{Reference Type}: Case Reports
{Title}: Recurrent inverse necrotizing infundibular crystalline folliculitis.
{Author}: Ibraheim MK;Storey L;North JP;
{Journal}: J Cutan Pathol
{Volume}: 51
{Issue}: 7
{Year}: 2024 Jul 2
{Factor}: 1.458
{DOI}: 10.1111/cup.14617
{Abstract}: Necrotizing infundibular crystalline folliculitis (NICF) is a rare type of necrotizing folliculitis. The disease typically manifests as folliculocentric papules arising in a seborrheic distribution. Only 23 cases exist in the literature. Most reported cases have arisen spontaneously, but a small number of drug-induced cases in the setting of epidermal-derived growth factor, vascular endothelial-derived growth factor, or PD-1 inhibitor therapy have been reported. Colonization by bacteria and/or yeast occurs frequently. The etiology remains unknown, but some suggest a complex interplay with an aberrant microbiome, sebaceous gland dysfunction, and perturbed EGFR signaling in follicular infundibula. Histopathologic findings include rupture of follicular epithelium, neutrophilic inflammation, and nodular cup-shaped crystal deposits. We present a case of spontaneous, recurrent NICF in an inverse pattern in the inguinal region.