Lipoma tumour. Light micrograph of a section through a lipoma from the heart. A lipoma is a benign tumour of fat cells (adipocytes). The fat cells are white here, as the fat they contained is removed by the preparation of the sample. Lipomas may occur anywhere in the body, and usually cause no harm. If the swelling tumour begins to damage other tissues by putting pressure on them, or if its size begins to disrupt the functioning of adjacent organs, it may have to be removed. Many lipomas are removed for cosmetic reasons as well. Magnification unknown.