe itching, suspected contact with a potential allergen, symptoms of angioedema, or any worsening of your general condition. Fever, skin tenderness, painful cracks, and significant sleep disturbances are all warning signs. [37]

Immediate assistance is needed if signs of respiratory tract involvement, increasing swelling of the face and tongue, difficulty breathing, severe generalized itching with dizziness and weakness occur. These situations are considered a possible systemic reaction. [38]

In case of chronic or recurrent course, ineffectiveness of basic topical therapy, frequent skin infections or suspicion of a contact component, consultation with a dermatologist and allergist is recommended to clarify the diagnosis and examination plan. [39]

In drug-induced dermatoses, it is important to link the onset of the rash to the medication as early as possible, discontinue it, and seek an assessment of its severity and treatment options. Documenting the reaction reduces the risk of recurrence in the future. [40]

Diagnostics

The first step is clinical verification of the phenotype during a consultation: a detailed interview about the onset, dynamics, triggers, skin care, family history of atopy, concomitant diseases, medications, and food reactions, as well as an examination assessing the distribution and morphology of the rash. Validated severity and pruritus scales are used for atopic dermatitis. [41]

The second step involves basic exclusionary tests as indicated. For urticaria, routine, comprehensive panels are often not required; a limited examination focused on the anamnesis is sufficient, with the understanding that extensive screening has a low diagnostic value in many children. For induced forms, standardized provocative tests are used. [42]

The third step is allergy diagnostics if specific triggers are suspected. For allergic contact dermatitis, the "gold standard" is patch testing with age-specific panels and exposure considerations. For food or inhalation sensitization, skin prick tests and allergen-specific immunoglobulin E measurements are used, but the results are interpreted in a clinical context. [43]

The fourth step is differential verification and monitoring of complications. For frequent skin infections, the need for cultures and adjustments to care is assessed. For severe or resistant forms, a skin biopsy and an expanded laboratory panel are considered to exclude mimics and systemic causes. Regular reassessment of the diagnosis is essential. [44]

Table 3. Diagnostic algorithm for practice

Stage	What are we doing?	For what
Clinic	Detailed history and examination	Determine phenotype, severity, triggers
Basic tests	Limited tests according to indications	Rule out obvious systemic causes
Allergy diagnostics	Application tests, prick tests, specific immunoglobulins of class E	Confirm causal triggers
Provocations	Standardized tests for induced urticaria	Confirm the diagnosis and degree of sensitivity
Revision	Reassessment and monitoring of complications	Correction of the plan and prevention
Source: International guidelines on atopic dermatitis, urticaria and contact dermatitis. [45]

Differential diagnosis

Atopic dermatitis is differentiated from seborrheic dermatitis in infants, scabies, mycoses, immunodeficiencies, and hereditary keratinization disorders. Suspicion is heightened by atypical localization, lack of response to standard care, and frequent severe skin infections. [46]

Urticaria is distinguished from urticarial vasculitis, mastocytosis, drug-induced rashes, and viral rashes. Signs that urticaria does not develop include painful lesions, persistent rashes in one area for more than 24 hours, and pigmentation after resolution. In cases of angioedema, hereditary angioedema is ruled out. [47]

Allergic contact dermatitis must be distinguished from irritant contact dermatitis, atopic dermatitis, seborrheic dermatitis, and mycoses. Patch testing helps identify sensitization and delineate the underlying mechanism. [48]

Drug-induced dermatoses are timed to coincide with the start of therapy, and infectious and autoimmune causes are excluded. If in doubt, a consultation with a specialist and discussion of a biopsy are recommended. [49]

Treatment

The basis for all phenotypes is barrier restoration and itching control. Daily warm, short baths followed by generous application of emollients, gentle skin drying, and the use of mild detergents and cotton clothing form the basis of care and reduce the frequency of flare-ups. Family education improves adherence. [50]

Topical anti-inflammatory therapy includes topical corticosteroids of varying potency depending on location and age, and calcineurin inhibitors for sensitive areas and to maintain remission. Proactive regimens with infrequent application to problem areas are used to prevent relapse. Proper selection of class reduces the risk of side effects. [51]

For moderate to severe atopic dermatitis that is not adequately controlled with topical therapy, phototherapy and systemic agents are used. Current guidelines support the use of biologics and Janus kinase inhibitors in adolescents and, where approved, in younger children, with strict monitoring of efficacy and safety. [52]

Urticaria is treated stepwise: initially, non-sedating second-generation antihistamines are administered daily at a standard dose. If the effect is insufficient, the daily dose can be increased by a multiple of this amount under the supervision of a physician. If resistance develops, antileukotriene agents and a transition to biological therapy are considered. Glucocorticosteroids are used for a short course and only for the relief of severe exacerbations. [53]

For chronic spontaneous urticaria in adolescents and in severe cases, omalizumab is added according to protocol, focusing on the safety profile and local approvals. In complex cases and if the chosen strategy is ineffective, cyclosporine is considered with careful monitoring. Regular review of triggers is mandatory. [54]

