Diffuse FAPI-46 Uptake in Bone Marrow: A Case of Primary Myelofibrosis With Superscan Pattern on Bone Scintigraphy

We present the case of a 65-year-old woman with a history of bone pain, who was evaluated for worsening symptoms, including malaise, weight loss, and night sweats. Initial assessments revealed anemia and elevated lactate dehydrogenase, ESR, and CRP levels. Imaging studies showed splenomegaly and diffuse lytic/sclerotic changes in the skeleton. A whole-body 99m Tc-MDP scan indicated markedly increased skeletal uptake, consistent with a superscan pattern. Subsequent 99m Tc-FAPI-46 scanning revealed diffuse skeletal uptake along with focal splenic uptake. Bone marrow biopsy confirmed primary myelofibrosis. This case underscores the utility of imaging modalities in diagnosing primary myelofibrosis, disease status evaluation, and differentiating it from other conditions.