Department of Dermatology
Keio University School of Medicine

 Amagai has further developed the tradition of “strength in clinical practice and depth in research” built up by his predecessors. He runs the department with the motto “創知育成” coined by him, meaning “create new knowledge and nurture people,” with an emphasis on diversity and communication.
 In 1991, while working as a postdoctoral fellow at the laboratory of Dr. John R. Stanley, the National Institute of Health in the USA, he succeeded in the isolation of the cDNA for pemphigus vulgaris antigen and revealed it to be desmoglein 3 (Dsg3). In 2000, he discovered that the S. aureus exfoliative toxin that induces staphylococcal scalded skin syndrome (SSSS) and bullous impetigo is an enzyme that cleaves desmoglein 1. He also generated a pemphigus model in mice through a unique method using autoantigen knockout mice. Since 2013, he has also served as a team leader at the RIKEN Center for Integrative Medical Sciences and is active in broadening the scope of essential areas of basic research. In 2016, he was elected as an international member of the National Academy of Medicine in USA. Since October 2017, he has been appointed as Dean of Keio University School of Medicine. He became President of the Japanese Dermatological Association in 2018 and served as the president of the 119th Annual Meeting of the Japanese Dermatological Association, which was held virtually because of the COVID-19 pandemic in 2020.

Clinical practice: Working with a policy of taking care of all skin-related diseases, medical treatment in the department is conducted with a system for handling a wide range of skin diseases. In the outpatient department, in the morning, we provide medical services for initial visit patients as well as follow up patients. In the afternoon we provide a wide range of specialized outpatient services, including autoimmune blistering diseases, atopic dermatitis, psoriasis, hereditary diseases, allergies and drug reactions, skin tumors and malignancies, hair loss, nail deformity, laser treatment, and cutaneous collagen diseases. With regard to unusual and difficult cases, we perform clinical conferences with patients’ views, histology presentation of biopsied samples and group discussion among the department staffs to decide on the diagnosis and treatment plan. We perform genetic analysis such as whole-exome sequencing for rare inherited diseases and undiagnosed cases. On the ward, we cooperate with the other departments and medical sections to manage severe diseases such as pemphigus, pemphigoid, and skin malignancies including melanoma. The main wards have moved from the second floor of Hospital Wing 6 and ward 6S of Building No. 2 to the tenth floor of Building No. 1 with approximately 16–20 beds. We perform 60–70 general anesthetic operations a year. The clinical research described below is the driving force of our clinical practice, and we treat patients from across the country.

Research: Our research activities are constantly being developed to achieve high-impact research results on an international level in both foundational and clinical aspects. In research on the elucidation of pemphigus pathophysiology that has been ongoing since the time of Nishikawa, achievements include isolation of pemphigus monoclonal antibody with pathogenicity from pemphigus model mice (Kazuyuki Tsunoda et al.), isolation of Dsg3-specific T-cell clones and the pathophysiology of interface dermatitis by cellular immunity against epidermal autoantigens (Hayato Takahashi et al.), and research is ongoing toward the development of antigen-specific immunosuppressive therapies. In studies on skin barrier function, there have been many research findings, including a discovery of behavior of epidermal Langerhans cells extending dendrites above tight junctions to capture foreign antigens (Akiharu Kubo et al.), a discovery of hair follicle immune function whereby hair follicles produce chemokine as immunosensor to external stimulation (Keisuke Nagao et al.), the induction of differentiation into human hair follicles using iPS cells (Manabu Ohyama et al.); the identification of the causative gene for Nagashima-type palmoplantar keratosis; and the implication that terminal-differentiated epidermal cells (SG1 cells in stratum granulosum) naturally take the form of a Kelvin tetrakaidecahedron.
 Since Keio University Hospital was certified as a clinical research core hospital in 2016, a range of findings in clinical research have also been developed, including efficacy verification of rituximab (anti-CD20 monoclonal antibody) for refractory pemphigus through multicenter joint doctor-led clinical trials (Jun Yamagami et al.); evaluation of the efficacy of TIL treatment for malignant melanoma as a clinical trial (Takeru Funakoshi et al.); analysis of skin microbiota involved in atopic dermatitis, and analysis using medical information big data such as immunological, pathological, and genetic information (Tamotsu Ebihara, Hiroshi Kawasaki et al.); verification of the effects of hydroxychloroquine on skin and systemic lupus erythematosus (Akiko Tanikawa et al.); and new development of a corrective treatment for ingrown toenails (Masataka Saito et al.).

Education: Education is the most important part of running the department and nurturing the people we work with. Many department staff members have grown from the basis of traditions that have been passed down from generation to the next. We value diversity, take in a range of talented individuals from all over the country, and make every effort to make every individual in the department into an excellent dermatologist. For undergraduate students, in addition to classroom lectures, we conduct clinical clerkship for two weeks for grade 5 and 6 students. In the outpatient clinic, students examine the medical history of patients and evaluate skin lesions on their first visit and think of possible diagnosis and treatment plans with guidance from staff doctors. In the ward, students work with the ward physician and make reports on assigned cases. Within the two-week rotation, short lectures are given daily by the dermatology staff, and students learn a wide range of fields of fundamental, clinical, and research dermatology. Junior residents select to rotate dermatology for 1–3 months during their two-year training. In the outpatient department, junior residents or super-rotators will gain an understanding of the process from diagnosis to treatment of various skin diseases, learning skin biopsy procedures, and further giving presentations at clinical conferences. In the ward, residents belong to a team and cultivate an understanding of the dermatological perspective through investigation of the causes and treatments of cases they are in charge of.
 If senior residents choose dermatology in their specialized training, which takes five years to complete, they belong to the department and work as members of the team. Since the clinical training system for junior residents was introduced in 2004, 7–8 specialist physicians have joined the department annually. After basic dermatology training at a university that includes over 50 short lectures, more practical training is provided at over 20 affiliated hospitals located in Tokyo, Kanagawa, Chiba, Saitama, and Shizuoka Prefectures. After 2–3 years of this practical training, senior residents return to the university to undergo more specialized and advanced training. We have an integrated education system with affiliated hospitals and universities that is unique to Keio University.
 We are also active in international exchange programs, taking on large numbers of international students and residents, as well as junior and senior faculties from the USA, Europe, and Asia. Since 1998, we have been conducting an exchange program with the University of Pennsylvania based on a proposal by Dr. John R. Stanley, in which staff members and residents have a short stay of about two weeks, and in 2017, over 25 people had benefited from the exchange.