Atypical intrathoracic rib in a pediatric patient requiring helical CT scan with 3-D reconstruction for diagnosis.

Intrathoracic rib is a rare congenital anomaly that is usually discovered incidentally. It represents a benign lesion but can mimic intrathoracic pathology, so it is important to recognize it to prevent further unnecessary investigation or intervention. Typically, the classic appearance allows diagnosis with confidence on the chest radiograph alone; however, an atypical appearance of an intrathoracic rib might limit the diagnostic capabilities of plain radiography, warranting further imaging with newer technologies. We report the case of an atypical presentation of an intrathoracic rib in an 8-year-old girl where radiographs were inconclusive and helical CT scan with 3-D reconstructions were required for a definitive diagnosis.