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Genome-wide association studies have identified more than 60 susceptibility loci for psoriasis, highlighting the role of genetics in psoriasis development. Although the HLA region is suggested as the most prominent susceptibility locus, the role of the HLA haplotype in the development of psoriasis is unclear. The aim of this study is to investigate how HLA haplotype changes affect the onset of psoriasis and which HLA haplotypes are associated with the development of psoriasis. A longitudinal, retrospective case series study of children was conducted at Tohoku University Hospital in Japan, between November 1981 and October 2020. We evaluated a total of 378 pediatric patients who underwent hematopoietic stem cell transplantation in the Department of Pediatrics. The background of these patients and their HLA haplotypes before and after transplantation was assessed. Among the 378 cases, aged 0-22 years old (median age 6) identified, 117 cases received autologous transplantation, 260 cases received allogeneic transplantation, and one case received syngeneic transplantation. Only two cases developed de novo psoriasis, and these cases had acquired HLA-B46-Cw1 after allogeneic transplantation. Others who had HLA-B46-Cw1 before and after allogeneic transplantation did not develop psoriasis. Our findings suggest that the HLA-B46 and HLA-Cw1 combination contributes to the development of psoriasis in this Asian population., (© 2021 Japanese Dermatological Association.)

A case of atopic dermatitis (AD) with X-linked agammaglobulinemia (XLA), which is one of the primary immunodeficiency diseases, is reported. A 12-year-old boy had suffered from dry skin and recurrent itchy eruptions since he was 2 years old, and he was diagnosed as having XLA at the age of 4 years. His total immunoglobulin (Ig)E level was 7 IU/mL, even with regular Ig replacement therapy. Furthermore, filaggrin (FLG) mutations known in the Japanese population were not found. His skin lesions were well controlled by the application of a mild-class topical steroid and a moisturizer, though he developed folliculitis due to Staphylococcus aureus infection during treatment with a strong-class topical steroid. This case suggests that the FLG mutation and IgE-mediated sensitization are not necessary to induce AD skin manifestation., (© 2019 Japanese Dermatological Association.)

We report a 9-year-old Japanese female patient with atopic dermatitis associated with idiopathic thrombocytopenic purpura. She demonstrated high serum immunoglobulin (Ig)E and IgE specific to several environmental allergens, but extremely low serum thymus and activation-regulated chemokine (TARC) levels regardless of the disease progression. This case suggests platelets as the main source of serum TARC., (© 2018 Japanese Dermatological Association.)

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder that is caused by inactivating mutations or a loss of both alleles in the NF2 tumor-suppressor gene. Bilateral vestibular schwannomas are considered to be the hallmark of this disease, with hearing loss and tinnitus which are caused by these tumors, usually presenting as the initial symptoms. In addition to other tumors and ocular findings, skin abnormalities also occur in NF2, however, they are not so characteristic as neurofibromatosis type 1 (NF1). We herein report a case of NF2 which occurred in a 5-year-old boy. He had multiple cutaneous tumors but did not have any symptoms related to vestibular schwannomas. He also had multiple depigmented spots. A histopathological examination revealed these tumors to be plexiform schwannomas; we therefore suspected NF2. As a result of magnetic resonance imaging with gadolinium enhancement, bilateral vestibular schwannomas were detected and a final diagnosis of NF2 was thus made. The association between NF2 and multiple depigmented spots is unknown, we therefore consider that multiple cutaneous plexiform schwannomas may strongly suggest an association with NF2.