Prurigo is an itchy dermatosis, the main elements of the rash in which are small nodules with small bubbles in the center. Pronounced itching leads to scratching of rash sites and the appearance of deep excoriation. A distinctive feature is the location of the rash on the extensor areas of the limbs without involving the flexor surfaces. Diagnosis is carried out by dermatological examination, examination of the gastrointestinal tract and exclusion of similar skin diseases. Treatment consists in the appointment of a diet, vitamins, physiotherapy, antihistamines and sedatives.
Modern dermatology distinguishes three clinical varieties of prurigo: adult prurigo, pediatric and nodular prurigo. Childhood form develops mainly during the first year of a child’s life, but can occur in children under 5 years of age. Elderly people suffer from adult form. Nodular prurigo is observed, as a rule, after 50 years and more often in women.
The main cause of the development of prurigo is considered to be sensitization of the body, leading to the development of allergic inflammation processes in the skin. The main sensitizing agents include food products. In infants, this is cow’s or mother’s milk protein, at an older age — mushrooms, flour products, eggs, citrus fruits, chocolate, strawberries, some types of fish. In adults, smoked meats, honey, coffee, alcohol, spicy foods and spices can act as food sensitizers.
Of great importance in the development of prurigo in children is a constitutional tendency to allergic reactions, manifested in the form of exudative diathesis, as well as various fermentopathies of the digestive tract. The predisposing factor, both in children and adults, may be autosensitization and autointoxication of the body from the intestine with dysbiosis, helminthic invasion, biliary dyskinesia. In adults, the provoking factors in the development of prurigo may be neuropsychiatric disorders (sleep disorders, neurasthenia) and some general diseases (diabetes mellitus, tumors of internal organs, lymphogranulomatosis, chronic hepatitis, cirrhosis of the liver, cholecystitis, etc.).
According to some authors, the occurrence of prurigo is caused by insect bites (mosquitoes, ticks, fleas) and the disease should be attributed to epizoonosis. This hypothesis is confirmed by the high prevalence of the disease in rural areas, its seasonality and the positive results of an allergic test with insect antigens in the majority of patients.
Children’s prurigo begins with the appearance on the skin of scattered and abundant rashes in the form of nodules of 3-5 mm in size, on the surface of which small bubbles appear over time. The bubbles burst with the formation of point erosions covered with serous crusts. Along with the presence of a rash on the skin of the trunk and face, the location of a large number of rashes on the extensor surfaces of the limbs is typical. Papulovesicles can be located on the skin of the palms and soles. At the same time, they have a larger size (5-7 mm), an edematous base and an inflammatory rim. A distinctive feature is intense itching. As a result of combing, multiple excoriations appear in the places of rashes.
In children with prurigo, along with rashes, neuropsychiatric disorders are observed: capriciousness, poor sleep, tearfulness, increased irritability. These symptoms can be caused both by the disease itself (severe itching and auto-intoxication of the body), and by the congenital lability of the nervous system as a result of the peculiarities of the constitution.
In many cases, there is an independent regression of the symptoms after the exclusion of cow’s milk and infant formula from the child’s diet. But there may be a transition of childhood prurigo into atopic dermatitis, pruriginous eczema or adult prurigo. Signs of such a transformation are the appearance of white dermographism, a decrease in the abdominal reflex and the disappearance of the plantar. Such children have dry skin, anhidrosis, enlarged femoral and inguinal lymph nodes.
Adult prurigo is characterized by intensely itchy nodular rashes on the skin of the abdomen, buttocks, back and extensor surface of the arms and legs. The face and flexor surface of the limbs are usually not affected. Dense hemispherical or conical papules of brownish-red color up to 5 mm in size are typical for adult prurigo. Along with this, papules may be observed, characterized by a bright red color and the most severe itching. There are multiple excoriations covered with hemorrhagic crusts.
Adult prurigo can have an acute and chronic course. In the latter variant, the neurotic syndrome gradually joins the skin symptoms: sleep disorders, irritability, pronounced emotional lability.
Nodular form is characterized by a chronic and prolonged course. Rashes are represented by dense hemispherical papules. Their size ranges from 6 to 15 mm. With nodular prurigo, rashes are located mainly on the skin of the extensor surface of the legs, less often on the arms and trunk. Infection of the elements of prurigo during combing can often lead to the development of ostiofolliculitis, folliculitis, pyoderma or furunculosis.
When diagnosing prurigo, a dermatologist should conduct an examination and dermatoscopy of the rash. If a secondary infection is suspected, a back-up scraping is carried out to identify the pathogen and its sensitivity to antibacterial drugs. The occurrence of prurigo on the background of gastrointestinal disorders or endocrine pathology requires consultation with a gastroenterologist or endocrinologist. A study of feces for helminth eggs and an analysis for dysbiosis is being carried out. If necessary, patients with prurigo are prescribed ultrasound of the liver and pancreas, liver tests, examination of pancreatic enzymes.
An important point in the diagnosis of prurigo is the exclusion of dermatological diseases that have a similar clinical picture. The location of the rash and the morphological features of the elements of prurigo in most cases make it possible to distinguish it from atopic dermatitis, scabies and toxicoderma.
In atopic dermatitis, unlike prurigo, rashes are localized on the flexor surfaces of the extremities. With scabies, dermatoscopy allows you to detect typical moves, and a positive test result for scabies confirms the diagnosis. Toxidermy is characterized by a connection with rashes with the use of medications. Nodular prurigo must be differentiated from red lichen planus.
An important place in the treatment of prurigo belongs to the diet. In infants, to reduce the sensitization of the body to breast milk, it is recommended to give 10 drops of expressed milk 15 minutes before feeding. With prurigo, it is necessary to include cottage cheese, kefir and carrot juice in the diet earlier. Pregnant and lactating women should avoid consuming large amounts of citrus fruits, eggs, fish, pork, pickles.
For older children and adults suffering from prurigo, sour-milk products (ryazhenka, cottage cheese, kefir), boiled beef, sunflower oil, fruits and vegetables (especially carrots, cabbage, spinach and peas) are recommended. When helminthic invasion is detected, deworming is carried out. It is also necessary to sanitize foci of chronic infection: carious teeth, otitis, sinusitis, chronic tonsillitis, treatment of gastrointestinal diseases and dysbiosis.
In the treatment of prurigo, digestive enzymes (pancreatin, etc.), B vitamins, vitamins A and C, antihistamines (fencarol, loratadine, desloratadine, clemastine, chloropyramine, etc.), calcium preparations and sedative medications (peony tincture, valerian) are used. Therapeutic baths with bran, decoction of oak bark, turn or chamomile have a good effect. As an additional remedy for prurigo, it is possible to use ointments and creams with glucocorticoids. In severe cases, small doses of glucocorticosteroids are prescribed orally.
Of the physiotherapeutic methods for prurigo, suberythemic doses of UVI, electroson, phonophoresis with hydrocortisone, inductothermy, microwave therapy on the adrenal region, medicinal electrophoresis, DDT on the cervical sympathetic nodes are used.