Pemphigus vulgaris is a rare disorder that occurs most commonly in older adults and more often in women than in men. Lesions are painful, particularly when ruptured, and frequently develop secondary infections. Most affected patients have oropharyngeal involvement at some point in their course. The mainstay of treatment is immunosuppressive therapy, sometimes for life. Medications can induce pemphigus, more often pemphigus foliaceus than pemphigus vulgaris. There is also an unusual endemic form of pemphigus foliaceus in South America (fogo selvagem) that is putatively associated with the bite of a black fly.
Bullous pemphigoid is another distinctive acquired blistering disorder with an autoimmune basis.
Blistering in bullous pemphigoid is triggered by the linear deposition of autoreactive IgG antibodies and complement in the epidermal basement membrane (
Fig.
24.12A ). Reactivity also occurs in the basement membrane attachment plaques (hemidesmosomes), where most bullous pemphigoid antigen (most commonly type XVII collagen) is located. The proteins that are recognized by the autoantibodies have structural roles in dermoepidermal adhesion. IgG autoantibodies to hemidesmosome components fix complement and cause tissue injury by recruiting neutrophils and eosinophils. Bullous pemphigoid and pemphigus vulgaris are thus caused by similar pathogenic http://ebooksmedicine.net
Fig. 24.8 Levelsofblisterformation.(A)Subcorneal(asinpemphigusfoliaceus).(B)Suprabasal(asinpemphigusvulgaris).(C)Subepidermal(asinbullouspemphigoidordermatitisherpetiformis).
mechanisms, but differ in their clinical presentation and course due to variation in the location of the target antigen (hemidesmosomes in bullous pemphigoid, desmosomes in pemphigus).
Fig.24.12B ).Theoverlyingepidermischaracteristicallylacksacantholysis.Earlylesionsshowvariablenumbersofeosinophilsatthedermal-epidermaljunction,occasionalneutrophils,superficialdermaledema,andassociatedbasalcelllayervacuolization.Thevacuolatedbasalcelllayereventuallygivesrisetoafluid-filledblister(
Fig.24.12C ).Theblisterroofconsistsoffull-thicknessepidermiswithintactintercellularjunctions,akeydistinctionfromtheblistersseeninpemphigus.
Fig. 24.9 Directimmunofluorescencefindingsinpemphigus.(A)Pemphigusvulgaris.Notetheuniformdepositionofimmunoglobulin(green) alongkeratinocytecellmembranesinacharacteristic“fishnet”pattern.(B)Pemphigusfoliaceus.Immunoglobulindepositsareconfinedtosuperficiallayersoftheepidermis.
The lesions of bullous pemphigoid do not rupture as readily as in pemphigus and, if uncomplicated by infection, heal without scarring. The disease tends to follow a remitting and relapsing course and responds to topical or systemic immunosuppressive agents. Gestational pemphigoid (also known as herpes gestationis, a misnomer since there is no viral etiology) is a clinically distinct subtype that appears suddenly during the second or third trimester of pregnancy. It also is caused by autoantibodies against bullous pemphigoid antigen. Gestational pemphigoid typically resolves after childbirth, but may recur with subsequent pregnancies.