Plasma Cell Disorders (Dyscrasias)

Question 1

What is multiple myeloma?

Answer 1

Malignant proliferation of plasma cells in bone marrow

Question 2

What is the most common primary malignancy of bone? Malignant lesion overall?

Answer 2

Multiple myeloma; Metastatic cancer

Question 3

Clinical features of multiple myeloma

Answer 3

Bone pain w/ hypercalcemia (Plasma cells -> activate RANK on osteoclasts -> bone destruction -> Lytic punched-out lesions in vertebrae and skull -> increased risk of fracture); Elevated serum protein due to overproduction of Ig; M spike present on serum protein electrophoresis (SPEP) due to monoclonal IgA/G, Increased risk of infection due to dominance of monoclonal Ab, Rouleaux formation on blood smears due to proteinemia, Primary light chain amyloidosis due to free light chains circulating in serum; Proteinuria - free light chains excreted as Bence Jones protein

Question 4

What is Monoclonal Gammopathy of Undetermined Significance (MGUS)? Population?

Answer 4

Increased serum protein with M spike on SPEP but features such as lytic bone lesions/hypercalcemia/AL amyloid/Ben Jones proteins are absent; Elderly

Question 5

What is Waldenstroem Macroglobulinemia? Clinical features? Tx

Answer 5

B-cell lymphoma with monoclonal IgM production; Generalized LAD W/O bone lesions, Increased serum protein with M spike (mostly IgM), Visual and neurological deficits due to increased serum viscosity due to IgM, bleeding due to high viscosity which disallows effective platelet aggregation; Plasmapheresis which removes IgM