What is the main difference between pemphigus and pemphigoid regarding the nature of the blisters?

Pemphigus and pemphigoid are autoimmune skin diseases that cause blisters on the skin and mucous membranes. The primary difference between them lies in the nature of the blisters and the specific layer of the skin where they form. In pemphigus, the blisters are superficial and fragile, whereas in pemphigoid, the blisters are deep and more robust.

Both conditions occur when the body's immune system mistakenly attacks its own healthy cells [2]. In pemphigus, the immune system attacks proteins called desmogleins, which bind the cells of the top layer of the skin (the epidermis) together. When these connections are broken, the skin becomes fragile and fluid collects between its layers, leading to blister formation [1]. In pemphigoid, the immune system targets the proteins that connect the top layer of the skin to the lower layer, leading to the separation of these two layers and the formation of deep blisters [3].

Nature and Location of Blisters

• Pemphigus: Blisters in pemphigus are characterized by being fragile and easily ruptured, leaving behind crusted sores. These blisters can appear on the skin as well as inside the mouth, nose, throat, eyes, and genitals [1]. In the case of Pemphigus vulgaris, blisters often start inside the mouth and may then spread to the skin. These blisters are painful and form in a deep layer of the epidermis. In Pemphigus foliaceus, blisters appear on the upper layers of the epidermis and affect only the skin; they are often itchy or painful [1].
• Pemphigoid: Unlike pemphigus, blisters in pemphigoid are deep and firm, and they do not rupture easily [2]. These blisters are often accompanied by intense itching and typically appear on the arms, legs, or midsection [3]. In rare cases, blisters can form inside the mouth [3].

Age Groups Most Affected

The age at which these two diseases typically appear differs:

• Pemphigus: Pemphigus vulgaris often appears between the ages of 50 and 60 [1]. There may be a genetic predisposition to pemphigus in certain populations, such as those of Jewish (specifically Ashkenazi), Indian, Southeast European, or Middle Eastern descent [1].
• Pemphigoid: Pemphigoid usually affects older adults and is rare in young people [3].

Diagnosis and Treatment

To diagnose both pemphigus and pemphigoid, doctors perform a physical examination, a skin biopsy, and blood tests [2]. These tests can help identify the type of antibodies present and the location of blister formation.

The primary treatment for both diseases aims to control symptoms and reduce immune system activity. Treatment usually includes [2]:

• Corticosteroids: To reduce inflammation, which may be taken orally or applied to the skin [3].
• Immunosuppressants: Used if steroids alone are not effective, or to allow for a reduction in steroid dosage [3].
• Antibiotics: To treat any associated skin infections [2].

Next Steps and Warning Signs

Because both diseases are chronic autoimmune conditions, regular follow-up with a dermatologist is essential. There is no cure for pemphigus, but it can be managed with medication in many cases [1]. Pemphigoid often responds well to treatment, and it may be possible to discontinue medications after several years, although the disease can sometimes recur after treatment is stopped [3].

If you notice unexplained blisters on your skin or an itchy rash that persists despite home treatments, you should contact your healthcare provider [3]. Complications such as skin infections can be common, especially if blisters rupture and form open sores [3]. For more information on these diseases, you can visit Pemphigus and Pemphigoid: Differences, Diagnosis, and Immunological Treatment (Arabic).

Medical references

• Pemphigus
• Pemphigus
• Bullous pemphigoid