Mima Yoshihito, Ohtsuka Tsutomu
Department of Dermatology, Tokyo Metropolitan Police Hospital, Tokyo, JPN.
Department of Dermatology, International University of Health and Welfare Hospital, Tochigi, JPN.
Cureus. 2025 Feb 15;17(2):e79070. doi: 10.7759/cureus.79070. eCollection 2025 Feb.
Prurigo nodularis (PN) is a chronic inflammatory skin disorder characterized by intensely pruritic nodules. The pathogenesis of PN involves immune dysregulation, with a predominance of T helper (Th2)-type inflammation, including interleukin (IL)-4, IL-5, IL-13, and IL-31. Nemolizumab, an IL-31 receptor A inhibitor, was newly approved for PN in 2024. We report a case of erythema multiforme (EM) that developed three weeks after the first administration of nemolizumab. Three weeks post-injection, she developed multiple targetoid edematous erythematous patches and plaques on her trunk and limbs, leading to a clinical diagnosis of EM. Since she had no new medications and no recent history of infections, we inferred that the development of EM was likely associated with the administration of nemolizumab. The pathophysiology of EM involves a predominant Th1-driven inflammatory response. Therefore, nemolizumab likely suppressed Th2 inflammation, leading to compensatory Th1 hyperactivation, which may have triggered EM. To our knowledge, this may be the first reported case of EM following nemolizumab treatment for PN. Further research is necessary to investigate its immunomodulatory effects and potential adverse events.
结节性痒疹（PN）是一种慢性炎症性皮肤病，其特征为剧烈瘙痒的结节。PN的发病机制涉及免疫失调，以辅助性T（Th2）型炎症为主，包括白细胞介素（IL）-4、IL-5、IL-13和IL-31。奈莫利珠单抗是一种IL-31受体A抑制剂，于2024年新获批用于PN的治疗。我们报告了1例在首次使用奈莫利珠单抗3周后发生多形红斑（EM）的病例。注射后3周，她的躯干和四肢出现多处靶形水肿性红斑斑块，临床诊断为EM。由于她没有使用新的药物，近期也没有感染史，我们推断EM的发生可能与奈莫利珠单抗的使用有关。EM的病理生理学涉及以Th1为主导的炎症反应。因此，奈莫利珠单抗可能抑制了Th2炎症，导致代偿性Th1过度激活，这可能引发了EM。据我们所知，这可能是首例奈莫利珠单抗治疗PN后发生EM的报道病例。有必要进一步研究以调查其免疫调节作用和潜在不良事件。
