A case of adult onset Still's disease showing marked accumulation in the liver and spleen, on positron emission tomography-CT images.

A 35-year-old woman was admitted to our hospital because of high fever and skin rash, and subsequently diagnosed as having adult onset Still's disease (AOSD). Because of resistance to the steroid hormones, high levels of the serum-soluble form of the interleukin-2 receptor and splenomegaly, we suspected a possible diagnosis of malignant lymphoma and performed positron emission tomography (PET), which disclosed an intense accumulation of 2-deoxy-2 [F18] fluoro-D-glucose (FDG) in the liver and spleen. However, bone marrow aspiration and liver biopsy did not reveal any malignant cells. After the treatment of high-dose adrenocorticosteroids and plasma exchange, her symptoms and laboratory data, including PET findings, gradually improved. This is a rare case of severe AOSD in which an intense accumulation of FDG was detected by PET, and a differential diagnosis from malignant lymphoma may be difficult by FDG-PET alone, so that careful evaluation by techniques including histopathological examination may be necessary.