Prurigo

Two principal varieties of prurigo are distinguished: infantile (prurigo infantum, seu strophulus) and adult (adultorum). A less frequent variety is nodular prurigo (prurigo nodularis).

Prurigo nodularis is a disease well defined clinically and histopathologically. The morphological lesions are semispherical hard pustules, 5-12 mm in diameter, often with a verrucose surface. They are usually localized on the extensor surfaces of the lower limbs and less frequently on the upper limbs and trunk. The disease greatly resembles the hypertrophic form of lichen rubrum planus. It is mainly encountered among middle-aged females and is characterized by a protracted chronic course. Emotional stress and mosquito bites are among the causative factors noted. A very severe and persistent itching leads to changes in the nerve receptors.

Treatment. Some pruriginous nodular lesions are destroyed by means of liquid nitrogen, carbon dioxide or diathermocoagulation. Antihistaminic agents and sedatives are prescribed at this time.

Infantile prurigo (syn. strophulus, papular urticaria in children, infantile urticaria) prevails among children of 5 months to 3 years of age suffering from exudative diathesis. It usually sets in during the first year of life. An important role in its pathogenesis is played by sensitization to food: to the protein of the mother's or cow's milk (caseinogen) in infants. Exacerbation of the disease in older children is usually attributed to chocolate, canned foods, citrus fruit, eggs, less frequently to mushrooms, strawberries, some kinds of fish and other products, and sometimes to drugs.

Besides sensitization to food and drugs, autotoxicosis and autosensitization from the intestine play a definite role in the development of prurigo.

Clinical picture. In addition to itching, which usually occurs in paroxysms the child develops diffuse papulovesical or, less frequently, urticarial-macular eruptions on the face, scalp, trunk, buttocks and extensor surfaces of the limbs. The mucous membranes are not involved. Papular lesions with vesicles on their tops are the most typical, punctate erosions and serous crusts come next.

In many children prurigo disappears after they are weaned. Less frequently it develops into chronic prurigo of adults, pruriginous eczema or diffuse neurodermitis (atopic dermatitis). Such children with persistent prurigo have white dermatographia, a marked neurotic state, dry skin, disturbed sweat secretion, and enlarged lymph nodes (inguinal and femoral in particular).

Diagnosis. Prurigo is distinguished from neurodermitis only by certain morphological features of the eruption and its localization: in neurodermitis the eruption prevails on the flexor surfaces of the limbs, whereas in prurigo it is found on the extensor surfaces. Differential diagnosis is also made with scabies and drug disease.

Treatment. Dietetic treatment is very important. The diet for children calls for particular scrupulousness. Before all else, the child should not be overfed, and carrot juice, yoghurt and cottage cheese should be given as early as possible, gradually increasing their amount.

Vegetables (carrots, cabbage, spinach, peas, sorrel) and fruits are given in abundance. Sour dairy foods (yoghourt, kefir, sour milk) and cooked meat (lamb and beef) are recommended. Vegetable oil is given. The food should be sparce in salt, with no excess of carbohydrates or fats, it should be rich in vitamins C, B and A, with a sufficient amount of vegetables.

All food listed above and other foodstuffs, which induce exacerbation of a pruritic allergic dermatosis, are removed from the diet of infants of nursery, pre-school and school age.

Expectant mothers and mothers in the period of lactation are not allowed eggs, fish, citrus fruit, strong meat broth and pork; salty foods and fats should be restricted. Vegetables and fruits should be given in abundance. Sour dairy foods and boiled beef are recommended.

Test for helminths must be conducted and if these are detected not only children, but also expectant and nursing mothers must be treated, because helminths, nematode worms in particular, cause a strong allergenic effect. Special care should be accorded to the detection of various foci of infection (chronic tonsillitis and cholecystitis, sinusitis, otitis, carious teeth, etc.) in patients with exudative diathesis. Obligatory and timely treatment of these foci reduces the possibility of the development of infectious allergy and auto-allergy.

Children with prurigo are given antihistaminic and neuroplegic agents, sedatives, vitamins of the B complex and vitamin A, rutin, ascorbic acid. Calcium preparations are advisable in vagotonia (red diffuse dermatographia, which is often of a stable character). Corticosteroid hormones are used in low and gradually reduced doses in particularly persistent cases.

Ultraviolet irradiation with suberythema doses (every other day to a total of 20 exposures) are among the indicated physiotherapeutic methods. Older children are treated by lumbar inductothermia. In the absence of pyococcal infection, a favourable effect is caused by baths with decoctions of bur-marigold or oak bark, chamomile and sometimes with bran. Sea bathing is beneficial.

External treatment is of an auxiliary character and is applied only in combination with a rational diet and general therapeutic measures. Ointments and creams with corticosteroid hormones and aqueous-zinc shake lotions with glycerin are prescribed.

The pustules are opened and painted with a 1-2 per cent solution of aniline dyes, 1-2 per cent potassium permanganate solution or a 5-10 per cent silver nitrate solution. If crusts (purulent or seropurulent) have formed, ointments like Oxycort, Cremgen, Celestoderm with garamycin, Locacorten or ointments with vioform, neomycin are prescribed.

Prurigo of adults (prurigo adultorum, seu temporanea) is manifested by itching and papular eruptions mainly on the extensor surface of the limbs as well as on the back, abdomen, loins, and buttocks. The flexor surface of the limbs and face is usually not involved in the process. The papules are scattered, hard in consistency, conic or semispherical in shape (ranging in size from a pin-head to a millet or hemp grain). They are pinkish-red and may have hemorrhagic crusts on their surface as the result of excoriations. Because of oedema some papules acquire an urticarial appearance. Pustules form if secondary pyococcal infection develops. The disease lasts from several weeks to many months. Neurotic disorders and troubled sleep develop in chronic prurigo. Such patients have enlarged lymph nodes and eosinophilia.

Treatment of patients with prurigo is the same as for diffuse neurodermitis.