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Necrotizing infundibular crystalline folliculitis may be genetically linked to yeasts, gram-positive bacteria

Necrotizing infundibular crystalline folliculitis, a poorly understood disorder marked by waxy papules that often appear on the forehead, is possibly pathogenetically linked to microorganisms such as yeasts that resemble Malassezia and gram-positive bacteria such as Propionibacterium acnes, according to study results.

The Swiss, single-center, retrospective study evaluated 16 adult patients (10 men) with either necrotizing infundibular crystalline folliculitis (NICF) (n=9) or coincidental NICF in the areas near epithelial skin neoplasms (n=7). The investigators’ intent was to learn how this disorder develops as well as its genetic links.

The patients in the NICF group were aged 20 to 72 years; patients in the coincidental NICF arm of the study were aged 46 to 82 years.

All patients’ paraffin-embedded specimens were stained for hematoxylin-eosin, periodic acid–Schiff, and Brown-Brenn-Gram.

Of the patients in the NICF group, the investigators wrote that microscopic examination found “birefringent crystalline deposits within the follicular ostia enclosed by parakeratotic columns.” The follicular epithelium was necrotized in eight of the patients. Two of the patients showed infiltrates with perifollicular neutrophil granulocytes. Also found were yeasts and gram-positive bacteria in the follicles of 56% of this group.

In the coincidental findings of NICF group, all seven patients displayed “crystalline deposits within the follicular ostium enclosed by parakeratotic columns.” However, none of these patients showed follicular epithelium that was necrotized or any perifollicular neutrophils. In six of the patients, both yeasts and gram-positive bacteria were found in the follicles.

“The clinical response of NICF to topical or systemic antimycotic treatment underlines the pathogenetic role of microorganisms in NICF,” the researchers said.

They also proposed that because NICF is found mostly in a hair follicle’s ostia and not in the infundibular region, the name should be modified to “necrotizing ostial crystalline folliculitis.”