Immunohistochemical investigation of MCC cases (Figure 1) reveals the expression of both epithelial (pancytokeratin AE1/AE3) and neuroendocrine markers such as chromogranin A (11), synaptophysin (11), CD56 (10) and INSM1 (insulinoma-associated 1) (12). Here, INSM1 is linked to Merkel cell skin cancer.