Psoriasis and Alopecia: Unveiling the Links

Psoriasis is a chronic inflammatory disease that may lead to scalp involvement, with a significant impact on patients' quality of life. Although most patients with scalp psoriasis do not experience alopecia, alopecia in the context of psoriasis is a multifaceted issue on which studies are limited.

The purpose of this review was to investigate different types of alopecia in psoriasis and the potential mechanisms.

A thorough literature review was performed, focusing on the relationship between psoriasis and alopecia areata (AA), drug-induced alopecia, and psoriatic alopecia.

Psoriasis and alopecia are related through several pathways. Regarding psoriatic alopecia, in most cases of psoriasis patients with scalp involvement, hair loss is attributed to telogen effluvium. In late-stage lesions, destruction of the hair follicle, perifollicular fibrosis, and free bare hair shafts in the dermis are revealed. However, hair loss in psoriasis is almost always non-scarring and reversible. In drug-induced alopecia, both conventional systemic treatments and biologics may cause hair loss in psoriatic patients. Specific side effects have been reported with TNF-α inhibitors and IL-17 blockers. TNF-α inhibitors may cause several types of alopecia: i) TNF-α inhibitor-associated psoriaticalopecia, ii) TNF-α inhibitor-associated AA, and iii) TNF-α inhibitor-associated lichen planopilaris. In concomitant psoriasis and alopecia areata, there is strong and convincing evidence that patients with psoriasis are at increased risk of developing AA, suggesting a complex interplay of autoimmune mechanisms.

Understanding the types and causes of alopecia in patients with psoriasis is crucial to proper management, thus highlighting the need for more research.