Follicular Psoriasis: A Case Report and Review of Literature.

INTRODUCTION: Psoriasis is an autoimmune papulosquamous disorder characterized by erythematous plaques. There are various subtypes, of which follicular psoriasis (FP) is an underreported entity, presenting as scaly follicular papules. Only a few cases have been reported, with limited dermoscopy findings having been described. This report aims to review the literature and emphasize the role of dermoscopy in the diagnosis of this rare variant.

CASE REPORT: A 31-year-old diabetic and obese male presented with symmetrical, itchy, scaly follicular lesions on his axillae, elbows, and knees for 6 months. Clinical differentials included follicular pityriasis rosea, pityriasis versicolor, or eczema. Dermoscopy revealed white scales and erythematous areas with multiple red dots present around hair follicles. Histopathology showed distended follicular infundibula with parakeratotic scales and psoriasiform changes, leading to a diagnosis of FP. Treatment with topical mometasone furoate and oral levocetirizine led to complete resolution within a month.

DISCUSSION: FP is a relatively uncommon subtype of psoriasis, manifesting differently in adults and juveniles. Although its exact cause remains unknown, hair follicle immune cells and/or keratin 17 (K17) may be involved. Dermoscopy can help distinguish it by revealing typical features including perifollicular white scales and vascular structures. Further epidemiological studies and long-term follow-up are needed for a comprehensive understanding of FP.