<b>Conclusion:</b> The identification of additional lesions outside the R-FOV (eyes to thighs) using <sup>18</sup>F-FDG PET/CT has no impact in the definition of the clinical stage of disease and minimal impact in the treatment definition of patients with pediatric lymphoma.
18-Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) is currently the criterion standard of lymphoma imaging and recommended through all stages of Hodgkin lymphoma management.
FDG PET/CT has optimum negative predictive value compared with BMB in detection of bone marrow infiltrations in pediatric lymphoma with upstaging cases missed with BMB.
FDG uptake in the lymph nodes was observed in 53.3% of the patients with lymphoma and 43.3% of the patients without lymphoma, with no difference in the number of sites, uptake pattern, or mean SUVmax.
Although <sup>18</sup>F-FDG has proved useful in the management of patients with lymphoma, the specificity of <sup>18</sup>F-FDG uptake has been critically questioned, and is not without flaws.
Although positron emission tomography with 18F-fluoro-2-deoxyglucose (FDG-PET/CT) has been recommended as the method of choice for lymphoma staging, it has limited availability in several countries, therefore, studies comparing whole-body magnetic resonance imaging (MRI) to conventional staging methods or to FDG-PET/CT are an important tool to establish whole-body MRI as an alternative to these methods.
Burkitt's lymphoma is a lymphoma with unclear metabolic behavior at 18F-FDG-PET/CT and no validated criteria in treatment evaluation and prediction of outcome exist.
Comparisons of CT features and <sup>18</sup>F-FDG metabolic indices between benign and malignant entities, as well as among primary and secondary malignancies and lymphoma, were performed.
Except for SUVmin (<i>p</i>=0.971), the averages of FDG uptake metrics of lymphoma were significantly higher than those of carcinoma (<i>p</i> ≤ 0.001), with the following median values: SUV<sub>mean</sub>, 4.75 versus 2.38 g/ml (<i>P</i> < 0.001); SUV<sub>std</sub>, 2.04 versus 0.88 g/ml (<i>P</i>=0.001); SUV<sub>max</sub>, 10.69 versus 4.76 g/ml (<i>P</i>=0.001); SUV<sub>peak</sub>, 9.15 versus 2.78 g/ml (<i>P</i> < 0.001); TLG, 42.24 versus 9.90 (<i>P</i> < 0.001).
F-FDG PET/CT showed hypermetabolic foci in the liver, spleen, and bone marrow, as well as multiple FDG-avid lymph nodes, which were highly suggestive of lymphoma.
However, several pitfalls may occur during or after treatment, because of the nonspecificity of F-FDG for lymphoma disease and treatment as immunotherapy, thus possibly induces misinterpretation and wrong treatment decision.
In this case, we aim to highlight this interesting FDG PET/CT imaging finding, which can serve as a clue allowing one to strongly suggest lymphoma as the leading diagnosis.
Interim and posttreatment sequential FDG PET/CT scans revealed a residual splenic mass showing markedly intense FDG uptake suspected of a residual viable lymphoma.