Cyst and Tumor
Cyst. A cyst is a sac that may be filled with air, fluid or other material. A cyst can form in any part of the body, including bones, organs and soft tissues. Most cysts are noncancerous (benign). Although cancers can form cysts.
Tumor. A tumor is any abnormal mass of tissue or swelling. Like a cyst, a tumor can form in any part of the body. A tumor can be benign or cancerous (malignant).