Neuroblastoma Revealed by 99mTc - HMDP Bone Scan

Neuroblastoma is the second most common solid tumor in children, after central nervous system tumors. However, it is the most common malignant neoplasm in infants arising from neural tissue. Bone scintigraphy is typically performed for staging. We report the case of a 2.5-year-old child admitted for exploration of bone pain with deterioration of general condition, and a biological inflammatory syndrome. Bone scintigraphy, performed as part of his assessment 2 hours after injection of HMDP labeled with 99mTc, objectified the presence of heterogeneous uptake in the right hypochondrium, pushing back the homolateral kidney with extension to the vertebral plane, initially suggesting a retroperitoneal mass in contact with the upper pole of the kidney. It is associated with hyperfixations of the left orbital floor, the left humerus and the femurs. Metastatic neuroblastoma to the bone was then suspected. Computed tomography (CT) scans revealed the presence of a large intra- and retroperitoneal tumor invading the right renal hilum. 131I-MIBG scintigraphy confirmed the diagnosis suggested by the bone scan. Neuroblastoma is a difficult tumor to diagnose, given its rarity and the age of the children affected. 99mTc-HMDP bone scans can reveal indirect signs that can point toward the diagnosis of neuroblastoma.