The Impact of PRAME Expression on Breslow Depth in Melanoma Arising in Dysplastic Nevi in a Large Multi-State Dermatology Group

Background: PRAME immunohistochemistry has been reported to be positive in at least 83.2% of invasive melanomas while being positive in no more than 13.6% of benign nevi. Melanoma may arise within pre-existing nevi or dysplastic nevi and PRAME could potentially have an effect on the measured Breslow depth. Objective: We performed a retrospective review of invasive melanoma cases diagnosed over a 4 year period to evaluate if the use of PRAME had an impact on Breslow depth. Methods: Diagnostic reports were reviewed to separate out cases of invasive melanoma that arose in precursor nevi or dysplastic nevi. The final sample size is 152 cases. Results: The average melanoma depth in the PRAME group was 0.51 mm, while being 0.68 mm in the no PRAME group (p<0.05). The pathologic stage was unchanged in all cases. Limitations: The pathology reports were made by multiple dermatopathologists and therefore reporting of precursor nevi on the reports may not be entirely uniform. Conclusion: PRAME does impact the Breslow depth of invasive melanoma when arising in precursor nevi, but significant alterations in the pathologic stage were not observed.