KRT20 and basal cell carcinoma: This right flank basal cell carcinoma specimen was re-examined and immunohistochemical stains were performed following discovery of the lung metastases; the tumor cells were negative for synaptophysin, chromogranin, and cytokeratin 20 by immunohistochemistry, findings which argue against the possibility of a cutaneous neuroendocrine carcinoma (Merkel cell carcinoma), (Figure 3).