Definition: Cystomyxoma is a medical condition that occurs when there are tumors in or around a cystic sac, which is a small sac of fluid-filled space. These tumors can cause swelling and pain in the area surrounding them, as well as affect normal functions of the organs within the body, including blood flow, breathing, and heart function. The most common types of cystomyxoma are benign (non-cancerous) and malignant (cancerous). Benign cystomyxomas