A 8-year-old girl was admitted evaluation of massive hepatosplenomegaly. Laboratory findings showed anemia ( Hb = 112; N 115-155 g/L) and thrombocytopenia ( Platelets = 61 ; N 140-440 10^9/L). C Reactive protein was normal at 0.9. A F18-FDG PET/CT was requested to rule out leukemia/lymphoma.
Mildly hypermetabolic massive splenomegaly with some degree of hepatomegaly. There is bone marrow expansion without focal bony lesions. The absence of significant lymph nodes activity, focal uptake in the liver, spleen and bone made the diagnosis of malignancy less likely.
Bone marrow biopsy showed spumous histiocytes with some eccentric nuclei. Assay of lysosomal enzymes in the leukocytes demonstrated a reduced activity of ß-Glucosidase enzyme: 3.7 nmol/h/mg of protein (normal control 10.6). Diagnosis was made of Gaucher disease [1,2].
Diverse nuclear medicine procedures have been used to assess Gaucher disease: Tc99-MDP for bone infarcts and Tc99m-sulfur colloid for the evaluation of the reticuloendothelial system following enzyme replacement therapy showing reduction of bone marrow expansion and lung uptake [3,4]. Tc99m-MIBI have been shown to accumulate in the glucosidase laden macrophages, demonstrating a more specific distribution of the disease than Tc99-sulfur colloid . More recently, F18-FDG PET/CT has been proposed as an alternative to Tc99m-MIBI to monitor bone marrow disease. As proposed for Tc99m-Sestamibi, F18-FDG uptake is likely due to direct accumulation in Gaucher cells . Focal infiltration of the spleen by Gaucher has also been reported with F18-FDG  . More recently, direct labelling of ß-Glucosidase with F18 has been performed and studied in a murine model . The exact role of PET/CT in Gaucher disease remains to be clarified.
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