Recurrent inverse necrotizing infundibular crystalline folliculitis

Area of Science:

• Dermatology
• Pathology

Background:

• Necrotizing infundibular crystalline folliculitis (NICF) is a rare necrotizing folliculitis.
• It typically presents as folliculocentric papules in a seborrheic distribution.
• Only 23 cases are documented, with most spontaneous and some drug-induced (EGFR, VEGF, PD-1 inhibitors).

Observation:

• NICF involves folliculocentric papules, often with bacterial/yeast colonization.
• Histopathology shows follicular epithelial rupture, neutrophilic inflammation, and crystalline deposits.
• This case presents spontaneous, recurrent NICF in an inverse inguinal pattern.

Findings:

• The etiology of NICF is unknown, possibly involving microbiome, sebaceous dysfunction, and EGFR signaling.
• Recurrent NICF in an inverse pattern is a novel presentation.
• The case highlights the varied clinical manifestations of NICF.

Implications:

• Further research into NICF etiology is warranted.
• Understanding triggers and pathogenesis may improve management.
• This case expands the known spectrum of NICF presentation.