Increased renal corticomedullary FDG activity in a patient of NHL-malignant or benign?

Authors describe diagnostic dilemma of differentiating pyelonephritis with lymphomatous involvement of kidney in a known case of lymphoma. FDG uptake pattern was non-discriminatory and pyelonephritis diagnosed retrospectively on follow up study. Authors emphasize the importance of recognition of features and subtle clues of infection evident on CT component of PET-CT.