Pustular Mycosis Fungoides Triggered by Systemic Interferon-γ

Area of Science:

• Dermatology
• Immunology

Background:

• Pustular mycosis fungoides (pMF) is a rare variant of mycosis fungoides (MF).
• pMF presents with clinical and histopathological pustule formation.
• The pathogenesis of pMF is not fully understood.

Purpose of the Study:

• To report a case of pMF triggered by systemic interferon-gamma (IFN-γ).
• To investigate the cytokine profile associated with IFN-γ-induced pMF.

Main Methods:

• Case report of a 71-year-old Japanese woman with MF.
• Clinical presentation, histopathological examination, and cytokine analysis (IL-8, IL-18, IL-23, IL-6) were performed.
• Treatment involved discontinuation of IFN-γ and antibiotic administration.

Main Results:

• The patient developed a generalized pustular eruption after IFN-γ administration.
• Histology showed spongiform pustules and CD30+ atypical lymphoid cells.
• Elevated serum IL-8, IL-18, IL-23, and IL-6 normalized upon remission.
• Pustules resolved rapidly after IFN-γ discontinuation.

Conclusions:

• Systemic IFN-γ can potentially trigger pustular mycosis fungoides.
• The IL-23/IL-17/IL-8 axis may play a critical role in pMF pathogenesis.
• This case highlights a novel therapeutic consideration and sheds light on pMF pathophysiology.