Diagnosing Melanoma

An early and accurate diagnosis is the first step in providing patients with the treatment they need. 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.1-4 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 . 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.” – Lorenzo Cerroni, et al5

Only 10-15 percent of patients with advanced melanoma survive more than five years, so an early diagnosis – when the cancer is more treatable – is critical.

melanoma 5- and 10-year survival rate by cancer stage

To date, the best option for diagnosing melanoma has been histopathological examination of skin biopsies. Even the most experienced dermatopathologists encounter situations in which distinguishing between a benign nevus and malignant melanoma can be difficult.6-8

Using myPath® Melanoma to Assist in Melanoma Diagnosis9

Myriad myPath Melanoma can assist healthcare professionals in distinguishing malignant melanoma from benign nevi. If your patient has a suspicious skin lesion, Myriad myPath Melanoma can help you make more informed decisions about the best course of treatment.

The myPath Melanoma test result is a single numerical score that classifies melanocytic lesions as likely benign, likely malignant, or indeterminate. The expression of each of the 23 genes that comprise the signature is measured by qRT-PCR. An algorithm is then applied that assigns a weight to each of the signature components and establishes a threshold value. The algorithm generates a single numerical score which is plotted on a scale that ranges from -16.7 to +11.1. This range was established based on the scores produced by the 437 melanocytic lesions analyzed in the first clinical validation study, and scores within this range will be reported. Scores outside of this range cannot be considered valid and will not be reported.

Distribution of myPath Melanoma Scores

  • Scores between -16.1 and -2.1 are reported as ‘likely benign’
  • Scores between -2.0 and -0.1 are reported as ‘indeterminate’
  • Scores between 0.0 and +11.1 are reported as ‘likely malignant’

Get Started With myPath Melanoma Testing

References

1. Shoo BA, Sagebiel RW, Kashani-Sabet M. Discordance in the histopathologic diagnosis of melanoma at a melanoma referral center. Journal of the American Academy of Dermatology. 2010;62(5):751-6.

2. Veenhuizen KC, De Wit PE, Mooi WJ, et al. Quality assessment by expert opinion in melanoma pathology: experience of the pathology panel of the Dutch Melanoma Working Party. J Pathol. 1997;182(3):266-72.

3. Farmer ER, Gonin R, Hanna MP. Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol. 1996;27(6):528-31.

4. McGinnis KS, Lessin SR, Elder DE, et al. Pathology review of cases presenting to a multidisciplinary pigmented lesion clinic. Archives of dermatology. 2002;138(5):617-21.

5. Cerroni L, et al. Melanocytic tumors of uncertain malignant potential. Am J Surg Pathol 2010;34(3).

6. Shoo B, et al. Discordance in the histopathologic diagnosis of melanoma at a melanoma referral center. Am Acad Dermatol 2010;620:751-6.

7. Lodha S, et al. Discordance in the histopathologic diagnosis of difficult melanocytic neoplasms in the clinical setting. J Cutan Pathol 2008;35:349–352.

8. American Cancer Society. www.cancer.org. Accessed December 2013.

9. Clarke L et al. Clinical validation of a gene expression signature that differentiates benign nevi from malignant melanoma J Cutan Pathol 2015; 42:244-252.