Bullous pemphigoid (BP) is a chronic autoimmune subepidermal blistering disease most frequently seen in the elderly. IgG autoantibodies bind to antigens that comprise the hemidesmosome adhesion complex in the basement membrane of the skin (BP180 or BP230). This triggers complement activation and release of inflammatory mediators, resulting in the formation of local or generalized tense bullae. The disease can occur on any body surface, but mucous membrane involvement is rare.
Relapse of BP has been shown to be more likely in individuals with extensive involvement and dementia. BP has been associated with other neurologic disorders. BP has also been associated with other autoimmune diseases such as diabetes mellitus, thyroiditis, dermatomyositis, lupus erythematosus, rheumatoid arthritis, ulcerative colitis, myasthenia gravis, and multiple sclerosis in case reports and case series. A population-based study from Finland strongly suggests an increased risk of BP in patients with dermatitis herpetiformis. Therapeutic radiation or drugs (furosemide, NSAIDs, captopril, penicillamine, gliptins, and some antibiotics) have also been associated with BP. It may also follow certain nonbullous inflammatory skin diseases, such as psoriasis and lichen planus, or vaccination (most often in children).
In patients of Northern European descent, there has been a significant association with the DQB1*0301 allele, whereas patients of Japanese descent have a higher frequency of alleles DRB1*04, DRB1*1101, and DQB1*0302.
The condition is often self-limiting, but it can become chronic over months to years. There is a wide spectrum of clinical severity. The disease can be generalized and severe, or patients may have only a few asymptomatic, localized bullae. There is no ethnic or sex predilection.
In some instances, early BP lesions will appear as pruritic urticarial papules and plaques (known as urticarial BP). The urticarial prebullous phase may vary in length from weeks to many months. Prebullous BP may present with pruritus only or itchy papules or nodules without urticarial plaques. This variant is known as nonbullous BP.
Peripheral eosinophilia is common and is positively correlated with disease severity. Its presence has also been correlated with older age and palmoplantar involvement. Lack of peripheral eosinophilia has been positively correlated with younger age and mucosal disease.
L12.0 – Bullous pemphigoid
77090002 – Bullous pemphigoid
- Diabetic bullae, which often erode and are large in size, may be confused with BP, but they are commonly solitary.
- Stasis dermatitis with bullae
- Insect bite reaction
- Bullae secondary to lymphedema
- Bedbug bite
- Flea bite
- Contact dermatitis with bullae
- Poison ivy dermatitis
- Bullous impetigo will have associated honey-colored crust.
- Bullous cellulitis
- Epidermolysis bullosa acquisita can be difficult to distinguish but may have the additional findings of milia; biopsy with direct immunofluorescence is helpful.
- Mucous membrane pemphigoid is a scarring, blistering disease that involves the mucosal surfaces.
- Pemphigoid gestationis is a variant of BP that presents in pregnant or postpartum females.
- Linear IgA dermatosis often presents with a cluster of vesicles on an erythematous base.
- Dermatitis herpetiformis rarely has intact bullae secondary to excoriation.
- Porphyria cutanea tarda or pseudoporphyria presents with bullae, milia, and hypertrichosis in sun-exposed areas.
- Pemphigus vulgaris or foliaceus have flaccid (fragile) bullae.
- Prurigo nodularis
- Dyshidrotic eczema