A benign or malignant neoplasm that affects the epididymis. Representative examples include epididymal adenomatoid tumor and epididymal adenocarcinoma. The disease is epididymal neoplasm (MONDO_0003283). Also known as: epididymis neoplasm, epididymis neoplasm (disease), epididymis tumor, epididymis tumour, neoplasm of epididymis, neoplasm of epididymus, tumor of epididymis, tumour of epididymis.