Tumor necrosis factor-α inhibitor-induced follicular psoriasiform eruption

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.

Atypical Dermatitis Herpetiform and Scalp Psoriasis in Ulcerative Colitis Patient Treated With Adalimumab

Adalimumab is a blocker of tumor necrosis factor (TNF)-alpha with established efficacy in the treatment of ulcerative colitis. However, literature indicated that adalimumab can, occasionally, induce paradoxical psoriasis reactions and, very rarely, dermatitis herpetiformis. We present a unique case of a 26-year-old female patient who developed a combination of dermatitis herpetiformis and scalp psoriasis paradoxically as a result of adalimumab treatment for ulcerative colitis. To the best of our knowledge, this is the first case of such a combination within the context of adalimumab therapy. The etiopathological underpinning of such a reaction remains elusive but is speculated to be complex and involves the interaction of several immunological and dermatological mechanisms. Adalimumab therapy is associated with a genuine risk for the development of paradoxical psoriasis and dermatitis herpetiformis. We, through this case report, added to the evidence confirming such an association. Clinicians should follow these potential adverse effects and make every effort to warn patients of their likelihood.