Cutaneous metastases of non-cutaneous neuroendocrine neoplasms: A histopathologic review of 15 cases.

While immunohistochemical stains, in particular CK20, CK7, and TTF-1, are integral in the workup of confirming the origin of neuroendocrine tumors found in the skin, results vary and are often non-specific for a single primary site. Therefore, complete radiologic imaging as well as clinical correlation should be recommended to further aid in the identification of a non-cutaneous primary neoplasm.