Usefulness of positron emission tomography in the differentiation between tumor and infectious lesions in pediatric oncology: a case report

Background: Sometimes, in pediatric oncology, it is difficult to differentiate the relapse of primary tumor from other diagnoses such as post-ischemic lesions or fungal abscess, without performing an organ biopsy. In addition, patients frequently are not under clinical conditions to be biopsied, mainly due to febrile neutropenia. A growing number of studies has focused on the use of Positron emission tomography/computed tomography with 18 Fluorodeoxyglucose ([F-18]FDG-PET/CT) to distinguish tumor relapse from infectious lesions in patients with febrile neutropenia. Case presentation: This case report describes a 6 years-old girl with febrile neutropenia during the treatment of neuroblastoma. Blood culture showed Candida sp. Abdominal ultrasonography revealed multiple unspecific hypoechoic areas of variable sizes in spleen, which might be either tumor or Candida-induced abscesses. [F-18]FDG-PET/CT was performed to help the diagnosis and revealed small splenic lesions highly suggestive of disseminated candidiasis. Patient was then treated with systemic antifungal agent. After the recovery from febrile neutropenia, a spleen biopsy was performed, confirming the diagnosis of fungal abscess. Due to the small size of lesions, modalities such as ultrasonography, CT and magnetic nuclear resonance were not able in distinguishing tumor relapse from infectious lesions. Conclusion: This case provides an excellent example in which the use of [F-18]FDG-PET/CT is valuable in helping to localize potential sites of disseminated fungal infection to be diagnosed within clinical context. [F-18]FDG-PET/CT seems to have a role in the evaluation of pediatric patients with febrile neutropenia.