Xanthoma. Light micrograph of a section through a xanthoma. Xanthomas are benign (non-cancerous) fatty tumours that arise from connective tissue. They appear as yellow lumps anywhere on the body, but are most common around the joints and on the hands and feet. They are a common skin disorder in older adults especially those with elevated blood lipid (fat) levels. They may be a symptom of an underlying metabolic disorder such as diabetes. Treatment is aimed at the underlying problem. The growths can be surgically removed for cosmetic reasons, but may reappear.