Aden- means gland and -oma means tumorous growth. Together, an adenoma is a tumorous growth of glandular tissue. Therefore, a tumorous growth involving the sebaceous glands is called a sebaceous adenoma. In cases of maligancies, it can either be a carcinoma (arising from the epithelium) or a sarcoma (arising from the stroma). If the sebaceous gland tumor turns out to be malignant, it is now called a sebaceous adenocarcinoma as it is a cancer arising from glandular epithelium.