Track: Case Reports

Abstract:

A 13-year-old white male with a history of rosacea and keratosis pilaris (KP) presented with progressive left eyebrow hair loss over six months. His regimen included topical metronidazole, tacrolimus, desonide, zinc oxide sunscreen, and salicylic acid cleansers. On examination, there was diffuse thinning of the mid-to-lateral left eyebrow, facial macular erythema, and follicular keratotic papules on the cheeks, back, upper arms, and thighs. Hair pull test was negative; no definitive exclamation hairs were present. A punch biopsy of the affected brow was performed. Histopathologic evaluation (horizontal sections) revealed a reduction in follicle number to 10 total, all miniaturized. Three follicular units lacked both follicles and sebaceous glands, suggestive of follicular scars. The remaining seven units contained sebaceous glands, with six showing a single miniaturized follicle. One follicle demonstrated concentric lamellar fibroplasia and subtle epithelial-stromal blurring at the upper isthmus and lower infundibulum. Vacuolar interface alterations were absent. Clinicopathologic correlation supported a diagnosis of keratosis pilaris rubra faciei with associated scarring alopecia of the eyebrow. KP is a common disorder with multiple proposed subtypes, including KP rubra (marked by erythema without atrophy) and KP atrophicans (characterized by scarring and alopecia). This case exhibits overlapping clinical and histologic features of both, challenging current classification systems. Given the inflammatory and scarring components, our findings support recent proposals to consider these cases within the spectrum of lichenoid folliculitis, a broader term encompassing scarring inflammatory follicular disorders. This report highlights diagnostic challenges in KP variants and the importance of histopathology in guiding classification and management.

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Ophelia Pilkinton