Mycobiome and Microbiome in Seborrheic Dermatitis

Seborrheic dermatitis (SD) is a chronic inflammatory skin disease in which scaling and erythema occur on various body parts, such as the scalp, eyebrows, nasolabial folds, and ears. Although it is a common skin disease, its pathogenesis remains unclear. It has various causes, including microorganisms and immune and nervous system abnormalities that act in a complex manner. The skin mycobiome/microbiome, an important factor in SD occurrence, is being actively studied. Among the skin microorganisms related to SD, Malassezia and Cutibacterium have been extensively studied. Recently, it was revealed that various microorganisms are related in several ways. The study of changes in mycobiome/microbiome involves comparing types and abundances of microorganisms and degrees of microbial diversity; patients and healthy individuals; the lesion and nonlesion areas; and affected body parts. Several studies on the mycobiome/microbiome associated with SD have shown relatively consistent results; however, some have revealed different outcomes. These variations occur because of differences in individuals, study groups, and sampling/study methodology. Therefore, further research is needed for the application the results of these studies in the treatment of SD.