Pemphigus foliaceus

Pemphigus foliaceus is an autoimmune blistering disease of the skin. The immune system attacks the subcorneal layer of the epidermis, producing lesions that appear as scaly or crusted erosions on a red base. Unlike some other forms of pemphigus, the mucous membranes are not involved, even when the disease is widespread. Nearly all of the autoantibodies in the epidermis are directed against desmoglein 1, a protein that helps skin cells stick together. Three mechanisms are thought to explain the damage: the antibody may block the binding site on desmoglein 1, it may trigger the cell to take the protein inside and so lose adhesion, or it may stop desmoglein 1 from being built into a desmosome. Each route leads to loss of adhesion between skin cells, a change known as acantholysis.