Pityriasis alba (PA) is a common, benign skin disorder occurring predominantly in children and adolescents. It is characterized by ill-defined hypopigmented macules and patches, round or oval in shape. They are most commonly located on the face (especially the cheeks), arms, and upper trunk; and they are more noticeable in people with darker skin types. Sun exposure accentuates the lesions. Patients and their parents are often anxious about the cosmetic appearance of the lesions. PA is not seasonal, although peeling may be worse in the winter (as a result of dry air in homes) and lesions may be more obvious in the spring and summer (as a result of sun exposure and darkening of the surrounding skin).No specific cause of PA has been identified. It is not contagious, and no infectious etiology has been reported. It is most common in individuals with a history of atopy, although it may occur in nonatopic individuals.

In the present study, we will investigate the role of serum vitamin D levels and serum total IgE levels with development and course of PA. Plasma levels of 25(OH) vitamin D and Total serum immunoglobulin E will be determined by using ELISA technique.

The prospective cohort study will be conducted on the basis of Research Institute of Epidemiology, Microbiology and Infectious Disease, Ministry of Public Health of the Republic of Uzbekistan.

Both informed and written consents will be obtained from the parents or from appropriate relative or guardian of the patients and healthy individuals of the control group.

Study participants will be included about 30 children aged 5 to 12 years with pityriasis alba. The control group will be included about 20 healthy individuals. All the participants will be residents of Uzbekistan.

Diagnosis of pityriasis alba Diagnosis of pityriasis alba will be based on the results of clinical examination. Inclusion criteria: revealing multiple round or oval-shaped hypopigmented macules or patches with indistinct margins. A weak erythema may be observed in some patches. The lesions number could varied from four to ten, 0.5 cm - 5 cm in size, and they are distributed predominantly on the face, neck, upper arms, and upper trunk.

Exclusion criteria The exclusion criteria: chronic and acute infectious diseases, endocrine diseases, congenital diseases, allergic dermatitis, bronchial asthma, allergic rhinitis and/or conjunctivitis, other skin disorders, history of using vitamin D supplements within three months ago, or use of any medication influencing endocrine parameters.

Measurement of anthropometric indices Demographic data will be obtained in the survey included age, gender, and body mass index (BMI) calculated as weight (kg)/height2 (m2).

Sample Collection and Storage Five milliliters of peripheral venous blood sample will be taken (after 8-12 hours of fasting) from each participant and will be collected into HumaTube Serum Gel - C/A for ELISA. Serum will be appropriately obtained and stored at -20°C maximum of 30 days. All blood samples will be collected during summer period.

Estimation of Vitamin D and Total Immunoglobulin E Plasma levels of 25(OH) vitamin D (DIAsource kit, Belgium) and Total serum immunoglobulin E (HUMAN kit, Germany) will be determined using ELISA technique.

Classification of Vitamin D and Total Immunoglobulin E Serum vitamin D level will be classified as reported by Holick (Holick MF. 2007). Levels of vitamin D ≤20, 21-29, ≥30-150, and >150 ng/ml will be considered as vitamin D deficiency, vitamin D insufficiency, vitamin D sufficiency and vitamin D intoxication, respectively.

Normal levels of total immunoglobulin E for children 1-6 years old - <30 Ul/ml, 7-9 years old - <60 Ul/ml and 10-12 years old - <100 Ul/ml, 13-16 years old - <150 Ul/ml.

Inclusion Criteria:

• Patients with Pityriasis alba
• Healthy individuals (control group)

Exclusion Criteria:

• chronic and acute infectious diseases;
• endocrine diseases;
• congenital diseases;
• allergic dermatitis;
• bronchial asthma;
• allergic rhinitis and/or conjunctivitis;
• other skin disorders;
• history of using vitamin D supplements within three months ago, or use of any medication influencing endocrine parameters.

The prospective cohort study will be conducted on the basis of Research Institute of Epidemiology, Microbiology and Infectious Disease, Ministry of Public Health of the Republic of Uzbekistan. All participants will be residents of Uzbekistan.

Diagnosis of pityriasis alba will be based on the results of clinical examination.