Purpose or Case Report: The general pediatric radiologist is well aware of the classic scintigraphic findings of common malignancies. However, atypical presentations, appearances, and complications related to treatment and resultant immunosuppression may confound diagnosis. We present a series of interesting cases to help our non-nuclear medicine trained colleagues develop a systematic approach to nuclear medicine image interpretation in atypical cases.
Methods & Materials: Retrospective clinical case review series.

Our learning objectives include:
1) Review the normal biodistribution of commonly used radiotracers.
2) Review examples of the classic scintigraphic appearances of the common pediatric malignancies including neuroblastoma, leukemia, Hodgkins lymphoma, primary soft tissue and bone sarcomas.
3) Provide examples of the atypical nuclear medicine appearances of common pediatric tumors, focusing on an approach to imaging interpretation.
4) Demonstrate cases where a systematic approach to image interpretation and knowledge of expected routes of metastatic disease lead to the correct diagnosis.
Results: A series of interactive cases with nuclear medicine and correlative anatomic imaging are presented. Representative examples included are:
- Hodgkin’s lymphoma presenting as a lytic lesion of the iliac wing with intense FDG uptake, initially thought to represent Ewing sarcoma.
- Bone scan of an infant with Stage 4 S (Stage MS) neuroblastoma with abnormal uptake in numerous skin lesions.
- Pancreatic neuroblastoma in an infant.
- Diffuse anaplastic B-cell lymphoma, initially presenting as diffuse bowel wall thickening and mesenteric adenopathy with intense FDG uptake.
- Secondary leukemia following treatment for osteogenic sarcoma with marked FDG uptake in bone and kidneys in the context of a negative bone scan.
- Relapsed lymphoblastic leukemia with bilateral breast masses.
- Pathology confirmed osteosarcoma presenting with multiple pulmonary nodules and hilar adenopathy due to varicella pneumonia.
Conclusions: Nuclear medicine continues to play a pivotal role in the diagnosis, staging, and therapeutic response monitoring of pediatric malignancies. The pediatric radiologist must remain vigilant in the face of atypical appearances of common malignancies and their complications, which may result in unexpected findings on nuclear medicine imaging.