Multiple myeloma is characterized by all except:
|A||Presence of light chains|
|D||Hyper gamma globulinemia|
Plasma Cell Dyscrasias
These are a group of disorders characterized by the expansion of a single clone of immunoglobulin (Ig) secreting cells and are associated with increase in levels of homogenous Ig or its fragments.
Examples of Monoclonal Gammopathies
1. Myeloma - a. Multiple myeloma b. solitary plasma cytoma
2. Waldenström’s macroglobulinemia
3. Heavy chain disease (γ, α, μ)
a. Gamma Chain (Franklin disease) – Seen in elderly resemble lymphoma.
b. Franklin disease is a gamma heavy chain disease. It characterized by elevated levels of a gamma heavy chain of immunoglobulins in blood and urine.
c. Alpha chain (Seligmann’s disease) - It is the most common type of heavy chain disease.
d. mu chain – Rarest form, seen in patients with CLL.
4. Primary or immunocyte associated amyloidosis
5. Monoclonal gammopathy of undetermined significance (benign IgG, IgA, IgD, IgM, and rarely free light chains, biclonal gammopathies, idiopathic Bence Jones proteinuria)
It is a malignant neoplasm of plasma cells.
Peak age group: 60 years and above
Light chain disease: No serum M component; only Bence Jones proteinuria
Immunopathology: In myeloma, the transformation of B – lymphocytes to plasma cells manufacturing immunoglobulins is defective resulting in the production of abnormal monoclonal immunoglobulin. Q
Variant Forms of Myeloma (Ref, H-18th Edi, Pg.- 936)
1. Smouldering myeloma (SMM M – protein level > 3 gm/dl in the serum, > 10% atypical plasma cells in the bone marrow but no anemia, renal insufficiency or skeletal lesions). No lytic lesion, Serum Calcium is normal.
2. Plasma cell leukemia (> 20% plasma cells in the peripheral blood and absolute plasma cell count is around 2000/mL).
3. Nonsecretory myeloma – All features of MM except there is no M protein in serum or in urine.
4. IgD myeloma (M – protein is smaller, and Bence – Jones proteinuria is of gamma type. Extramedullary plasmacytomas, plasma cell leukemia, and amyloidosis are common). They present with small band or no evident M-spike on serum protein electrophoresis. Higher incidence of renal insufficiency, amyloidosis and proteinuria than IgG / IgA myeloma. Higher incidence of extramedullary involvement and inferior survival rates.
5. Osteosclerotic myeloma (associated with the acronym POEMS – Polyneuropathy, Organomegaly, Endocrinopathy, M – protein, Skin changes)
6. Solitary plasmacytoma