Pemphigus: Definition, Classification, Causes

What is Pemphigus

The term pemphigus identifies a group of bullous dermatoses with autoimmune etiology. These skin affections rare they are characterized by the appearance of lesions in the skin and mucous membranes.

Before the clinical and experimental understanding of its cause of origin, the term "pemphigus" was used to indicate indiscriminately any disease responsible for bullous lesions of the skin and mucous membranes.

Causes

Today we know that pemphigus is mainly due to the alteration of the cellular adhesion mechanisms of the epidermis; in particular, the disease is caused by the presence of specific autoantibodies (IgA or IgG) which attack a component of the desmosomes, damaging these structures (connection points) which tightly bind adjacent epidermal cells. The abnormal autoantibodies react with some glycoproteins present on the desmosomes of keratinocytes: desmogleins (Dsg); when the autoantibodies attack these components, the release of plasminogen (precursor of the plasmin protease) is induced, with consequent destruction of the intercellular bridges and lysis of the cells of the affected epidermal layer: the phenomenon is called acantholysis. Subsequently, the transudative liquid is recalled by osmotic diffusion, to form a characteristic swelling under the outer layer of the epidermis (bubble).