MyPath Melanoma is a diagnostic tool that distinguishes benign skin lesions from melanoma. It is a gene expression profiling (GEP) test that analyzes genetic information in a skin tissue sample. Its primary purpose is to support dermatologists and pathologists when visual and microscopic examinations are inconclusive, reducing diagnostic uncertainty. It provides objective information to aid diagnosis and inform management decisions for ambiguous melanocytic lesions.
Understanding Diagnostic Ambiguity in Skin Lesions
Diagnosing skin lesions can be challenging due to their ambiguous microscopic appearance. Some moles or growths resemble melanoma, making conclusive diagnosis difficult for pathologists. This uncertainty arises because benign lesions can share characteristics with malignant ones, creating a “gray area” where clear distinction is not immediately possible.
About 10-15% of biopsied melanocytic lesions are histopathologically ambiguous, meaning traditional methods cannot confidently classify them as benign or malignant. This leads to diagnostic discordance, with rates between expert dermatopathologists ranging from 14% to 38%. Misdiagnosis has consequences: under-treatment of melanoma can lead to tumor spread and increased mortality, while over-diagnosis might result in unnecessary surgery for benign lesions. Therefore, advanced diagnostic tools are needed for more objective information in these challenging cases.
The Science Behind MyPath Melanoma
MyPath Melanoma analyzes the expression of specific genes within a skin lesion sample. This process is known as gene expression profiling (GEP). It measures the expression levels of 23 genes: 14 involved in melanoma pathogenesis and 9 reference genes for normalization. These genes are selected because their activity patterns differ significantly between benign moles and malignant melanoma.
A small tissue sample, typically from an existing formalin-fixed, paraffin-embedded biopsy, is taken. RNA is then extracted from this tissue. Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), the expression levels of the 23 target genes are measured. An algorithm processes these measurements to generate a single numerical score, providing an objective classification.
Applying MyPath Melanoma in Clinical Practice
MyPath Melanoma is used as an ancillary test when microscopic examination of a skin lesion is inconclusive. It is useful for cases classified as atypical intraepidermal melanocytic proliferation, severely dysplastic nevi, or lesions where melanoma cannot be excluded. The test provides a numerical score (-16.7 to 11.1) categorized as “benign,” “indeterminate,” or “malignant.” Scores from -16.7 to -2.1 are considered benign, -2.0 to -0.1 are indeterminate, and 0.0 to 11.1 are malignant.
These results aid clinicians in making informed patient management decisions. For instance, a “benign” result can help avoid unnecessary re-excisions, while a “malignant” classification guides appropriate and timely treatment for early melanoma. MyPath Melanoma serves as an adjunct to traditional pathology, complementing rather than replacing the pathologist’s microscopic assessment. Its use increases diagnostic confidence and reduces ambiguous diagnoses, leading to more precise and personalized patient care.