Tumbling Bullet Sign

Multiple

Post-traumatic bone cyst

Two sets of frontal and lateral radiographs, separated only by time, reveal the "tumbling bullet sign" – which is simply a bullet that changes its location and orientation within a solitary bone cyst. This sign serves two purposes: (1) it is documentation of the evolution of a solitary bone cyst as a corollary of trauma, and (2) it reveals the free movement of the foreign body within the confines of the lesion, establishing its cystic rather than solid nature. It is similar to the fallen fragment sign.

Taxin RN, Feldman R.: The tumbling bullet sign in a post-traumatic bone cyst. Am J Roentgenol Radium Ther Nucl Med 1975 Jan;123(1):140-3.