The location of the solitary plasmacytoma is crucial to predicting its natural history. The majority of patients with extra-osseous (non-bone-involving) plasmacytoma have localized disease which is potentially curable with irradiation. The majority of patients with solitary plasmacytoma of bone will eventually manifest overt multiple myeloma.

3.1 Diagnosis

All these criteria must be present:

• Biopsy proof of a plasma cell tumour
• No lytic bone lesions except the tumour itself
• Bone marrow plasma cell proportion less than 10%
• For solitary plasmacytoma of bone: no significant PET scan abnormality at another site

A serum and/or urine monoclonal paraprotein may be present. Usually the uninvolved immunoglobulin levels are normal.

3.2 Staging

No standard system is available. Patients should undergo all the usual tests for multiple myeloma. CT scan of the plasmacytoma should be obtained prior to radiation therapy.

3.3 Treatment

Standard treatment for solitary plasmacytoma is irradiation to the entire lesion with appropriate margins.

3.4 Follow-up

Solitary extra-osseous plasmacytoma