Role of FDG PET/CT in Diagnostic Evaluation of Granulocytic Sarcomas: A Series of 12 Patients

OBJECTIVE: Granulocytic sarcoma (GS) is a rare extramedullary manifestation in patients with acute myeloid leukemia (AML), which can precede the diagnosis or occur in the posttreatment setting. Unlike its established role in other hematological malignancies like Hodgkin's on non-Hodgkin's disease, the exact role of positron emission tomography/computed tomography (PET/CT) in AML with or without GS remains to be defined. MATERIALS AND METHODS: We retrospectively reviewed PET/CT scans of 12 patients with histologically proven GS. Marrow examination of these patients identified nine patients with isolated GS (without existent leukemia) and three patients with coexistent leukemia. RESULTS: PET/CT accurately identified all clinically evident GS in all 12 patients at initial staging and at follow-up with tumors, showing moderate to high 2-deoxy-2-fluoro-D-glucose uptake. Coexistent marrow disease was seen on PET/CT in three patients, which was confirmed on histopathology. In the same patients, PET/CT also detected additional sites of extramedullary disease in 66.6% (n = 8), which was either clinically occult or not evident on routine CT. CONCLUSION: PET/CT appears to be a highly sensitive imaging modality in diagnostic evaluation of GS. The most important indication of using PET/CT in these cases is to identify additional sites of clinically occult extramedullary disease, which can potentially impact treatment decisions and outcomes.