Necrotizing infundibular crystalline folliculitis: a clinicopathological study

Area of Science:

• Dermatology
• Pathology
• Microbiology

Background:

• Necrotizing infundibular crystalline folliculitis (NICF) is a rare folliculocentric disorder.
• Characterized by filamentous crystalline deposits within the follicular ostium and infundibulum.
• The exact origin of NICF remains largely unknown.

Purpose of the Study:

• To elucidate the clinicopathological features of NICF.
• To investigate potential pathogenetic aspects of NICF.
• To differentiate NICF as a distinct entity versus an epiphenomenon.

Main Methods:

• Retrospective analysis of 9 patients with NICF.
• Inclusion of 7 additional patients with NICF adjacent to skin neoplasms.
• Clinicopathological characterization of biopsy specimens.

Main Results:

• NICF presents clinically as waxy papules on the forehead, neck, and back.
• Birefringent crystalline deposits and follicular ostium parakeratosis were consistent findings.
• Microbial presence (yeasts, gram-positive bacteria) identified in affected follicles in a majority of cases.
• Follicular epithelial necrosis observed in 89% of specimens.

Conclusions:

• NICF can be both a distinct condition and associated with other disorders.
• A pathogenic link between NICF and microbial organisms (yeasts, gram-positive bacteria) is hypothesized.
• Treatment with antimycotics showed resolution, supporting the proposed etiology.