Canterbury DHB

Laboratory and Radiological Findings

There is usually a normocytic anaemia, often with both neutropenia and thrombocytopenia. ESR/CRP is raised, although both are likely to be normal in light chain and non-secretory myelomas.

Bone marrow aspirate shows an increase in plasma cells, > 10% or > 30% (see diagnostic criteria). Bone marrow trephine may show areas of plasma cell replacement when the aspirate is non-diagnostic, reflecting the focal nature of marrow involvement, at least in the early stages. The current BCSH guidelines emphasise the importance of the trephine and of immunohistochemistry when assessing the extent of myelomatous infiltrate – “Plasma cell phenotyping by flow cytometry &/or immunohistochemistry on trephine biopsy sections is recommended in all cases” (Bird et al, 2014).

Cytogenetic abnormalities are found in 20 to 30 percent of patients using conventional karyotyping. If FISH is used, abnormalities are much more common.

Certain cytogenetic and molecular genetic abnormalities can predict outcome in myeloma. The following are demonstrable using FISH and confer a poor prognosis: t(4;14), t(14;16), t(14;20), del17p and +1q. Chromosome 13 deletions are not actually an independent prognostic marker, but are closely associated with other high risk abnormalities such as t(4;14) so are seen in poor risk disease. The European Myeloma Network recommend FISH testing specifically for t(4;14), t(14;16) and 17p13 deletions, although there is no current evidence to suggest that therapy should be altered based on cytogenetic results. The expense of these tests is often difficult to justify when other routine prognostic tools are available.

Cytogenetics may be required for some trials in myeloma but the current consensus is that conventional karyotyping is of little value.

The biochemical findings are extremely variable. There is often some degree of renal impairment and occasionally patients present in acute renal failure. Hypercalcaemia often occurs at some stage in the disease.

A monoclonal protein will be present in all but non-secretory myeloma. Normal immunoglobulin levels are often reduced. The concentration of the monoclonal protein is important in distinguishing myeloma from MGUS. The concentration of all these proteins are one of a number of factors that form the basis for two of the systems that describe criteria for establishing a diagnosis of myeloma - see the WHO Criteria for Myeloma Diagnosis (WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues 2008, 4th Edition, p202).

Radiologically, there may be lytic bone lesions anywhere in the skeleton, although these are usually found centrally. MRI may show focal bone marrow abnormalities and is the investigation of choice for suspected root or spinal cord compression.

Topic Code: 6470