Diffuse FDG uptake of bilateral renal cortex in intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of large B-cell lymphoma characterized by selective growth in the lumina of small vessels in systemic organs. Renal involvement in IVLBCL is rarely reported. Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is a powerful tool for the diagnosis of lymphoma, but physiologic FDG excretion in the kidneys makes the interpretation of the tracer uptake in this organ difficult. We treated a 71-year-old Japanese woman with infarct-like lesions whose lactate dehydrogenase was elevated; IVLBCL was thus suspected. FDG-PET/CT revealed diffuse FDG uptake of the bilateral renal cortex, but the patient's creatinine clearance was normal and proteinuria was undetectable by a qualitative urinalysis. The patient was diagnosed with IVLBCL based on a random skin biopsy. When IVLBCL is suspected, it is necessary to be careful about the renal cortex FDG uptake in order to avoid missing renal lesions.