Abstract:

PRAME (preferentially expressed antigen in melanoma) immunohistochemical stain has been studied in varies types of benign nevi and melanomas. In a previous study, the frequency of PRAME nuclear immunoreactivity in primary and metastatic melanoma was reported to be 83.2% and 87%, respectively. Of the 140 cutaneous melanocytic nevi, 86.4% were completely negative for PRAME in the same study (4/40 common acquired nevi expressed 1+, 10/60 dysplastic nevi expressed 1+, 1/10 Spitz nevi expressed 1+, 2/15 traumatized/recurrent nevi expressed 1-2+ and none of the 10 blue nevi or 3 deep penetrating nevi expressed PRAME). In this study, we examined PRAME expression in 15 melanocytic lesions including: common blue nevi, atypical/cellular blue nevi and deep penetrating nevi. PRAME was not expressed in common blue nevi 0% (5 cases were studied). One of five (20%) atypical blue nevi showed weak nuclear expression (score of 1-2+). The atypical melanocytes showed a prominent epithelioid morphology. Two of five deep penetrating nevi (40%) showed weak nuclear expression (score of 1-2+). PRAME can be useful in supporting diagnosis of melanoma over benign nevi. However, given the relative high expression of PRAME in this small number of deep penetrating nevi in our study, caution should be taken in using PRAME to support diagnosis of melanoma in this setting.

Financial Disclosure:
No current or relevant financial relationships exist.

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Michael Greas, MBBCh