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INTRODUCTION
The term pemphigus stems from the Greek pemphix, meaning blister or bubble, and it describes a group of chronic blistering skin diseases in which autoantibodies are directed against the cell surface of keratinocytes, resulting in the loss of cellโcell adhesion of keratinocytes through a process called acantholysis. Pemphigus can be divided into three major forms: pemphigus vulgaris, pemphigus foliaceus, and paraneoplastic pemphigus (Table 29.1).
Pemphigus vulgaris and pemphigus foliaceus are the originally characterized, classic forms of pemphigus. All patients with pemphigus vulgaris have mucosal membrane erosions, and more than half will also have cutaneous blisters and erosions. The blisters of pemphigus
Masayuki Amagai Pemphigus 29
vulgaris develop within the deeper portion of the epidermis, just above the basal cell layer. Patients with pemphigus foliaceus only have cutaneous involvement without mucosal lesions, and the splits occur in the superficial portion of the epidermis, mostly at the granular layer. Pemphigus vegetans is a variant of pemphigus vulgaris, and pemphigus erythematosus and fogo selvagem represent localized and endemic variants of pemphigus foliaceus, respectively.
Paraneoplastic pemphigus is distinct from the classic forms of pemphigus, as it consists of both humoral and cellular autoimmune reactions. Patients with paraneoplastic pemphigus have a known or occult associated neoplasm, usually of lymphoid tissue. Painful, severe oral and conjunctival erosions are a prominent feature of paraneoplastic pemphigus.
Table 29.1 Classification of pemphigus.