Episode Details

Episode 140: Bullous pemphigoid basics

Future Dr. Stetkevych explains the diagnosis and treatment of bullous pemphigoid. She explains how to differentiate BP from pemphigus vulgaris. Dr. Arreaza added some comments and summaries.  

Written by Katherine Stetkévych, MSIV, Ross University School of Medicine.

You are listening to Rio Bravo qWeek Podcast, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California, a UCLA-affiliated program sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. This podcast was created for educational purposes only. Visit your primary care provider for additional medical advice.

Definition. Bullous pemphigoid is an autoimmune condition in which the body produces antibodies against hemidesmosomes at the basement membrane of the skin. (Hemidesmosomes anchor the epidermis to the dermis.) As a result of this autoimmune reaction, inflammatory cells, and fluid fill under the epidermis, creating a blister.

As a reminder, a vesicle is a collection of free fluid <0.5 cm, and a bulla is the same but larger than 0.5 cm. Bullous pemphigoid is a member of the family of autoimmune subepidermal blistering diseases, which also includes herpes gestationis and cicatricial (sicatríshal) pemphigoid, but bullous pemphigoid is the most common out of that family and the one with the highest mortality. Let’s talk about the presentation.

Presentation.

Typically, bullous pemphigoid affects adults over the age of 60. We can say that it is a disease of elderly patients; the mean age of diagnosis is 80. There is no race or gender preference. The initial presentation is hives and pruritus. Patients may be itchy for ~10 months before the diagnosis. After patients have plaques, erythema, and itching, they have blisters. 

What is notable about the blisters in bullous pemphigoid is that the blisters are taut. They bulge out from the skin; however, they do not spread when pressure is applied laterally to the blister, and pressing on an unaffected skin area will not cause a new blister to form. The spread or creation of a blister with pressure is called the Nikolsky sign, and the fact that bullous pemphigoid is negative for the Nikolsky sign helps differentiate this condition from pemphigus vulgaris. Another notable feature is that the blisters of bullous pemphigoid are painless.

If the blisters rupture, patients may experience short-term pain, but the erosion on the skin after the blisters rupture heal fast without scarring. 

Bullous pemphigoid typically does not involve the oral mucosa; however, there is a subtype that does. Nonetheless, should a patient present with bullae that involve the oral mucosa, it is important to test for the Nikolsky skin, determine whether the blisters are painful, and work up the blisters to determine the correct diagnosis.

Diagnosis.
The differential diagnosis is extensive and includes dermatitis herpetiformis, bullous systemic lupus erythematous, bullous drug eruptions, bullous impetigo, even insect bites, burns, erythema multiforme, and contact dermatitis.

You can find non-specific findings such as peripheral eosinophilia in 50% of the patients. Serum tests include pemphigoid antibodies ELISA: BP 180 and 230 autoantibodies, desmoglein (desmoglain) 1 and 3. To get to a definitive diagnosis, you need a skin biopsy for histology and immunofluorescence. Histology will show subepidermal cleavage and the presence of inflammatory infiltrate with eosinophils or neutrophils. 

The diagnosis will be confirmed by direct immunofluorescence (DIF). The biopsy should be taken from inflamed skin next to a blister with 2/3 of normal skin and 1/3