Pediatric posterior fossa incidentalomas

Purpose: Pediatric brain incidentalomas are increasingly being diagnosed. As the posterior fossa (PF) is the location of most brain tumors in children, lesions of this region are of special interest. Currently, the natural history of incidental lesions in the PF is unknown. We present our experience treating such lesions. Methods: A retrospective study was carried out in two large tertiary pediatric centers. Patients were included if they had an incidental PF lesion suspected of being a tumor, and diagnosed before the age of 20 years. We analyzed treatment strategy, pathology, and outcome of operated and non-operated cases. Results: Seventy children (31 females) with a mean age of 8.4 ± 6.1 years were included. The three most common indications for imaging were headaches (16, assumed to be unrelated to the lesions), workup of unrelated conditions (14), and unspecified reasons (14). Twenty-seven patients (39%) were operated immediately, and 43 followed, of which 12 were eventually operated due to radiological changes, 28.9 ± 16.2 months after diagnosis. The most commonly found pathology was pilocytic astrocytomas (21 of 39 operated cases). Almost 10% were found to be malignant tumors including medulloblastomas (5) and ATRT (1). Conclusion: Incidental PF lesions in children include both benign and malignant tumors. While certain lesions may be followed, others may require surgical treatment. Specific treatment decisions are based on initial radiological appearance, change in radiological characteristics over time, location, and evolving symptoms. The surgical risks must be balanced vis-à-vis the risk of missing a high-grade tumor and the very rare risk of malignant transformation.