Non-infectious dermatoses

Allergodermatoses are quite common and are caused mainly by contact of the population with plants and their products. They are called plant dermatitis (forest, jungle). The most common are mango, pineapple, primrose, polyandre, beech, tobacco, poison ivy, etc., phytodermatitis.

Tropical lichen planus

A disease characterized by the appearance of rashes on exposed skin areas that are clinically and morphologically similar to classic lichen planus. The onset of the disease is associated with the use of the antimalarial drug atebrine, high air temperatures, long daylight hours, increased solar radiation, alimentary dystrophy (children), vitamin deficiencies, helminthic invasions, and baking bread using a tandoor. The disease usually occurs in the summer months. The face (forehead, cheeks, lips), exposed areas of the neck, the back of the hands and lower thirds of the forearms, and the back of the feet are affected. Lesions of the oral mucosa may occur, such as leukoplakia, the formation of vesicular-erosive lesions, and stomatitis. Skin lesions are practically indistinguishable from typical rashes of lichen planus (with the presence of Wickham mesh). By winter, inflammatory phenomena and itching regress; persistent hyperpigmentation remains at the site of the rash.

Treatment: exclude the use of atebrine or replace it with another antimalarial drug. Skin protection from high air temperature and solar radiation is necessary. Hyposensitizing and other symptomatic agents are prescribed.

Prognosis: favorable in most cases, but relapses are possible.

Eczema

A weak exudative reaction (microvesiculation, oozing) is characteristic, more reminiscent of neurodermatitis, i.e. a “dry” course of the eczematous process.

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Neurodermatitis

It is characterized by a tendency for rashes to disseminate and undergo weak lichenification.

Psoriasis

In tropical conditions it is observed less frequently. More common are infiltrative forms of dermatosis in the form of single, "on-duty" dry plaques in places of favorite localization. Isomorphic reaction is not typical. Histological examination is often required to confirm the diagnosis.

Erythematosis

Chronic skin forms of the disease are much less common (despite hyperinsolation) than in countries with moderate and cold climates. Systemic lupus erythematosus is diagnosed somewhat more often than in European countries.

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Tropical pruritic dermatoses

Temporary pruritus - the appearance of itchy small serous papules on the extensor surfaces of the extremities, which subsequently become covered with serous-hemorrhagic crusts. The process can last up to several months with flu-like symptoms. The course of the disease is aggravated by helminthic invasions and other concomitant diseases.

Tropical miliaria is a temporary dermatosis associated with the blockage of sweat glands (horny scales, sebum, dust, etc.) at different levels of their occurrence in the skin when working in hot conditions: from transparent bubbles filled with sweat to their pustulation. The process is most often localized in the elbow and knee folds, on the chest, abdomen, other areas, rarely on the face. It disappears on its own with a change in climate.

Tropical pompholyx - is seasonal (summer). Symptoms of miliaria occur only on the palms and soles of the feet, lateral surfaces of the fingers. Intraepidermal vesicles open, erode, then quickly epithelialize, without causing subjective complaints. Complications - eczematization, pustulization, abscess formation.

Phlebotoderma is a common dermatosis that occurs after repeated mosquito bites and sensitization of the body to the secretion of the salivary glands of phlebotomuses. On open areas of the body, soon after the attack of mosquitoes, roseola with a punctate hemorrhage in the center appear, then turning into itchy papules, often covered with blisters. Water-drying and papulobullous reactions are possible. The appearance of elements is accompanied by excoriations. After an attack of phlebotomuses, the process usually gradually subsides. Depending on the degree of sensitization, the presence of concomitant diseases with repeated attacks of mosquitoes, the dermatosis can take on a widespread recurrent nature with the formation of pruriginous nodular elements (up to a pea), various pyococcal rashes. The disease can drag on for several months or longer. In some cases, it is necessary to carry out active therapy, including the systemic use of corticosteroids.

Harara (endemic urticaria multiforme) is a seasonal (summer) itchy dermatosis associated with repeated bites of humans by certain species of mosquitoes. It is more common in Arab countries, both among visitors and locals (of both sexes and different ages). It is observed on exposed areas of the body, especially on the lower third of the shin and the back of the feet. The rash is polymorphic: papulo-blisters, serous papules, erosions, serous-hemorrhagic crusts, pyogenic elements. General toxic effects are possible. Over time (1-3 months), the process becomes "dry", gradually subsides, and temporary hyperpigmentation forms at the sites of the rash. In some cases, the disease can last up to 1-2 years (chronic harara) with a clinical picture of dry itchy nodular rashes and lichenification.

Tropical bullous dermatoses

True pemphigus is less common in tropical countries than in temperate and cold climates.

Tropical bullous dermatoses include Brazilian exfoliative pemphigus (BEP) and onyalai.

BEP - without prodrome on the face, chest, less often on other areas, blisters appear, which are complicated by the pyococcal process, eczematization, sometimes warty growths, focal dyschromia. Nikolsky's symptom is positive. The oral mucosa is not affected. A severe course is observed in fulminant (often fatal) and acute forms of BEP (signs of severe intoxication, extensive erosions and areas of impetiginization).

Symptoms are less pronounced in the subacute form of the disease. Chronic BEP has a long course and is accompanied by clinical polymorphism with the involvement of the musculoskeletal system, teeth, muscle atrophy, mammary glands and other manifestations.

Onyalai is a severe disease of hot countries with clinical features of bullous and hemorrhagic rash on the skin and mucous membranes. Systemic hemorrhagic syndrome, thrombocytopenia, severe general condition and formation of large blisters on the mucous membranes of the oral cavity with purulent deposits resembling aphthae are characteristic. The prognosis is unfavorable in the absence of intensive therapy, including corticosteroids, blood transfusions, blood substitutes.

Skin neoplasms

There is no consensus among researchers on the higher frequency of benign and malignant skin neoplasms in hot climates. There are data on rare cases of skin cancer in the population of China, Japan, Arab countries, and blacks. Penile cancer is not detected in peoples who traditionally perform excision of the foreskin. In Africans, skin cancer develops mainly at the sites of chronic inflammation, ulcers, and wounds. Vascular nevi in people of the black race are often poorly visualized, and hairy nevi are less common than in Europeans. No special features are noted in terms of the profile of benign neoplasms (warts, pointed condylomas, fibromas, etc.).

Lack of vitamins

Hypovitaminosis A is quite common, the skin lesions are widespread or universal. It responds well to correction with vitamin A.

Exfoliative cheilitis (associated with ariboflavinosis) is characterized by resistance to therapy.

Venereal diseases and endemic treponematoses

Venereal diseases

In people living in hot climates, the clinical manifestations and diagnosis of syphilitic infection have some peculiarities:

• roseola is poorly visible on dark skin;
• in the presence of ulcerative chancre, lymphadenitis is moderately expressed;
• in the later stages, periarticular nodules appear (elbows, knees);
• When diagnosing syphilis, it is necessary to take into account the possibility of false positive reactions associated with other infectious diseases (leprosy, malaria, helminthiasis, etc.) and drug use.