This case illustrates a discrepancy between the revised Lugano Classification (PD) and the immune-related response criteria (PR) given the fact that the immune-related response criteria do not take into consideration PET/CT findings. This type of discrepancy is particularly notable in cases with bone marrow involvement. Oftentimes, lymphomatous involvement of the bone marrow is either not measurable (due to absence of soft tissue component) or imperceptible on CT. Therefore, these findings cannot be integrated in the tumor burden of the immune-related response criteria. Restaging PET-CT is at 12 weeks. Restaging PET/CT 2 at 20 weeks demonstrates new areas of FDG uptake in the left side of T9 vertebral body (arrows) and increasing uptake in the left acetabulum, suggesting increasing extent of marrow disease, whereas this is barely seen on CT. Marked physiologic uptake is also seen in brown fat (asterisks).