Figure 10a. Tonsillar lymphoma in a 20-year-old man with Burkitt lymphoma of the abdomen who was referred for posttherapy evaluation. Axial PET scan (b) demonstrates intense FDG uptake in the region of the tonsils with minimal asymmetry (arrows), a finding that is suspicious for extranodal lymphoma in the regional lymphatic tissues. (a, c) Axial CT (a) and PET-CT fusion (c) images help confirm that the uptake (arrows) corresponds to the palatine tonsils. Furthermore, asymmetric uptake in the left tonsil is seen as a mass that bulges into the lumen on the CT scan. The minimal asymmetry of the tonsillar uptake suggests disease; however, definitive diagnosis cannot be made on the basis of PET-CT findings alone. Subsequent biopsy revealed Burkitt lymphoma of the tonsils.