Active Bone Marrow With Focal FDG Accumulation Mimicking Bone Metastasis With a Case of Early Esophageal Cancer.

A 68-year-old man underwent F-FDG PET/CT for the staging of esophageal carcinoma discovered by a medical checkup. Increased focal accumulation in some vertebrae, right humerus, and right femoral bone was noted on FDG-PET, whereas CT showed relatively high attenuation, and MRI showed hypointense lesions on T1- and T2-weighted imaging. A bone biopsy revealed mildly hypercellular bone marrow in the thoracic spine with FDG accumulation and markedly hypocellular bone marrow in the pelvic bone without an increased uptake. InCl scintigraphy showed a similar distribution and confirmed the diagnosis of bone marrow reconversion.