Bullous pemphigoid (BP) is the most common autoimmune sub-epidermal blistering disorder in adults. It generally affects older individuals, commonly those between 60 and 80 years of age. In BP, the body produces autoantibodies directed against structural proteins at the dermal-epidermal junction, especially the hemidesmosomal antigens often referred to as BP180 and BP230. As a result, adherence between the epidermis and dermis is disrupted, leading to subepidermal blister formation. Because of its autoimmune nature and the target antigens at the basement membrane zone, BP belongs to the group of immunobullous skin diseases.
Why Does Bullous Pemphigoid Occur?
The underlying mechanism of BP involves the production of autoantibodies against hemidesmosomal proteins that normally anchor the epidermis to the dermis. When these autoantibodies bind to their target antigens (BP180 and BP230), they activate complement and recruit inflammatory cells such as neutrophils, eosinophils, and mast cells to the dermal-epidermal junction. The enzymes and reactive oxygen species released by these inflammatory cells degrade adhesion structures, causing separation at the DEJ and resulting in blister formation. In many patients, triggering factors remain unclear; in some cases, medications or other environmental factors may precipitate disease onset.
Thus, BP is fundamentally an autoimmune disease characterized by antibody-mediated injury and inflammation at the skins basement membrane zone.
What Are the Typical Clinical Features of Bullous Pemphigoid?
The typical presentation of BP is the emergence of tense blisters filled with clear—or sometimes hemorrhagic—fluid, on normal or inflamed skin. These blisters often develop on the trunk, abdomen, or flexural surfaces of limbs, though any skin area may be involved. The bullae are typically tense, meaning they are firm and less fragile than the flaccid blisters seen in other blistering diseases such as pemphigus vulgaris.
However, BP does not always present with blisters. In about 20% of cases, the disease begins with or remains limited to non-bullous forms: intense itching, urticarial or eczematous patches, papules, or excoriations. This non-bullous phase may last for weeks to months before bullae develop, or may persist without blister formation.
Patients often experience severe pruritus, sometimes for a prolonged period before evident blistering arises. Mucosal involvement (e.g., inside the mouth) is less common compared to some other blistering diseases.
Because of its variable presentation—ranging from simple itching and urticarial rash to widespread blistering—BP can be difficult to identify, and misdiagnosis or delays in diagnosis are common.
Can Dermoscopy Aid in the Diagnosis of Bullous Pemphigoid?
Dermoscopy is primarily used in the evaluation of pigmented and non-pigmented skin tumors, but it serves as a non-invasive, supplementary tool in the diagnostic process for inflammatory bullous diseases like BP. While dermoscopic features alone are insufficient for a definitive diagnosis, they can support clinical suspicion and guide the location of diagnostic biopsies.
Dermatoscopy may show several supportive but non-specific features:
(1) In early or non-bullous BP:
• Fine linear or dotted vessels
• A pink or reddish inflammatory background
• Patchy or reticular vascular patterns
(2) In established blisters:
• A smooth, translucent blister roof
• A pale-to-yellow fluid cavity
• Peripheral erythema or vascular dilation
(3) In healing or resolved lesions:
• Brown or gray-brown pigmentation
• Post-inflammatory pigmentary changes
The visualization of these intense inflammatory and vascular patterns can assist in differentiating BP from other conditions, such as simple dermatitis or scabies, by highlighting the underlying inflammatory vasculopathy, but confirmation always requires immunofluorescence and histopathology.
How Is Bullous Pemphigoid Treated?
The aims of treatment are to suppress blister formation, reduce inflammation and itching, promote healing of existing lesions, and prevent new lesions, while managing side effects.
In many cases, high-potency topical corticosteroids are recommended—especially for limited or localized disease—to reduce systemic side effects. For more widespread, severe, or rapidly progressing disease, systemic corticosteroids such as oral prednisone may be used; typical regimens begin at moderate doses and then taper as control is achieved. Because long-term use of systemic steroids carries risk—particularly in the elderly—clinicians often combine steroid-sparing treatments.
In recent years, biological therapies and targeted immunomodulators have emerged as promising treatments, aiming to reduce antibody production or blunt inflammatory pathways, which may offer safer long-term management alternatives. And because the skin barrier is disrupted, patients are vulnerable to secondary infections (bacterial or viral), and gentle skin care and hygiene are critical.
Is Bullous Pemphigoid Life-Threatening or Chronic?
Bullous pemphigoid is generally a chronic disease. The course can vary: in some patients, effective therapy leads to remission within months; in others, disease may persist for years, with periods of relapse and remission.
Complications can occur, especially in older patients or those with comorbidities. These include secondary skin infections (bacterial or viral), sepsis, drug-related adverse effects, and increased morbidity due to frailty or immune suppression. Mortality rates remain higher in BP compared with the general population, due to age, comorbid conditions, and treatment complications.
Therefore, long-term monitoring, individualized therapy, and careful balancing of benefits vs. risks are essential.