This 42-year old male presented with a large mass on left-side of the chest wall. The mass was noticed 5 years back and was growing particularly rapidly since last 1 year. Surprisingly, the only complaint was discomfort and interference during routine work. On CT, the mass appears to be arising from the anterolateral aspect of the ribs and shows dense matrix calcifications (popcorn calcification). Additional findings that may be seen include endosteal scalloping, moth-eaten or permeative appearance in high-grade lesions, cortical remodeling, and periosteal reaction. Case produced with permission, courtesy of Dr. Frank Gaillard. Radiopaedia. Complete case is here.