The porocarcinoma was excluded based on cellular morphology (absence of poroid cells); the clear-cell squamous cell carcinoma and the trichilemmal carcinoma were excluded due to the absence of epidermal connection, the presence of duct-like structures, and based on the immunohistochemistry panel (CK7+, CK8/18+; EpCAM and p63 only focal). This evidence concerns the gene KRT8 and eccrine porocarcinoma.