Usefulness of FDG-PET to diagnose intravascular lymphomatosis presenting as fever of unknown origin

Intravascular lymphomatosis (IVL) is a rare systemic disease characterized by proliferation of lymphoid cells within the lumina of small arteries, veins, and capillaries. Diagnosis requires skin, liver, lung, bone marrow, renal, meningeal, or brain vessel biopsy but is often made only when the illness has progressed or post mortem because early involvement of organs was not evident. We report a case of IVL presenting as fever of unknown origin (FUO). In this case, gallium scintigraphy and computed tomography (CT) showed no evidence of malignancy, whereas (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) showed increased FDG uptake in the sternum, left and right vertebra, humerus, femur, and especially ilium. The diagnosis was made on iliac bone marrow biopsy examination. FDG-PET was useful for the detection of spread of disease in a patient with IVL suffering from FUO.