Which of the following tumors is classified as a benign tumor of fat?

A lipoma is classified as a benign tumor of fat. This type of tumor consists of adipocytes, or fat cells, and typically appears as a soft, movable lump under the skin. Lipomas are the most common benign soft tissue tumors in adults and usually do not pose any significant health risk, although they can be removed surgically if desired for cosmetic reasons or if they cause discomfort.

Other tumor types mentioned, such as adenomas, fibromas, and hemangiomas, represent different tissue types and do not originate from fat tissue. An adenoma is typically a benign tumor of glandular tissue, a fibroma arises from fibrous connective tissue, and a hemangioma is a collection of blood vessels. Thus, only a lipoma specifically corresponds to the classification of a benign tumor of fat.