Rash diagnostics: an update on the diagnosis of allergic rashes.

PURPOSE OF REVIEW: The purpose of this review is to summarize recent research regarding the diagnosis of allergic rashes and to suggest future directions for the promotion of accurate diagnosis and endotype specification.

RECENT FINDINGS: Multiple cohort studies demonstrate that with appropriate clinical evaluation, drug allergy labels can be removed in up to 90% of cases. Genetic tests can predict severe adverse cutaneous drug reactions in some cases and in vitro tests are being sought to identify causative drugs in others. Biomarkers to define endotypes of atopic dermatitis are needed to predict which patients will benefit from evolving targeted therapies. Hyperspectral imaging is a rapidly evolving technology in medical diagnostics; additional research is needed to demonstrate whether this promising technology can be used to distinguish allergic rashes and/or endotypes in atopic dermatitis.

SUMMARY: Diagnostic tools for the assessment of allergic rashes are primitive in that they frequently rely on challenges to ascertain whether suspected allergens were causative. Validated in vitro tests with high sensitivity and specificity for drug allergies would benefit the field, particularly in delayed type reactions, as would identification of any hyperspectral signatures that could identify endotypes in atopic dermatitis.