Castle Biosciences (CSTL)

The company is best known for DecisionDx-Melanoma, a test designed to estimate the risk of recurrence or metastasis in patients with cutaneous melanoma. Castle also markets DecisionDx-SCC for high-risk cutaneous squamous cell carcinoma and MyPath Melanoma, which assists in evaluating melanocytic lesions that are difficult to classify with standard methods. Its portfolio extends beyond skin cancer through TissueCypher, a test used in Barrett’s esophagus to help predict the likelihood of progression to high-grade dysplasia or esophageal cancer.

Castle generates revenue primarily when it delivers diagnostic test reports to healthcare providers and receives payment from Medicare, commercial insurers, or other payers. The company’s model depends on clinical adoption, evidence generation, reimbursement coverage, and integration into physician workflows. As a diagnostics business, it operates at the intersection of oncology, dermatology, pathology, and precision medicine.

For investors, Castle Biosciences represents exposure to the growing use of molecular tools in risk stratification. Its distinguishing feature is a portfolio aimed at specific clinical decision points where improved prognostic information can influence patient care, rather than broad screening or commodity laboratory testing.