Subcorneal pustulosis: causes, symptoms, diagnosis, treatment

Subcorneal pustulosis of Sneddon-Wilkinson is a chronic relapsing disease that occurs more often in women over 40 years of age.

Synonym: Sneddon-Wilkinson disease

The disease was first described in 1956 by English dermatologists Sneddon and Wilkinson. Until recently, the literature discussed the question of whether the disease is an independent nosological form of dermatosis or whether pustular psoriasis, Hebra's herpetiform impetigo, pustular form of Duhring's dermatitis and a number of other skin diseases are hidden under its mask.

The causes and pathogenesis of subcorneal pustulosis are unknown. Concomitant infections, immunological and endocrine disorders play an important role in the development of the disease.

Symptoms of subcorneal pustulosis. The onset of the disease is sometimes associated with hormonal disorders accompanying thyrotoxicosis, pregnancy and childbirth, in some patients - with mental trauma. The skin of the trunk and proximal parts of the extremities is mainly affected. The rash is represented by pustules surrounded by a narrow rim of hyperemia, sometimes grouped. The pustules quickly open, and as a result, polycyclic erosions covered with crusts with fragments of pustule covers along the periphery predominate in the clinical picture. After healing of the erosions, hyperpigmentation often remains. The disease has a more benign course compared to other forms of generalized pustulosis, the condition of patients is disturbed insignificantly. A combination with gangrenous pyoderma has been described.

Subcorneal pustulosis is characterized by the formation of superficial pustules - phlyctenules, which arise on an erythematous base, tend to be grouped and herpetiform. The favorite localization of the rash is the skin of the trunk, limbs, inguinal and axillary folds. The pustule covers quickly burst, and their contents dry up into yellowish crusts, along the periphery of which there are scraps of the horny layer of the epidermis. After the elements resolve, pinkish and then weakly pigmented spots remain. Acantholytic cells are found in the contents of the phlyctenules. Nikolsky's symptom can be positive. The appearance of the rash and its further development is usually not accompanied by subjective sensations. Sometimes there is an inconstant and slight itching of the skin. Pustules are typically sterile. Mucous membranes are affected extremely rarely. The disease is long-term, with remissions. The general condition of patients is satisfactory. Exacerbations often occur in the summer.

Histopathology of subcorneal pustulosis. Pustules are located directly under the stratum corneum, which is most characteristic of this dermatosis. In the upper part of the skin itself, only the most insignificant phenomena of non-specific inflammation are noted.

Pathomorphology of subcorneal pustulosis. In the epidermis there is a slight acanthosis, areas of parakeratosis. Pustules are formed directly under the stratum corneum, contain neutrophilic granulocytes, fibrin, epithelial cells, single eosinophilic granulocytes and lymphocytes. They are usually unilocular. The pustule cover is formed by the parakeratotic stratum corneum, the bottom is the granular layer. Spongiosis and exocytosis are noted under the pustules. In the papillary layer of the dermis under the pustules there is edema and perivascular infiltrates consisting of lymphocytes, histiocytes, neutrophilic granulocytes and single eosinophilic granulocytes. In some cases, the pustules, increasing in size, can capture the entire thickness of the epidermis, sometimes penetrating into the dermis. Such pustules contain neutrophilic granulocytes and a large number of eosinophilic granulocytes. Bacteriological examination does not reveal any microorganisms in them. In old lesions, the epidermis is somewhat thickened, and clearly defined pustules filled with neutrophilic granulocytes and their enzymes are found under the well-preserved stratum corneum. The pustules affect only the superficial layers of the epidermis. Deeper, there is massive intercellular edema and penetration of individual neutrophilic granulocytes from the dermis; in the upper part of the latter, the capillaries are sharply dilated, severe edema and minor infiltrate are observed. Elastic and collagen fibers are without any particular changes.

According to the histological picture, subcorneal pustulosis differs from other generalized pustuloses by the location of the pustules, the absence of spongiform pustules of Kogoy and the limited inflammatory reaction of the dermis.

The histogenesis of the disease has been poorly studied. Significance is given to immune complexes found in the blood serum of patients. The disease can be provoked by drugs, infections and other factors, including tumors. Electron microscopic examination has shown that cytolysis of cells of the upper layers of the epidermis, especially granular, develops around the pustule, with the formation of subcorneal fissures. Along with the recognition of the independence of subcorneal pustulosis, there are opinions that it is one of the variants of pustular psoriasis, Duhring's dermatitis herpetiformis.

Differential diagnosis. The disease should be distinguished from the pustular variety of herpetiform dermatitis, herpetiform impetigo of Hebra, pustular psoriasis, pemphigus.

Treatment of subcorneal pustulosis. There are no effective therapeutic treatments. Antibiotics, sulfones, glucocorticoids, retinoids, phototherapy or a combination of phototherapy and retinoids are used. Aniline dyes and ointments containing corticosteroids and antibiotics are prescribed externally.

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