Ghost Tumors of the Central Nervous System: Definition, Clinical Implications, and Proposal of Classification

BACKGROUND: A ghost tumor (GhT) is a space-occupying lesion with radiologic features consistent with the diagnosis of tumor that on further investigation is revealed not to be a tumor, although definitions in the literature are inconsistent, and the incidence of GhT remains undefined. METHODS: A review of the pertinent literature was performed to identify pediatric patients in whom a misleading initial diagnosis of space-occupying lesion was described. Analysis of the differentiating features of the final diagnosis and related clinical and radiologic issues was performed. RESULTS: GhT may be categorized as follows: GhT I, lesions spontaneously disappearing during follow-up, also known as "vanishing tumors"; GhT II, nonneoplastic space-occupying lesions showing a tumor appearance, also known as "tumor-like lesions"; GhT III, anatomic variants of normal structures mimicking a tumor, also defined as "false tumors." The most deceptive conditions and critical points in the differential diagnosis of these cases were discussed. CONCLUSIONS: GhT is an entity with significant implications in regard to treatment and outcome. In this context, the integration of clinical and radiologic clues is crucial for a careful differential diagnosis and a consistent diagnostic approach, which is necessary for adequate decision making regarding management. A thorough radiologic work-up is mandatory. Atypical radiologic images should raise a high level of suspicion, including incidental lesions, which are encountered with increasing frequency in daily practice as a result of greater access to radiologic examinations, increasing sensitivity of imaging, and the impact of defensive medicine. A wait-and-see policy should be considered whenever indicated.