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 …