Splenic accumulation is variable. Focus on the causes, diseases, degrees and patterns

Learning Objectives The objectives of this study are 1. understanding various causes of increased splenic accumulation, 2. presenting various FDG-PET/CT images of splenic diseases, and 3. understanding what factors should be considered while interpreting images by dividing subjects into groups according to the degree and pattern of accumulations.

Increased splenic accumulation results from various factors. Splenic invasion may occur in malignant lymphoma if treatment has not been initiated;moreover, splenic accumulation can be seen in sarcoidosis.Granulocyte colony-stimulating factor (G-CSF) administration may lead to secondary enhancement; therefore, in cases with increased accumulation in both the spleen and bone marrow, the presence of G-CSF administration should be confirmed. Further, increased splenic accumulation can be seen as a post-chemotherapy change and can occur in collagen diseases such as Sjogren’s syndrome and systemic lupus erythematosus. Increased accumulation patterns can be diffuse or nodular, with or without splenomegaly. Varied accumulation patterns are observed in malignant lymphoma. Moreover, both diffuse and nodular accumulation patterns can be observed in sarcoidosis. In case of nodular accumulation patterns, secondary increase is unlikely to result from collagen diseases or G-CSF administration; however, in patients with a history of malignant disease, the possibility of splenic metastasis needs to be considered,along with sarcoidosis and malignant lymphoma. Nonetheless, imaging tests alone are often insufficient to achieve a definitive diagnosis, and in such cases, splenectomy, which aids in both diagnosis and treatment, must be performed. The present study presents FDG-PET/CT images of the spleen in following cases: malignant lymphoma, sarcoidosis, following chemotherapy, hypersplenism associated with cirrhosis, following G-CSF administration, collagen diseases, enhanced accumulation in leukemia, splenic metastasis, hemangioma, and accessory spleen.