Bullous Pemphigoid - A Blistering Skin Disease

Introduction: Bullous pemphigoid is an autoimmune condition causing sub epidermal blistering of the skin. If untreated, it can persist for months or years, with periods of spontaneous remissions and exacerbation. The disease can be fatal, particularly in patients who are debilitated.
Bullous pemphigoid is most common in people older than age 60.

Pathophysiology: The bullae are formed by an immune reaction, initiated by the formation of IgG autoantibodies targeting Dystonin, also called Bullous Pemphigoid Antigen. It can also occur secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230.

Clinical features: The primary feature of bullous pemphigoid is the appearance of large blisters that don't easily rupture when touched. The fluid inside the blisters is usually clear but may contain some blood. The skin around the blisters may appear normal, reddish or darker than usual. Some people with bullous pemphigoid develop an eczema or hive-like rash rather than blisters.

In most cases, the blisters appear on the lower abdomen, groin, upper thighs and arms. Blisters are often located along creases or folds in the skin, such as the skin on the inner side of a joint.

The affected areas of skin can be very itchy.

If the mucous membranes of the eyes and mouth are primarily where the blisters are concentrated, this type of condition is called mucous membrane pemphigoid.

This condition requires prompt diagnosis and treatment.

Several distinct clinical presentations, has been desecribed as follows:
Generalized bullous form: The most common presentation; tense bullae arise on any part of the skin surface, with a predilection for the flexural areas of the skin
Vesicular form: Less common than the generalized bullous type; manifests as groups of small, tense blisters, often on an urticarial or erythematous base
Vegetative form: Very uncommon, with vegetating plaques in intertriginous areas of the skin, such as the axillae, neck, groin, and inframammary areas
Generalized erythroderma form: This rare presentation can resemble psoriasis, generalized atopic dermatitis, or other skin conditions characterized by an exfoliative erythroderma
Urticarial form: Some patients with bullous pemphigoid initially present with persistent urticarial lesions that subsequently convert to bullous eruptions; in some patients, urticarial lesions are the sole manifestations of the disease
Nodular form: This rare form, termed pemphigoid nodularis, has clinical features that resemble prurigo nodularis, with blisters arising on normal-appearing or nodular lesional skin
Acral form: In childhood-onset bullous pemphigoid associated with vaccination, the bullous lesions predominantly affect the palms, soles, and face
Infant form: In infants affected by bullous pemphigoid, the blisters tend to occur frequently on the palms, soles, and face, affecting the genital areas rarely; 60% of these infant patients have generalized blisters.

Diagnosis: is by skin biopsy in which immunofluorescence shows IgG and C3 at the dermoepidermal junction. 

Management:

• Referral to dermatologist for biopsy and confirmation of diagnosis
• Oral corticosteroids are the mainstay of treatment
• Topical corticosteroids, immunosuppressants and antibiotics are also used