Pigmented skin spots: Morphological characteristics, common causes, and treatment with cosmetic ingredients

Pigmented skin spots, a visible sign of aging, can significantly affect the appearance of facial skin. To elucidate their pathogenesis and support the development of novel cosmetic ingredients, this review summarizes the morphological characteristics of pigmented skin spots and the extrinsic and intrinsic factors contributing to their development. Additionally, it highlights the common cosmetic ingredients currently used for reducing hyperpigmentation. The relevant literature was collected by searching PubMed and Wanfang Data for studies focusing on pigmented spots and facial spots. Overall, the literature indicates that pigmented spots display distinct morphological characteristics, including specialized melanocyte dendrites, altered vascular architecture, abnormal keratinization, and immune cell infiltration. Mechanistically, their formation is driven by both extrinsic factors (e.g., sun exposure, skin microbiota, and particulate matter) as well as intrinsic factors (e.g., vascular abnormalities, chronic inflammation, and hormonal fluctuations). Thus, pigmented skin spots represent a complex biological system encompassing multiple types of cells and molecular mediators, regulated by diverse environmental and physiological factors. Given their intricate microenvironment conditions and multifactorial etiology, a systematic and comprehensive investigation of pigmented spots is warranted. Such research could inform the development of cosmetic ingredients with targeted and multitargeted actions, enabling the more effective reduction of pigmented skin spots.