Melanoma is a potentially fatal form of skin cancer. Early and accurate diagnosis of melanoma is critical for long-term survival.1
The analysis of biopsied tissue using a microscope (histopathology) has long been the standard of care for melanoma diagnosis. While it is adequate for diagnosis in most cases, evidence suggests that approximately 10-15% of biopsied melanocytic lesions may be histopathologically ambiguous.2-5 In these situations, microscopic examination may reveal a few features that are characteristic of melanoma but others that are more typical of a benign nevus (‘mole’). As a result, even experienced dermatopathologists occasionally disagree as to whether a given melanocytic lesion is benign or malignant.
Melanocytic lesions continue to pose significant interpretive problems to histopathologists.
The myPath Melanoma test measures 23 genes for which expression patterns differ between malignant melanoma and benign nevi. These genes are involved in cell differentiation, cell signaling, and immune response signaling.
The genes include:
- PRAME a single gene involved in cell differentiation
- S100A7, S100A8, S100A9, S100A12 and PI3, a group of genes involved in multiple cell signaling pathways
- CCL5, CD38, CXCL10, CXCL9, IRF1, LCP2, PTPRC and SELL involved in tumor immune response signaling
- Nine housekeeping genes that are measured to normalize RNA expression for analysis
Housekeeping genes included: CLTC, MRFAPI, PPP2CA, PSMA1, RPL13A, RPL8, RPS29, SLC25A3, and TXNLI
An algorithm is applied that combines the measurements of gene expression, assigns a weight to each gene component, and establishes a threshold value.
The result is a single numerical score that classifies a melanocytic lesion as ‘likely benign’, ‘likely malignant’, or ‘indeterminate’.