Abstract

Pediatric cancers constitute a rare and heterogeneous group, representing less than 1% of all oncologic diagnoses. Within this classification, a subset is designated as 'very rare cancers', characterized by an annual incidence of fewer than 2 cases per million individuals. The diagnosis and management of these malignancies are particularly complex, owing to the paucity of clinical data and the inherent difficulties associated with conducting large-scale clinical trials. Imaging modalities are integral to the diagnostic process, staging, therapeutic planning, and response evaluation. While ultrasonography and magnetic resonance imaging remain the preferred first-line imaging techniques, F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has gained increasing recognition due to its ability to evaluate metabolic activity and tumor biology. FDG PET/CT provides valuable insights into tumor staging, restaging, differentiation of viable tumor tissue from necrosis or fibrosis, assessment of early treatment response, and surgical planning. Additionally, emerging radiopharmaceuticals, such as F-18 DOPA and Ga-68 DOTATATE, are being used for specific tumor subtypes based on their biological characteristics. PET/CT has demonstrated efficacy in detecting nodal and distant metastases, as well as in providing prognostic information through semiquantitative parameters such as maximum standardized uptake value, metabolic tumor volüme and total lesion glycolysis thereby informing multimodal therapeutic strategies. Nevertheless, limitations include diminished sensitivity for small pulmonary nodules, potential false positives due to physiological tracer uptake in pediatric populations, and the frequent requirement for sedation. This review discusses the role of PET/CT in the management of nasopharyngeal carcinoma, primary hepatic tumors, gastrointestinal malignancies, pancreatoblastoma, congenital hyperinsulinism, rhabdoid tumors, melanoma, and adrenocortical carcinoma, contextualized within current literature and supplemented with illustrative case studies.