Query: Dissolving Foreign Body?
A year ago, I took an x-ray of a patient's foot which revealed an unrelated (to the chief complaint) metallic foreign body (FB) that appeared to be a pin. The FB was 2 cm in length and below the calcaneus, entering plantarly and angled dorsal medially. A year later, she presented with a chief complaint of heel pain. A second x-ray revealed the continued presence of the FB and palpation revealed it to be the source of pain. It had not moved from the original views.
Due to the patient's work schedule, removal was scheduled in two months. When the patient came in for removal, I took another x-ray with a grid to determine its exact location. To my shock, the FB was gone. It did not appear in any portion of the foot or ankle area. She also had no pain, but she thought it was because she was avoiding a lot of weight on the heel. She was asymptomatic when I had her walk barefoot on the floor and carpet.
Re-examination of my x-rays revealed the initial FB to be relatively solid. The x-ray taken a year later revealed very tiny indentations on the sides of the FB almost serrated. I surmised it was beginning to break down. My question is, "Has anyone had this occur, and what might the object have been, as metal is not likely to have "dissolved"?