Solitary plasmacytoma of bone SPB

Diagnostic criteria

• Generally no paraprotein in serum or urine though small band may be present.

• Single area of bone destruction due to clonal plasma cells.

• BM not consistent with MM.

• Otherwise normal skeletal survey (and MRI of spine and pelvis).

• No myeloma-related organ or tissue impairment (end-organ damage).

2g2 • Represents ~5% plasma cell neoplasia: 9: 3 ratio 2:1; median age 55.

• Lesion usually in axial skeleton; 66% in spine.

• Generally presents with bony pain; may cause cord/root compression.

• Diagnosis requires biopsy or FNA, exclusion of MM (p273) and exclusion of other bone lesions with MRI (FDG-PET/99Tc-MIBI under examination).

• Serum or urine paraprotein detected in 24-72%; generally low level.

• Adverse prognostic factors for progression to MM include persistence of paraprotein >1 year after radiotherapy, immuneparesis and lesion >5cm.

• Negative MRI of spine is good prognostic feature.

• Treat with fractionated radical radiotherapy 40Gy (50Gy for lesions >5cm); local control 80-95%; curative in 50% if solitary lesion; DFS ~40% at 5 years.

• Treat non-responders with chemotherapy as for myeloma (p278).

• Regular follow-up to monitor paraprotein; disappears in 25-50% (often slowly over several years).

• ~75% progress to MM; treat as de novo MM (p278); high response rate.

• Some patients develop multiple solitary recurrences; treat each with local radiotherapy.

• Median survival ~10 years.

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