Generalized pustular psoriasis (GPP) is a rare and intractable form of psoriasis and is considered an intractableand rare disease (known as nanbyo in Japanese) under the Act on Medical Care and Social Supports for Patientswith Intractable and Rare Diseases. GPP often develops in patients with plaque psoriasis, the most common formof psoriasis. The number of patients with a GPP designation is approximately 2000. Every year, approximately80 patients with moderate to severe GPP are newly eligible for subsidizing the expense of medical costs based ondesignation. Treatment for psoriasis, including GPP, has undergone major advances in the last 15 years. Recentepidemiological studies have shown that the quality of life of GPP patients has improved in parallel with the advance of treatment. In addition, through a survey of a claim database, we recently elucidated the risk factors forthe development of GPP in patients with psoriasis vulgaris. In this article, I discuss the results of recent epidemiological studies on GPP. Further research should contribute to the understanding of this rare disease, improvementof disease management, and improvement of patient QoL.
