Figure 1. There is an enhancing, hypermetabolic (SUV_max 5.9) soft tissue mass wrapping around and invading the spine of the left scapula.

Figure 2. There is an enhancing, hypermetabolic (SUV_max 6.4) lobulated soft tissue mass in the left supradiaphragmatic region extending to the lower anterior chest wall, displacing the hemidiaphragm posteriorly. The adjacent left 6th rib is sclerotic (bone window not shown). The mass had increased in size compared to previous CT examination (not shown).

Figure 3. There are 2 slightly hypermetabolic soft tissue nodules in the subcutaneous fat of the lower back (SUV_max 2.6 and 0.8).

Figure 4. Cine MIP Further hypermetabolic lesions are seen in the left mandible, bilateral thighs, right thumb, left para-aortic region and back.

A plasma dyscrasia was first identified by Dalrumphe and Bence-Jones in 1846 when they described a condition with diffuse bone pain and marked proteinuria. It was successfully termed a distinct histopathologic entity in 1873. This plasma cell neoplasm has since been classified into one of three categories: the disseminated form, multiple myeloma, and the localized forms of medullary or extramedullary plasmacytomas.

Multiple myeloma is characterized by multifocal skeletal involvement, with the possibility of spread to lymph nodes and extranodal sites such as the skin. The peak age of incidence is 50-60 years. In 99% of patients, there are increased blood immunoglobulins and/or urinary light chains (Bence Jones proteins).

PET/CT is useful in the diagnosis of multiple myeloma by identifying optimal sites for biopsy, for staging and restaging disease, for detecting extramedullary disease, and for monitoring response to therapy. PET/CT is also a reliable technique for detecting occult infection in patients with haematologic malignancies even in the setting of severe immunosuppression, thus optimizing patient management. The modality is more sensitive than skeletal survey in detecting small lytic lesions, but appears less sensitive than MRI in detecting an infiltrative pattern in the spine. Active multiple myeloma has also been imaged with 11(C)-methionine PET/CT, based on increased methionine uptake by plasma cells.