Localization of recurrent phosphaturic mesenchymal tumor in a child using 18FDG-PET/CT and 111In-Octreoscan

A 13 year old boy with history of phosphaturic mesenchymal tumor of the proximal tibia, resected two years previously, developed biochemical evidence of recurrence. Radiographs and MRI of the resection site failed to identify the site of recurrence. 18FDG-PET/CT and 111In-Octreoscan were performed concurrently, and both identified a site of abnormal uptake adjacent to the resection margin in the proximal tibia. Phosphaturic mesenchymal tumor is a pediatric rare tumor associated with tumor-induced osteomalacia. This unique case demonstrates the utility of nuclear medicine imaging in localizing recurrence of an uncommon tumor, and the potential role of 18FDG-PET/CT in managing these patients.