From the Guidelines
Seborrheic dermatitis is a common inflammatory skin condition that develops through a complex interaction between Malassezia yeasts, sebum production, and immune system responses, characterized by greasy yellowish scaling, itching, and secondary inflammation. The mechanism of seborrheic dermatitis involves the metabolism of sebum by Malassezia yeasts, producing irritating byproducts like oleic acid that damage the skin barrier, triggering an inflammatory response 1. This condition is more pronounced in patients with certain predisposing factors, including Down syndrome, HIV infection, and Parkinson's disease, as mentioned in the clinical practice guideline for acute otitis externa 1. Key factors that contribute to the development of seborrheic dermatitis include:
- Genetic predisposition
- Abnormal immune response to Malassezia yeasts
- Exacerbating factors such as stress, hormonal changes, and immunosuppression The treatment of seborrheic dermatitis typically involves the use of topical antifungal medications to reduce the amount of yeast present and topical anti-inflammatory medications to reduce inflammation and itch, as outlined in the study 1. The goal of treatment is ongoing management rather than permanent cure, with regular use of medicated shampoos and topical agents to control symptoms and prevent flare-ups.
From the FDA Drug Label
Mode of Action:In vitro studies suggest that ketoconazole impairs the synthesis of ergosterol, which is a vital component of fungal cell membranes. It is postulated that the therapeutic effect of ketoconazole in seborrheic dermatitis is due to the reduction of M. ovale, but this has not yet been proven. The mechanism of seborrheic dermatitis is not directly explained in the provided text, but the mode of action of ketoconazole in treating seborrheic dermatitis is thought to be related to the reduction of Malassezia ovale (formerly known as Pityrosporum ovale).
- Key points:
- Ketoconazole impairs the synthesis of ergosterol, a vital component of fungal cell membranes.
- The therapeutic effect of ketoconazole in seborrheic dermatitis is postulated to be due to the reduction of M. ovale.
- This mechanism has not yet been proven 2.
From the Research
Mechanism of Seborrheic Dermatitis
The mechanism of seborrheic dermatitis is complex and involves multiple factors, including:
- Malassezia species proliferation, which tends to occur on seborrheic areas, such as the scalp, face, chest, back, axilla, and groin areas 3
- Inflammation, which is a primary underlying pathogenic mechanism of the disease 3
- Sebocyte activity, skin microbiome dysbiosis, and immune factors, which contribute to the multifactorial etiology of seborrheic dermatitis 4
- Environmental triggers, such as fungal colonization by Malassezia spp., sebaceous gland activity, immunosuppression, endocrine, neurogenic, and iatrogenic factors, which can promote the development of seborrheic dermatitis in adults 5
Pathogenesis
The pathogenesis of seborrheic dermatitis involves:
- An inflammatory response to Malassezia species, which is a key factor in the development of the disease 3
- Skin microbiome alterations, which can contribute to the development of seborrheic dermatitis in children 5
- Excessive sebaceous gland activity, which can promote the development of seborrheic dermatitis in infants and adults 5
Treatment Implications
The mechanism of seborrheic dermatitis has implications for treatment, including:
- The use of topical antifungal and anti-inflammatory agents, which are commonly used to treat the disease 3
- The use of systemic antifungal drugs, such as itraconazole, which can be effective in treating seborrheic dermatitis 6
- The use of topical calcineurin inhibitors, which can be effective in treating seborrheic dermatitis, especially in cases that are refractory to topical treatment 4