Pemphigus is a rare, devastating, bullous autoimmune disease that damages the skin and mucous membranes, and has high morbidity and mortality. Studies have shown associations of pemphigus vulgaris (PV) and pemphigus foliaceus (PF) with human leukocyte antigen (HLA) class II polymorphisms.This study examined the frequency of Major Histocompatibility Complex, Class II, DR Beta 1, a Protein Coding gene (HLA-DRB1) and Major Histocompatibility Complex, Class II, DQ Beta 1 (HLA-DQB1) alleles in Vietnamese PV and PF patients, and the association of these polymorphisms with pemphigus subtypes and disease severity.The study enrolled 31 unrelated Vietnamese who underwent HLA typing using Sanger sequencing. HLA-DRB1 * 14:54 was the most frequent allele in both PV (20.5%) and PF (33.3%) patients. The percentage of HLA-DQB1 * 03:02 was significantly higher in PF than PV patients, while the percentage of HLA-DQB1 * 05:03 was approximately 10 times higher in PV patients. Pemphigus patients who have the HLA-DRB1 * 04 alleles are more likely to have mild or moderate disease.The HLA-DRB1 and DQB1 alleles may influence susceptibility to pemphigus subtypes, with DQB1 * 05:03 being specific for PV and DQB1 * 03:02 for PF. Our findings suggest that the DRB1 * 04 alleles are likely to be associated with mild and moderate disease.Abbreviations: HLA = human leukocyte antigen, PDAI = pemphigus disease area index, PF = pemphigus foliaceus, PV = pemphigus vulgaris.

Methotrexate (MTX) has been approved for the treatment of psoriasis and is considered to be effective and relatively safe. This drug was widely used for treatment of psoriasis in Vietnam for many years. Life-threatening MTX toxicity is rare but may rapidly develop when the drug is administered. In line with the interface dermatitis and a remarked eosinophilic infiltration in the cutaneous lesion, the diagnosis of hypereosinophilia as an adverse reaction in our patient was supported by the dramatic improvement of symptoms and decreased eosinophils after withdrawal of MTX. To the best of our knowledge, this is the first case that showed isolated hypereosinophilia as an adverse reaction of MTX in psoriasis treatment that may challenge in early recognition. Awareness and prompt recognition of this severe adverse reaction can result in life-saving discontinuation of MTX.