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Re-Evaluating the Role of Malassezia in Seborrheic Dermatitis
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- This review challenges the long-held belief of Malassezia species as the primary cause of seborrheic dermatitis, citing a lack of consistent correlation. Instead, it is suggested that immune dysregulation and skin barrier dysfunction, akin to atopic dermatitis, play more significant roles. The review advocates re-evaluating the etiology of seborrheic dermatitis to better understand its pathogenesis and develop targeted treatments.
- This review suggests that the pathogenesis of seborrheic dermatitis centers more on immune dysregulation and skin barrier dysfunction rather than Malassezia as a primary causative agent.
abstract
This abstract is available on the publisher's site.
Access this abstract nowSeborrheic dermatitis (SD) is an inflammatory skin disorder and eczema subtype increasingly recognized to be associated with significant physical, psychosocial, and financial burden. The full spectrum of SD, including dandruff localized to the scalp, is estimated to affect half of the world's population. Despite such high prevalence, the exact etiopathogenesis of SD remains unclear. Historically, many researchers have theorized a central, causative role of Malassezia spp. based on prior studies including the proliferation of Malassezia yeast on lesional skin of some SD patients and empiric clinical response to antifungal therapy. However, upon closer examination, many of these findings have not been reproducible nor consistent. Emerging data from novel, targeted anti-inflammatory therapeutics, as well as evidence from genome-wide association studies and murine models, should prompt a reevaluation of the popular yeast-centered hypothesis. Here, through focused review of the literature, including laboratory studies, clinical trials, and expert consensus, we examine and synthesize the data arguing for and against a primary role for Malassezia in SD. We propose an expansion of SD pathogenesis and suggest reframing our view of SD to be based primarily on dysregulation of the host immune system and skin epidermal barrier, like other eczemas.
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More yeast, more problems?: reevaluating the role of Malassezia in seborrheic dermatitis
Arch Dermatol Res 2024 Mar 12;316(4)100, CH Chang, R ChovatiyaFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Seborrheic dermatitis and Malassezia
Before reading this review on the role of Malassezia in seborrheic dermatitis, I really didn’t know what role yeast plays in seborrheic dermatitis. However, after reading it, well, I still don't know what role yeast might play in seborrheic dermatitis.
A biopsy of seborrheic dermatitis makes it clear that inflammation is important, treating the inflammation makes the disease better, and inflammatory genes are linked to the disease. However, treating for yeast can make the disease better, too. Seeing disease improvement with topical anti-inflammatory medication does not necessarily imply that yeast is not important, as these topical anti-inflammatory medications contain preservatives that may reduce skin microorganism populations. Seeing disease improvement with topical antimicrobial medication does not necessarily imply that yeast is critical, as topical antimicrobial medications might have anti-inflammatory effects. Seeing a lack of relationship between yeast numbers and inflammation may not be meaningful if the inflammation is an allergic reaction to the yeast; an allergic reaction might be insensitive to the quantity of the organisms. Teasing out which comes first — inflammation, barrier dysfunction, or Malassezia — seems about as much of a Gordian knot as whether the chicken or egg came first. It seems doubtful that seborrheic dermatitis is even a single disease; it may be that genetic tendency toward inflammation is more critical in some patients, while lifestyle, microorganisms, or different combinations of all of these are more critical in others.
The clinically important bottom line is that I don't care. If I have safe, effective, low-cost anti-inflammatory or antimicrobial treatments that work, great! The existence of a safe, effective, high-cost anti-inflammatory treatment does not seem to be a good reason to change our beliefs on inflammation as the cause of the disease.