Necrotizing infundibular crystalline folliculitis: a clinicopathological study.

Abstract

Necrotizing infundibular crystalline folliculitis (NICF) is a folliculocentric disorder associated with filamentous crystalline deposits, enclosed by parakeratotic columns within the partly necrotic follicular ostium and infundibulum. There are only very few data published about this disorder of unknown origin. We sought to determine the clinicopathological features and pathogenetic aspects of NICF. Clinicopathological characterization of 9 patients with NICF and a second group of 7 patients with coincidental findings of NICF in the vicinity of epithelial skin neoplasms was conducted. Clinically, NICF is characterized by multiple waxy papules with predilection for the forehead (56%), neck, and back. Birefringent crystalline deposits were present in the follicular ostia and enclosed by parakeratotic columns in all cases. The necrosis of follicular epithelium was found in 89% and perifollicular neutrophilic infiltrate in 22% of the biopsy specimens. Both yeasts and gram-positive bacteria were identified within the affected follicles in 56% in the first group and 86% in the second group of coincidental NICF. This was a single-center retrospective study. NICF is both a distinct entity and an epiphenomenon in the context of other disorders. In regard to the common association with yeasts and gram-positive bacteria in the affected follicles, we hypothesize that NICF is pathogenetically linked to these organisms, which is supported by resolution of the lesions after topical or systemic antimycotic treatment.