A 74-year-old woman in Japan was being scanned to stage colon cancer when radiologists spotted a second problem: a 4-centimeter mass pressed against the top of her uterus, wrapped in a thin, eggshell-like shell of calcium. It looked like an old, degenerated fibroid, a common benign growth of the uterus.
It was something else. When surgeons removed the mass, they found a compacted core of tangled, thread-like fibers inside. Pathologists confirmed foreign material, and doctors diagnosed a gossypiboma, a mass that forms around a surgical sponge or similar material accidentally left in the body. Based on her history, they traced it to a cesarean section about 46 years earlier.
