Clinical and histopathological findings of skin metastasis show much variation. When skin metastatic carcinoma is diagnosed by histopathologic evaluation of the involved skin, the treatment must be started as soon as possible after immediate identification of the primary internal organ and the stage of the disease. Furthermore, one must investigate and infer the type of primary tumor from the previous history of internal malignancy, immunohistochemical findings and/or the results of some imaging. When a primary organ is confirmed, consultation with the department specializing in primary tumors is required for close inspection and treatment. When the primary origin is unidentified, detailed discussion is required about the diagnosis and therapeutic examination among the specialized departments including dermatology.