A 64-year-old man was admitted for evaluation of recently developed anemia and bone pain. The bone scan showed diffusely active lesions in the peripheral bones, symmetrically. Interestingly, 18F-FDG PET/CT revealed the hypermetabolic changes in the peripheral bones as well as the internal organs. Biopsy of bone marrow confirmed the diagnosis of intravascular B-cell lymphoma. After the 3 cycles of R-CHOP chemotherapy, 18F-FDG PET/CT showed improvement of the previous hypermetabolic lesions, suggesting good response. Intravascular B-cell lymphoma is a rare and aggressive variant of diffuse large cell lymphoma characterized by proliferation of malignant cells within the vascular lumina.