18F-FDG PET/CT in the evaluation of solitary extramedullary plasmacytoma

The role of 18F-FDG PET/CT in patients with multiple myeloma (MM) and other plasma cell disorder is well known. Solitary plasmacytoma (SP), an extremely rare form within this entity that accounts for approximately 4% of plasma cell malignancies, can be classified as solitary bone plasmacytoma (SBP) or solitary extramedullary plasmacytoma (SEMP). EMP (extramedullary plasmacytoma) is a rare neoplasm characterized by the monoclonal proliferation of plasma cells outside the bone marrow. Breast and craniocerebral region are the uncommon sites of presentations of EMP and rarely reported in the literature. The most frequent site of presentation is upper airways. EMPs have similar pathogenesis as MM, however, they differ in management as they are radiosensitive in nature, and radiotherapy is the preferred treatment modality. As solitary EMP has a better prognosis than SPB with a lower conversion rate to MM, accurate staging is essential to plan the treatment. 18F-FDG PET/CT has higher sensitivity for treatment response evaluation. In the present case series, it is aimed to depict the role of 18F-FDG PET/CT in newly diagnosed solitary EMP with different sites of origin to exclude further lesions which lead to change in a treatment plan and in treatment response assessment.