Congenital atlas abnormalities are rare - often asymptomatic - findings, not requiring any specific treatment. They are frequently discovered, by chance, in trauma patients, in the course of the radiological work flow at the Emergency Department. In these cases they may represent a diagnostic challenge, since physicians are expected to differentiate them from complex C1 fractures (isolated Jefferson's fractures or associated with Anderson and d'Alonzo's fractures) requiring surgical treatment. Although difficult to identify, a correct diagnosis is mandatory in order to optimize the patient's treatment. In this article we report a case of congenital atlas abnormality, and discuss the tips and tricks to make a correct differential diagnosis through the most appropriate clinical and radiological work flow.