Castle Biosciences is a molecular diagnostics company that develops and operates multi-analyte tests to guide treatment decisions in dermatology, gastroenterology, and ophthalmology. The company's core offering includes proprietary tests such as DecisionDx-Melanoma and DecisionDx-SCC for melanoma and squamous cell carcinoma risk stratification, TissueCypher for Barrett's esophagus progression prediction, and diagnostic tests for uveal melanoma and atopic dermatitis treatment selection, supported by substantial clinical evidence and algorithmic analysis. Revenue derives primarily from third-party payers—Medicare and commercial insurers—which reimburse at Medicare Advanced Diagnostic Laboratory Test rates, with the company operating CLIA-certified laboratories serving all 50 states.