Adult and infantile seborrheic dermatitis: update on current state of evidence and potential research frontiers.

Seborrheic dermatitis (SD) is a highly prevalent dermatological condition globally. The condition demonstrates bimodal presentation with what is commonly thought to be two subtypes: adult/adolescent seborrheic dermatitis (ASD) and infantile seborrheic dermatitis (ISD). Despite the common prevalence of ASD and ISD, there remains uncertainty around the underlying pathogenetic mechanisms, risk factors, and appropriate classification of the disease(s). This narrative review summarizes the current understanding of the epidemiology, presentation, and pathogenetic factors like epidermal barrier dysfunction, lipid abnormalities, and cutaneous microbiome for ASD and ISD. Elements such as immune responsiveness, neuroendocrine factors, and genetics in these disease states are also investigated. Throughout our review, we highlight shared features and discrepancies between ASD and ISD that are present in the literature and discuss potential avenues for future research that explore these disease states. We aim to contribute to the medical discourse on ASD and ISD and increase awareness of the need for additional research around these conditions, ultimately informing better targeting of therapeutics moving forward.