Puncture or impalement injuries can result in retained foreign bodies. Removal is warranted to prevent the foreign body from serving as a nidus for infection or producing a foreign-body granuloma. Unfortunately, identifying occult foreign bodies can be difficult. Ultrasonography, plain film radiographs, or metal detectors may be useful, depending on the composition of the material.1 In this case, we were able to confirm the presence of a metallic foreign body simply by applying a household magnet to the unbroken skin overlying a scar. This is an inexpensive way to identify superficial cutaneous metallic foreign bodies.
Aldrich NZ, Brodell RT. Confirmation of Cutaneous Metallic Foreign Bodies With a Magnet. Arch Dermatol. 2011;147(5):623-624. doi:10.1001/archdermatol.2011.105