Eccrine porocarcinoma, also known as porocarcinoma (PC) and malignant eccrine poroma, is very rare and is known to arise from the cutaneous intraepidermal ducts of the sweat glands. Its etiology is not well understood; however, some studies suggest that PC tumors originate from benign eccrine poroma. Recently, several gene alterations have been reported in PC that can reveal mechanisms of the oncogenic process. Since the clinical and histopathological findings of PC are variable, PC is difficult to diagnose precisely, especially when the histology resembles that of cutaneous squamous cell carcinoma or poroma. Immunohistochemical staining with carcinoembryonic antigen and epithelial membrane antigen may help to distinguish PC from other tumors. The standard treatment for local PC is wide local excision. The prognosis of patients with metastatic PC is poor, with mortality rates of approximately 60–70%. The efficacy of radiation and chemotherapy for metastatic PC is limited; however, immunotherapy with pembrolizumab, a programmed cell death protein 1 inhibitor, could be a promising treatment. This review focuses on the history, pathogenesis, pathological features, diagnosis, and treatment of eccrine porocarcinoma.