Abnormal FDG and MIBG Activity in the Bones in a Patient With Neuroblastoma Without Detectable Primary Tumor Wei Zhang, MD,*† Hongming Zhuang, MD, PhD, FACNM,* and Sabah Servaes, MD* Abstract: Neuroblastoma is among the most common extracranial solid tumors in pediatric patients and typically arises anywhere from the neck to pelvis but most commonly in the adrenal glands. It is extremely rare for a patient to have extensive metastases from neuroblastoma without primary tumor being identified. We present a 3-year-old with widespread bone and bone marrow involvement of the disease revealed on both FDG PET/CT and MIBG scan, which was pathologically proven as neuroblastoma. How- ever, extensive imaging did not detect primary tumor anywhere. Key Words: FDG, MIBG, neuroblastoma, PET/CT (Clin Nucl Med 2016;41: 632–633) REFERENCES 1. Podoloff DA. PET/CT and occult primary tumors. J Natl Compr Canc Netw . 2009;7:239–244. 2. Graute V, Jansen N, Sohn HY, et al. 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Increased bone marrow activ- ity on F-18-FDG PET/CT in granulocyte colony stimulating factor produc- ing anaplastic thyroid carcinoma. Clin Nucl Med. 2010;35:103–104. 19. Balink H, Nabers H, Kibbelaar RE. High F-18 FDG uptake in bone marrow by cytokines secreting ectopic mucoepidermoid carcinoma. Clin Nucl Med. 2009;34:823–824. 20. Takahashi S, Kuwabara K, Sawafuji M, et al. F-18 FDG PET imaging in a patient with granulocyte colony stimulating factor producing pulmonary pleomorphic carcinoma. Clin Nucl Med. 2008;33:555–557. Received for publication November 20, 2015; revision accepted December 2, 2015. From the *Department of Radiology, Children's Hospital of Philadelphia, Uni- versity of Pennsylvania Perelman School of Medicine, Philadelphia, PA; and †Department of Nuclear Medicine, Chinese Academy of Medical Sci- ences and Peking Union Medical College Hospital, Beijing, People’ s Repub- lic of China. Conflicts of interest and sources of funding: none declared. Correspondence to: Hongming Zhuang, MD, PhD, Department of Radiology, Children’ s Hospital of Philadelphia, 34th & Civic Ctr Blvd, Philadelphia, PA 19104. E-mail: zhuang@email.chop.edu. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/16/4108–0632 DOI: 10.1097/RLU.0000000000001134 FIGURE 1. A 3-year-old boy presented with lethargy and periorbital ecchymoses. An unwitnessed head trauma was suspected, and a head CT was performed for further evaluation. The images did not reveal any subdural hematoma or skull fracture. Unexpectedly, there were osseous lesions involving the bilateral mandibular rami and the greater wing of the sphenoid bones with associated speculated periosteal new bone formation (arrows). Osseous metastases from an unknown tumor were diagnosed based on CT findings. INTERESTING IMAGE 632 www.nuclearmed.com Clinical Nuclear Medicine • Volume 41, Number 8, August 2016 Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.