[Histological diagnosis of inflammatory skin diseases. Use of a simple algorithm and modern diagnostic methods].

The histological diagnosis of inflammatory skin diseases on a day-to-day routine basis poses the difficult task to characterise a dynamic clinical process by histomorphological analysis of one single lesion. Very complex algorithms which are meant to lead to the correct diagnosis are difficult to use. To facilitate the process and reduce the number of algorithms the following method is proposed: 1. Histological examination under low power Definition of lesions altered by scratching 2. Localisation of the significant pathological alterations as follows: Changes in epidermis and dermis Blister formation Changes in dermis/subcutis without characteristic changes in the epidermis Changes mainly in the subcutis 3. Closer examination using a simple algorithm and planning of further investigations following defined criteria: In the case of changes in epidermis and dermis definition of spongiotic, psoriasiform or lichenoid dermatitis (Abb. 1). In the case of blister formation definition of the blister following the given algorithm (Abb. 1). In the case of changes in dermis/subcutis without characteristic changes in the epidermis after exclusion of vasculitis and lymphoma definition of the main pattern as lymphocytic, neutrophilic, eosinophilic, lymphoplasmocytic or granulomatous and following the given algorithm (Abb. 2). In the case of changes mainly in the subcutis after exclusion of vasculitis and lymphoma definition of the main pattern of panniculitis as septal or/and lobular (Abb. 2). Exclusion of PAS positive microorganisms and checking if the general pattern fits into infectious correlation. Use of clinicopathological correlation.