Subcorneal pustular dermatosis masquerading as eczematous dermatitis: a case report and mechanistic review.

This case describes a woman with a decades-long history of misdiagnosed eczematous dermatitis ultimately identified as subcorneal pustular dermatosis (SPD), a rare neutrophilic dermatosis. Initially treated unsuccessfully for presumed atopic dermatitis and prurigo nodularis with various immunomodulatory agents, including dupilumab and Janus kinase (JAK) inhibitors, the correct diagnosis was made only after the appearance of characteristic flaccid pustules in intertriginous areas. Histopathological analysis confirmed SPD, and following intolerance to initial treatment with dapsone, the patient experienced a dramatic and sustained clinical improvement with infliximab. This case highlights the diagnostic challenges posed by atypical presentations of SPD and supports the use of tumour necrosis factor-alpha (TNFα) inhibitors as a highly effective treatment option.