Microbial Eczema

The etiology and pathogenesis of microbial (paratraumatic, localized around the wound) eczema, in distinction from those of true eczema, have been studied sufficiently. It is considered established that the antigenic properties of pyococcal flora and pathogenic fungi, yeasts included, are capable of sensitizing the skin to these allergens. Neuroendocrine disorders and changes in metabolic processes and immunological states favor the development of sensitization to the microbial antigen.

These causes are responsible for the development of the peculiar clinical picture of microbial eczema, which differs considerably from that of the other forms of eczema. Microbial eczema usually begins as an asymmetric process on the legs, the back of the hands, and the scalp. There is a characteristic sharply demarcated focus of affection often with a fringe of separating epidermal horny layer on the periphery and a weakly pronounced tendency of the dermatosis to disseminate. The borders of the foci (acute inflammatory erythema, exudative papules, microvesicles, pustules) are often curved and there are accumulations of greenish-yellow seropurulent and sanguineous crusts and erosions on their surface.

On areas free of crusts the affected surface is red or congestive-red and bleeds easily. Punctate weeping (serous or eczematous wells) which is characteristic of eczema are seen here and there. Exacerbations of the disease occurring from time to time lead to intensification of itching.

Microbial eczema often sets in with pustules, acute inflammatory erythema and exudative papules, which appear on the periphery of a trophic ulcer on the leg, in the region of a postoperative stump, around a fistula; it may also develop as the result of improper application of a plaster cast, inadequate treatment of the skin around a wound with iodine tincture, and other factors. In such cases microbial eczema is called paratraumatic or eczema arising around a wound. Several varieties of microbial eczema are known.

Nummular eczema This form is characterized by mildly elevated and sharply demarcated foci of affection with regular round contours and a diameter of 1-2 cm and more; there are oedema, erythema, exudative papules and pronounced drip weeping. It is a variety of microbial eczema. The process tends to spread to the skin on the trunk and the limbs, although its favourite localization is the dorsal surface of the hands. The disease tends to recur and is highly resistant to treatment.

The frequent appearance of secondary allergic eruptions, the morphologically pleomorphic microbids, during exacerbation of the process is also characteristic of microbial eczema. These are usually erythematous scaling spots or papular and papulovesicular eruptions which are accompanied with intensive itching. In some cases (in growth of sensitization) they may transform to true eczema with the formation of very many rapidly rupturing microvesicles and punctate erosions with drip weeping (serous or eczematous wells).

Varicose eczema. The varicose complex of symptoms in the lower limb facilitates the development of this disease. It is localized in the region of the varicosity, around the varicose ulcers, and in the areas of sclerosed skin. Factors favoring the development of the disease are injuries, hypersensitivity to drugs used in the treatment of varicose ulcers, and maceration of the skin in application of dressing. The clinical picture is characterized by pleomorphic lesions, sharply circumscribed boundaries of the foci, and moderate itching, which makes varicose eczema similar to microbial and paratraumatic forms in clinical manifestations.

Sycosiform eczema. This form may be encountered in individuals suffering from sycosis complicated by eczematization. Follicular pustules pierced through the middle by a hair shaft develop on inflamed skin and recur from time to time; these are symptoms of sycosis. Sycosiform eczema is characterized by extension of the process beyond the hirsute areas, the presence of eczematous wells, weeping and severe itching. Lichenification of the skin occurs and follicles appear incessantly. The favoured localization of the process is the upper lip, the beard, the axillae and the pubis.

Eczema of the nipples and the areola of the breast in females. The characteristic lesions are crimson foci covered in places with layers of crusts and crusty scales and marked by weeping and cracks. The process is sharply circumscribed and very persistent. Eczema of the nipples is often a consequence of injuries inflicted during breast-feeding or results from complicated scabies.