Pemphigus is a group of autoimmune blistering diseases characterized by blisters and erosive lesions on the skin and mucous membranes due to loss of cell and cell adhesion of keratinocytes. In 2010, new Japanese guidelines for the management of pemphigus were published for dermatologists. Systemic corticosteroid are the gold standard and the first choice of treatment of pemphigus. Desmoglein 1 (Dsg1) and desmoglein 3 (Dsg3) are the target antigens in pemphigus.

According to a report from a research project of the Ministry of Health, Labour and Welfare of Japan, the incidence of pemphigus in Japan was 4085 in 2007. The male-to-female ratio was 1:1.5. The average age of onset of the disease was approximately 60 years with a peak in the 50s. Among different subtypes in pemphigus; pemphigus vulgaris was 65%, pemphigus foliaceus 23%, pemphigus erythematosus 6%, pemphigus vegetans 2%, and the unclassified subtype 4%. Among the total Japanese cases, 5.0% were in the severe group, 20.4% in the moderate group, and 74.0% in the mild group, as evaluated by the Japanese disease severity score. In contrast, when focusing on new cases per year, 20.6% were in the severe group, 45.2% in the moderate group, and 34.2% in the mild group.

In 2010, new Japanese guidelines for the management of pemphigus were published for dermatologists and their English version will be published soon. In Japan, the gold standard and the first choice of treatment of pemphigus, as accepted worldwide, are systemic corticosteroids. The treatment protocol has two major phases: consolidation and maintenance. The consolidation phase indicates the initial phase of the treatment to control the disease activity (to minimize new blister formation and start to withdraw prednisolone [PSL] dosages, usually 2 to 4 weeks after the initial treatment); the maintenance phase is defined as the period when the disease is under control and the PSL is being reduced (early phase, PSL 60 to 20 mg/day; and late phase, PSL <20 mg/day). The definition and treatment goals follow the statement of the International Pemphigus Committee in 2008, namely to reduce the disease activity rapidly by using different therapeutic options and to control disease activity with minimal corticosteroid dosing (PSL ≤0.2 mg/kg/day or PSL ≤10 mg/day). The choice of adjuvant therapy in Japan is strongly influenced by the insurance system. High-dose intravenous immunoglobulin (IVIG) is an effective therapeutic option for refractory pemphigus. In Japan, a randomized double-blind controlled trial for high-dose IVIG for pemphigus was performed and demonstrated that a single cycle with high-dose IVIG successfully suppresses the disease activity of steroid-resistant pemphigus. Based on this study, IVIG has been covered by national insurance in Japan since 2009. Corticosteroid pulse therapy and plasmapheresis are other options used during the consolidation phase. As adjuvant therapies, immunosuppressants, such as azathioprine, cyclosporine, cyclophosphamide, and methotrexate, are considered steroid-sparing agents.

The guidelines also recommend the pemphigus disease area index (PDAI) as a new measure to evaluate pemphigus disease activity. In Japan, ELISA has been widely used not only for making serologic diagnosis but also for monitoring disease activity. The cost for ELISA is covered by national insurance. In the consolidation phase, when active lesions still exist, the disease activity is evaluated by PDAI, whereas in the maintenance phase, when no active lesions are seen, ELISA provides a useful indicator for guidance in reducing corticosteroids. By using a combination of the PDAI and ELISA, pemphigus can be managed in a more objective and efficient way.

Although rituximab and mycophenolate mofetil are widely recognized as efficient drugs for refractory cases of pemphigus, they are not yet approved in Japan. Government approval requires independent clinical trials to be conducted in Japan. On the other hand, Japan has a unique system to cover essentially all the medical costs, including inpatient care, for patients with 56 intractable diseases. Pemphigus is approved as one of the intractable diseases.