Allergic contact dermatitis is treated by eliminating allergens and inflammation. Effectiveness is achieved through a combination of avoiding contact, topical corticosteroids based on the area and age, barrier restoration agents, and short courses of antipruritic medications. Patch testing guides further prevention and the selection of safer alternatives. [55]

Skin drug reactions require immediate discontinuation of the suspected drug and symptomatic therapy. Severe reactions require hospitalization. Documentation of the reaction and family education help prevent recurrences and inadvertent rechallenge. [56]

A supportive strategy includes proactive care, environmental control, minimizing contact with known allergens, preventing scratching, and training in recognizing early signs of flare-ups. A written action plan simplifies home management. [57]

Table 4. External therapy and care

Direction	Examples of solutions	Comments
Care	Daily emollients, mild detergents	The basis for all phenotypes
Inflammation	Topical corticosteroids by potency class	Taking into account age and zone
Alternative and maintenance	Calcineurin inhibitors	For sensitive areas and proactive schemes
Antipruritic measures	Cooling lotions, antihistamines as indicated	Symptomatic support
Source: Pediatric guidelines for atopic and contact dermatitis. [58]

Table 5. Steps of treatment for urticaria in children

Step	Action	Target
1	Second-generation daily non-sedating antihistamines	Symptom control
2	Increase the dose under the supervision of a physician	Overcoming resistance
3	Addition of biological therapy in adolescents, consideration of immunomodulators	Stable remission
Urgently	Short course of glucocorticosteroids	Rapid relief of severe exacerbation
Source: International Urticaria Guidelines. [59]

Table 6. When to consider escalating therapy in atopic dermatitis

Situation	What to change
Frequent exacerbations despite optimal care	Assess adherence, strengthen topical therapy
Sleep and learning disorders	Consider phototherapy and systemic options
Severe itching with scratching and infection	Escalation to targeted therapy if indicated
Source: Current guidelines on atopic dermatitis. [60]

Table 7. Management of allergic contact dermatitis

Stage	Actions
Confirmation of the reason	Application tests with priority panels for children
Elimination of contact	Finding safe alternatives and educating families
Treatment of exacerbation	Topical corticosteroids, barrier care
Prevention	Checking the composition of cosmetics, toys, and accessories
Source: Systematic guidelines and registries on childhood contact dermatitis. [61]

Prevention

Daily skin care with emollients, avoiding harsh cleansers, and active moisturizing reduces the frequency of atopic dermatitis flare-ups. Learning proper bathing, drying, and emollient application techniques significantly improves disease control. [62]

To prevent contact dermatitis, it is important to avoid frequent and prolonged contact with known allergens. Parents are advised to check the ingredients of cosmetics and household chemicals for preservatives and fragrances, limit exposure to nickel, and choose hypoallergenic alternatives. [63]

For urticaria, reducing exposure to physical triggers and avoiding triggers can help reduce the frequency of episodes. For induced forms, specific protective measures, chosen after confirming the trigger, are helpful. [64]

A written self-care plan, timely adjustments to therapy at the first signs of exacerbation, and regular communication with the treating physician reduce the severity of the disease and the risk of hospitalization. Family education is key to sustainable results. [65]

Forecast

Most children with atopic dermatitis achieve satisfactory control with proper care and timely escalation of therapy. Some patients outgrow the disease by adolescence, but effective modern treatments are available for those who remain active. [66]

Acute episodes of urticaria are usually self-limited; chronic forms require a systemic approach and can last for months or years, but with proper treatment and appropriate stepwise therapy, sustained remission can be achieved. Biological agents have significantly improved outcomes in resistant patients. [67]

Allergic contact dermatitis has a favorable prognosis with complete allergen avoidance and proper care. Persistent forms are associated with continued exposure, so accurate identification of the trigger using patch testing remains key. [68]

The long-term burden of allergic dermatoses is reduced with multidisciplinary management, including a dermatologist, allergist, and trained medical teams. Regular reassessment and individualization of the plan improve the sustainability of remission. [69]

FAQ

Is it permanent, or can you "outgrow" allergic dermatitis?
Many children improve over time, but some remain prone to dryness and flare-ups. Early intervention and proper step-by-step therapy increase the chances of long-term remission. [70]

Should a "test for everything" be done for urticaria?
No. For most children, a limited examination focused on the anamnesis is sufficient. Broad panels without indications are rarely helpful and can be misleading. [71]

Are hormonal ointments dangerous?
When the class, area, and frequency of application are chosen correctly, topical corticosteroids are safe and effective. The doctor's job is to select the minimum dosage and explain the application instructions. [72]

How can you tell if your child has contact dermatitis?
Suspicion arises when the rash is clearly associated with specific objects and areas of contact. Patch testing with priority childhood allergens confirms the diagnosis. [73]

When should biological agents be considered?
In moderate to severe cases not controlled by optimal care and topical therapy, after discussing the indications, contraindications, and monitoring. This is especially relevant in adolescents, according to current guidelines. [74]