Bullous Pemphigoid

Question 1

What is bullous pemphigoid (BP)?

Answer 1

A chronic autoimmune blistering disorder characterized by subepidermal blisters and autoantibodies targeting hemidesmosomal proteins in the basement membrane.

Question 1

Which proteins are targeted in bullous pemphigoid?

Answer 1

BP180 (collagen XVII) and BP230, components of hemidesmosomes.

Question 2

What is the hallmark feature of BP?

Answer 2

Tense, fluid-filled blisters on an erythematous or normal base.

Question 3

Who is most commonly affected by bullous pemphigoid?

Answer 3

Elderly individuals, typically over 60 years of age.

Question 4

What triggers bullous pemphigoid?

Answer 4

Autoantibodies against BP180 and BP230 disrupt dermoepidermal adhesion, leading to complement activation, inflammation, and blister formation.

Question 5

What cells mediate the inflammatory response in BP?

Answer 5

Eosinophils, neutrophils, and lymphocytes.

Question 6

What role does complement activation play in BP?

Answer 6

It enhances the recruitment of inflammatory cells that degrade the basement membrane, leading to blistering.

Question 7

What are the primary skin findings in BP?

Answer 7

Tense bullae on erythematous or normal skin.

Lesions are typically non-fragile and do not rupture easily.

Often associated with pruritus.

Question 8

What are common sites for BP lesions?

Answer 8

Flexural areas, lower abdomen, inner thighs, and arms, but it can be generalized.

Question 9

Can mucous membranes be involved in BP?

Answer 9

Rarely, but mild mucosal involvement can occur in some cases.

Question 10

What is the prodromal phase of BP?

Answer 10

An urticarial or eczematous phase with pruritus, which may precede blister formation.

Question 11

How is bullous pemphigoid diagnosed?

Answer 11

Clinical features: Tense bullae and pruritus.

Skin biopsy for histology: Subepidermal blister with eosinophilic infiltrate.

Direct immunofluorescence (DIF): Linear IgG and/or C3 deposition along the basement membrane zone.

Serology: Detection of circulating anti-BP180 and anti-BP230 antibodies by ELISA.

Question 12

What is the role of DIF in BP diagnosis?

Answer 12

It is the gold standard, confirming IgG/C3 deposition along the basement membrane zone.

Question 13

What conditions should be considered in the differential diagnosis of BP?

Answer 13

Pemphigus vulgaris (fragile intraepidermal blisters).

Dermatitis herpetiformis (smaller, grouped vesicles, intense pruritus).

Linear IgA dermatosis (subepidermal blisters with IgA deposition).

Erythema multiforme (target lesions with central blistering).

Question 14

What are the goals of treatment in BP?

Answer 14

Reduce inflammation, suppress autoantibody production, and prevent secondary infections.

Question 15

What are the first-line treatments for BP?

Answer 15

Topical corticosteroids: High-potency (e.g., clobetasol) for localized or moderate disease.

Systemic corticosteroids: Prednisone for extensive or severe disease.

Question 16

What immunosuppressive agents are used in refractory BP?

Answer 16

Azathioprine.

Methotrexate.

Mycophenolate mofetil.

Cyclophosphamide.

Question 17

What are biologic therapies for BP?

Answer 17

Rituximab (anti-CD20 monoclonal antibody) is used for severe or refractory cases.

Question 18

How are mild cases of BP managed?

Answer 18

With topical corticosteroids and oral tetracyclines (e.g., doxycycline) combined with nicotinamide.

Question 19

What factors are associated with a poor prognosis in BP?

Answer 19

Advanced age, poor general health, and widespread disease.

Question 20

What medications are associated with drug-induced BP?

Answer 20

Loop diuretics (e.g., furosemide).

Penicillins.

ACE inhibitors.

Dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g., sitagliptin).

Question 21

What other factors can trigger BP?

Answer 21

Physical trauma, UV radiation, and infections.