Atopic dermatitis

Clinical picture and diagnostic triad

To establish a diagnosis, it is fundamentally important to identify three basic characteristics that make up the classic triad of signs of the disease:

1. Obligatory presence of itching. Skin itching (pruritus) is the main symptom, without which the diagnosis is called into question.
2. Chronic relapsing course. The pathology proceeds in waves, with periods of exacerbation alternating with periods of remission. Clinical forms can be either acute or chronic, as clearly demonstrated by typical skin rashes.
3. Age-related evolution. The morphological picture and localization of lesions change predictably depending on age. For example, exudation is more common in infants, whereas lichenification (thickening of the skin with enhanced markings) is more common in older children.

Epidemiology and social significance

This pathology is one of the most frequent allergic pathologies in pediatrics. In the global structure of allergic diseases, it accounts for 20 to 73%. The peak incidence occurs at an early age, after which rates gradually decrease as patients grow older:

• 1st year of life: prevalence is 5.5–30.8%.
• 6–7 years: rates drop to 9.0–28.5%.
• 13–14 years: registered in 6.7–20.7% of adolescents.

Despite the fact that the onset of pathology occurs in infants in 80% of cases, the prognosis is considered generally favorable. In the majority of patients, spontaneous remission is observed after five years of age. Nevertheless, the pathology has a tendency to persist and can continue continuously or relapse in adulthood, bringing severe discomfort to the patient and their family members.

Atopic march

The disease rarely occurs in isolation. The foundation for its development is a hereditary predisposition, and skin manifestations often become only the first stage of the so-called "atopic march". Subsequently, the process can be combined with other allergic pathologies, such as bronchial asthma, allergic rhinitis, allergic conjunctivitis, and food allergies.

Evolution of sensitization and main triggers

The etiological structure of the disease is not static; it undergoes predictable changes as the child grows.

At the initiating stage (at an early age), food sensitization acts as the main trigger factor. The most clinically significant triggers here are cow's milk proteins, chicken eggs, and gluten (as well as wheat, soy, peanuts, and fish).

At the broadening spectrum stage (at an older age), a chronic disruption of the skin barrier function occurs. Due to damage to the epidermal barrier, new allergens join in and new effector zones become involved. Added to food allergens are:

• Aeroallergens: tree and grass pollen, indoor house dust mites, epidermal allergens (animal dander), mold spores, and cockroach particles.
• Bacterial agents: streptococci and toxins of Staphylococcus aureus.
• Fungal agents: yeast-like fungi of the genera Candida and Malassezia (including Malassezia furfur / Pityrosporum ovale).

Class and exam questions

What else to study on this topic

• Morphological picture of the rash: what exudation and lichenification look like
• The role of epidermal barrier dysfunction in the pathogenesis of allergic dermatoses
• Staphylococcus aureus toxins as bacterial agents of inflammation
• The concept of the "atopic march" and its connection with bronchial asthma
• Food sensitization in infants: cow's milk proteins and gluten

Other topics in "Chapter 5. Allergic Diseases"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.