Imaging of systemic mastocytosis by FDG-PET/CT demonstrates increased activity in cortical bone

A patient with systemic mastocytosis underwent a FDG-PET/CT scan. CT demonstrated loss of corticomedullary differentiation in the axial skeleton and thickening of cortical bone in the appendicular skeleton consistent with myelofibrosis and osteosclerosis. Remarkably, the bones of the lower extremities displayed increased uptake of FDG in the cortical bone and marrow space. A diffuse pattern of uptake was also seen in the bones of the axial skeleton instead of the typical pattern of FDG uptake confined to the marrow consistent with the loss of corticomedullary differentiation. We hypothesize that the increased FDG uptake in cortical bone is due to increased osteoblastic activity causing the myelofibrosis.