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BB (ball bearing) bullet within the soft tissues of the forearm

Case contributed by Jeewaka Mohotti
Diagnosis almost certain

Presentation

The patient suffered a minor impact to his medial elbow and had an X ray to investigate for fractures. He also recalled being shot in the forearm with a BB gun as a child and had a small scar over the radial aspect of his proximal forearm.

Patient Data

Age: 45
Gender: Male

Supervising Authors:

  • A/Prof Roger Davies
  • Dr Jacqueline Kew
  • There is an incidental metallic 4.5 mm spherical foreign body within the soft tissue of the radial aspect of the proximal forearm approximately 20 mm deep to the skin. 
  • There is also soft tissue swelling at the postero-medial elbow joint likely representing a collection such as a hematoma. There is a fractured olecranon spur at the triceps insertion. 

Case Discussion

BB (ball bearing) guns are compressed air powered guns designed to shoot a metallic sphere similar to a shot pellet. Although not powered by gun powder, the projectiles still have significant penetrating power. The muzzle velocity of such weapons can be as high as 360 m/sec (traditional gunpowder pistols range from approximately 220 - 440 m/sec)1. There have been many published cases of soft tissue and even intra cranial penetration in the literature1,2,3. Measurement and composition can vary but most BB projectiles measure 4.5 mm in diameter and are composed of steel covered in zinc or copper to resist corrosion4

This patient was unaware that he still had the BB projectile embedded in his arm. He had been shot in the arm at close range as a child and had believed that the bullet had just deeply wounded his skin and rebounded away. He had a small scar on the skin overlying the location of the foreign body. 

This case serves to highlight the importance of considering plain radiographic imaging in patients with skin damage from BB guns even if there is only a small wound and the patient is unaware of a penetrating injury. 

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