Pemphigus vulgaris (PV) is a chronic autoimmune disease of cutaneous blisters with a high rate of death. Autoimmune pemphigus has three types: pemphigus vulgaris, pemphigus foliaceous, and paraneoplastic pemphigus.

Studies have shown that the age of disease onset, phenotype, severity, and also the rates of disease differ in different types of pemphigus diseases [1–3]. Pemphigus vulgaris is a severe autoimmune disease diagnosed by painful erosions and extensive blistering of the skin and mucous membranes. The clinical disease is the result of disruption in keratinocyte cell adhesion, called acantholysis, and is caused by autoantibodies against the desmosomal components [4, 5]. With a prevalence of 81.2%, pemphigus vulgaris is the most common blister autoimmune disease in Iran. It affects one to five people in one million, but it is higher in Ashkenazi Jews and eastern countries. In 2005, its prevalence in Iran was 30 in 100,000 people, and its incidence was 1 in 100,000 people per year [6, 7]. Pemphigus vulgaris affects both men and women to the same extent; however, its prevalence under age 20 is higher among women [8].

Race, sex, and onset age are important epidemiologic factors influencing the incidence of the disease [9, 10]. Some studies show that smoking has a protective role in the emergence of pemphigus vulgaris [11–13].

Some studies mentioned the age of disease onset is an important factor in disease advancement [14]. While a study by Savin et al. indicated that early treatment of pemphigus vulgaris results in higher risk of death [9], Herbst et al. showed that the initial response to the treatment has a crucial role in determination of remission [15]. The location of erosions and disease severity are also among the effective factors in remission. It was seen that the disease improvement was better in the patients whose erosions occurred on the skin [16, 17]. And the patients with mild to moderate severity (at the time of diagnosis) had two times more chance of long-lasting remission [15].

Pemphigus vulgaris can be diagnosed by four main criteria: (1) clinical findings, (2) optical microscopy, (3) direct immunofluorescence, and (4) indirect immunofluorescence [18]. Anti-epicutaneous autoantibodies are among the most important factors in pemphigus vulgaris, and among them desmoglein (DSG) 1 and 3 are of particular importance. It seems that anti-desmoglein antibodies cause acantholysis and activation of cell signaling.

There is no specific gold standard for assessment of disease severity in PV patients, and this could be due to the rarity of the disease.

It was observed that anti-DSG1 is accompanied with higher severity, and that in the patients with positive levels of anti-DSG1 and anti-DSG3, the disease is faster and more extensive [19]. In a study conducted by Harman et al., anti-DSG1 was positive in 75% of Indian and 46% of European patients with PV [19]. In the study of Barnadas et al., anti-DSG1 was positive in 36% of PV patients from Spain [7]. Differences in anti-DSG antibody distribution could be due to racial and phenotypic differences of disease.

Although anti-desmoglein 1 and 3 autoantibody levels are two factors capable of predicting disease activity, these tests are not usually used. Studying the amount of circulating antibodies with specific enzyme-linked immunosorbent assay (ELISA) kits is instead preferably used for diagnosis and tracking the autoimmune patients. Especially, in pemphigus vulgaris patients, tracking anti-desmoglein 1 or 3 of the serum is in accordance with the clinical type and severity of the disease. ELISA has high sensitivity and has made diagnosis of pemphigus subgroups possible, and its results can be used for determination of disease activity and controlling the response to treatment [20].

The Pemphigus Disease Area Index (PDAI) is an independent assessment method for disease activity that shows the extent of disease. PDAI is designed by the International Pemphigus Committee. PDAI has three components: one related to skin, one related to scalp, and one related to mucosal membranes.

The activity score is specific for the skin allocated to the number of erosions, blisters, or new erythema. Twelve anatomic points will be evaluated, and by summing these points, the final score will be obtained (Table 10.1) [21].