A 74-year-old female noticed a swelling on her anterior chest wall for several months, gradually increasing in size. More recently it became painful and prompted her to see her General Practitioner. She has no other symptoms.
Which investigations should be performed to exclude myeloma?
What treatment options are most appropriate?
How likely is it that she will progress to myeloma?
Solitary plasmacytomas are relatively rare and represent only 5% of patients with plasma cell dyscrasias. They present either in the bone or as an extramedullary mass. Some will present with a painful/symptomatic lesion (Figure 36.1) whilst others will be picked up during radiological examination for either an unrelated disease or during the investigation of a monoclonal immunoglobulin.1 Solitary bone plasmacytomas (SBP) have a high risk of progression to multiple myeloma and, with the introduction of magnetic resonance imaging (MRI), it is apparent that up to 25% of patients originally labelled as having SBP will in fact have disease elsewhere.2 Extramedullary plasmacytomas (EP) are, in contrast, almost always localized and have a high cure rate with radiotherapy. The median age of presentation with plasmacytoma is in the mid-fifth decade, a little younger than multiple myeloma, and there is a male predominance.3
Extramedullary plasmacytoma in the subdermal plane of the anterior thorax.
Histological diagnosis should include identification of monoclonal plasma cells with appropriate immunohistochemical staining, such as staining for CD138 and κ/λ proteins to demonstrate monoclonal plasma cells. Other useful markers usually employed are MUM1/IRF4, CD56, CD117, CD27 and cyclin D1. To confidently diagnose a SBP there must be a single lytic lesion on skeletal survey and no evidence of systemic myeloma or related end-organ tissue damage (myeloma-related organ and/or tissue impairment; ROTI). Traditionally there should also be no evidence of plasma cell infiltrate in the bone marrow; however, more sensitive techniques are now demonstrating very low-level infiltrates present in a proportion of cases. All patients should be fully assessed to exclude multiple myeloma.4 Solitary bone plasmacytomas primarily affect the axial skeleton and vertebrae.
The role of sensitive imaging techniques is becoming apparent and MRI, computed tomography or positron emission tomography imaging (Figure 36.2) to detect occult lesions not shown on plain radiography is certainly desirable and should be performed wherever possible.5
Positron emission tomography image of a patient with multiple plasmacytomas. Sites of disease activity are indicated by arrows.
The monoclonal serum component is variable in patients with SBP but can be detected in up to 72% of cases. In EP, the quoted incidence is much lower at less than 25%. The levels of serum monoclonal immunoglobulins ...