The Diagnostic Utility of PRAME in Primary Cutaneous Dedifferentiated and Transdifferentiated Melanomas.

Melanomas show a wide spectrum of clinical, morphological, immunohistochemical, and molecular features, which can impact treatment and prognosis. Dedifferentiated and transdifferentiated melanomas (DTM) are defined as melanomas which have lost conventional melanocytic morphologic and immunohistochemical features, showing sarcomatous morphology and/or immunohistochemical staining of other cell lineages, and as such, can be mistaken for other entities such as collision tumors and undifferentiated spindle cell tumors. In this series, we highlight the utility of preferentially expressed antigen in melanomas (PRAME) in diagnosing undifferentiated/dedifferentiated melanomas.