Pemphigus refers to a group of autoantibody-mediated intraepidermal blistering diseases characterized by loss of cohesion between epidermal cells (a process termed acantholysis).
Manual pressure to the skin of these patients may elicit the separation of the epidermis (Nikolsky’s sign).
Associated diseases PV has been associated with many other autoimmune diseases, particularly thyroid disease and rheumatoid arthritis ,type 1 diabetes
Pemphigus target antigens and the desmoglein compensation hypothesis The principal target antigens in pemphigus are desmogleins (Dsg) 1 and 3, which are expressed in the skin and mucosal tissue.
However, the distribution of the two proteins varies in different epithelia, such that in skin there is a high level expression of Dsg 1 throughout the epidermis whereas Dsg 3 is found only in the basal and immediate suprabasal layers.
The predominant class of tissue‐bound pemphigus antibody in pemphigus is immunoglobulin G (IgG), antibodies against desmocollins, plakoglobin, E‐cadherin .
The key pathological process in PV is separation of keratinocytes from one another, a change known as acantholysis.It is due to the presence of anti-Dsg antibodies.
Pesticides have also been postulated as possible triggers in disease development and an increased risk of pemphigus has been shown in exposed individuals Organophosphate pesticides block the acetylcholine breakdown pathway and so may lead to acetylcholine accumulation with resulting loss of cell–cell adhesion in the epidermis.
Drug‐induced pemphigus Most cases have been in association with drugs containing a thiol group such as penicillamine although non‐thiol drugs including angiotensin‐converting enzyme inhibitors and glibenclamide, cephalosporins, rifampicin, pyritinol, phenobarbital and aspirin
Exposure to crystalline silica e.g., inhalation of soap powder dust
Soil in farming activities due use of pesticides, artificial fertilizer
Autoimmunity-inducing activation of innate immunity
T and B cell hyperactivity(adaptive immunity)
Persistence of immune complexes
Environmental and gene interaction
This disease is characterized by fragile, flaccid blisters that rupture to produce extensive denudation of mucous membranes and skin .The mouth, scalp, face, neck, axilla, groin, and trunk are typically involved. PV may be associated with severe skin pain ,some patients experience pruritus
Flaccid blisters may occur in conjunctiva, nasopharynx, larynx, oesophagus urethra, vulva and cervix. Healing occurs without scarring but pigmentary change may occur in resolving lesions
Nail dystrophies, acute paronychia and subungual haematomas have been observed
IgG antibodies to Dsg 3, Dsg1