In recent decades, the frequency of cases of widespread forms of pustular psoriasis has significantly increased, which are often mistaken for other chronic dermatoses: eczema, bullous toxidermia, herpes, Andrews’ pustular bacterid, subcorneal pustulosis, etc. – and as a result, late appointment of adequate treatment, severe course of the disease, possible fatal outcome.

The aim of the work is to analyze the histological features of widespread forms of pustular psoriasis depending on the clinical manifestations of dermatosis.

Materials and methods. 57 patients with pustular forms of psoriasis were under observation: 34 (60 %) patients with limited forms of pustular psoriasis, 23 (40 %) – with widespread forms (12 of them – with widespread and 11 – with generalized). All patients with widespread forms of pustular psoriasis underwent histological examination twice by punch biopsy: before the start of treatment and 7 days after the disappearance of pustular elements from the foci of background erythema. The obtained samples were stained with hematoxylin and eosin.

Results. When analyzing the clinical features of pustular psoriasis, it was found that a characteristic feature of widespread forms, in addition to multiple pustules, was persistent background erythema, which appeared in most patients at the beginning of the disease, persisted for a long time, even after the end of treatment, and the degree of its manifestations correlated with the severity of the disease. Histological analysis of the material taken from the foci of grouped pustules and background erythema revealed a relationship between the intensity of background erythema, the nature of morphological changes in the skin and the long-term prognosis of dermatosis.

Conclusions. Background erythema is an important diagnostic criterion for common forms of pustular psoriasis, characterizing the degree of neutrophilic infiltration of the skin, the risk of fresh pustules and the progression of dermatosis in general.