Should Malassezia’s Role in Seborrheic Dermatitis Be Reconsidered?

A recently published study in the Archives of Dermatologic Research, “More Yeast, More Problems?: Reevaluating the Role of Malassezia in Seborrheic Dermatitis,” explored whether Malassezia yeast plays a crucial role in the pathogenesis of seborrheic dermatitis, or if immune dysregulation and skin barrier disruption are more prominent factors.¹

Study author Raj Chovatiya, MD, PhD, clinical associate professor at the Rosalind Franklin University Chicago Medical School, founder and director of the Center for Medical Dermatology and Immunology Research, and Dermatology Times’ Fall 2024 Editor in Chief, spoke with Dermatology Times to further explore the clinical implications of the study and what comes next regarding updated research into the pathogenesis of seborrheic dermatitis.

Previous literature has pointed to Malassezia yeast as one of the key factors in the pathogenesis of seborrheic dermatitis, however according to Chang and Chovatiya, mixed data makes this theory more difficult to prove. One report from 2015 demonstrated increased Malassezia density in seborrheic dermatitis lesional skin compared to seborrheic dermatitis non-lesional skin and healthy controls.

In their analysis, Chang and Chovatiya referenced previous studies that proposed Malassezia’s involvement in seborrheic dermatitis as 3 key conditions: Malassezia colonization, sebaceous activity, and underlying host susceptibility, including genetics, epidermal barrier disruption, and immune sensitivity to metabolites. Based on previous research, “The most commonly proposed etiology of SD is based on this concept: Malassezia colonization on regions with high sebum secretion results in fatty acid production (secondary to yeast-driven sebum metabolism) that drives inflammation and disrupts the skin barrier in susceptible individuals,” wrote Chang and Chovatiya.

Newer research on the pathogenesis of seborrheic dermatitis now points to the influence of the cutaneous microbiome, according to the study authors. Chang and Chovatiya noted that inconsistencies across studies have made it difficult to credit Malassezia as the key factor in seborrheic dermatitis.

“For example, in at least two studies, Malassezia-genus composition at a species levels did not reveal significant differences between SD and non-SD patients,” wrote Chang and Chovatiya.

In terms of successful treatment strategies, Chang and Chovatiyanoted that topical corticosteroids have been successful in the treatment of seborrheic dermatitis, similar to inflammatory skin diseases, for their ability to improve erythema, itch, and scaling. According to Chang and Chovatiya, the inhibition of immune mediators and inflammatory cytokines with low-dose corticosteroids suggests that seborrheic dermatitis pathogenesis depends on inflammation and host immune response to drive clinical symptoms.

Roflumilast foam (Zoryve; Arcutis Biotherapeutics), a topical phosphodiesterase-4 (PDE-4) inhibitor, was approved for the treatment of seborrheic dermatitis in December 2023,² and according to the study authors, has shown immensely positive outcomes for patients with seborrheic dermatitis in clinical trials.

“Roflumilast is a highly potent PDE-4 inhibitor with up to 300-fold higher selectivity compared to apremilast and crisaborale in vitro, supporting the high efficacy and favorable safety and tolerability observed in clinical trials. In a phase 2a trial, SD patients had improved erythema, scaling, and itch symptoms, and the roflumilast foam was generally well-tolerated with minimal adverse effects,” wrote Chang and Chovatiya.

The study authors concluded that more Malassezia may not cause the development of seborrheic dermatitis, and that instead, newer studies show that “genetic factors that influence skin epidermal barrier and host immune activation may have a stronger contribution to the inflammation and skin disruption observed in SD than once thought.”

References

1. Chang CH, Chovatiya R. More yeast, more problems?: reevaluating the role of Malassezia in seborrheic dermatitis. Arch Dermatol Res. 2024;316(4):100. Published 2024 Mar 12. doi:10.1007/s00403-024-02830-7

2. FDA approves Arcutis’ ZORYVE (roflumilast) topical foam, 0.3% for the treatment of seborrheic dermatitis in individuals aged 9 years and older. News release. Arcutis Biotherapeutics. December 15, 2023. Accessed May 30, 2024. https://www.arcutis.com/fda-approves-arcutis-zoryve-roflumilast-topical-foam-0-3-for-the-treatment-of-seborrheic-dermatitis-in-individuals-aged-9-years-and-older/