Diffuse bone marrow uptake on whole-body F-18 fluorodeoxyglucose positron emission tomography in a patient taking recombinant erythropoietin

F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) is used extensively in oncology to diagnose, stage, and restage patients with various malignancies. Many patients treated for malignancies develop neutropenia secondary to marrow suppressive chemotherapy and are subsequently treated with synthetic hematopoietic growth factors (HGF), both granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte-colony-stimulating factor (G-CSF). Patients taking HGF can present a diagnostic challenge for those interpreting PET because they can demonstrate diffuse marrow uptake on FDG-PET scans, mimicking diffuse bone marrow metastases. It has not been reported whether bone marrow uptake is affected on PET scans in patients taking erythropoietin, the erythroid-specific cell-line stimulator. We report a case of extensive diffuse bone marrow uptake in a 77-year-old man with a history of colon cancer who began taking erythropoietin 3 weeks before his PET scan. This case demonstrates the need to consider erythropoietin in the differential diagnosis of possible etiologies causing diffuse bone marrow uptake on PET scans.