Page 358 - Concise Pathology for Exam Preparation ( PDFDrive )

12 Haematology 343

• Splenic histology reveals mononuclear cell infiltration of red pulp and engorgement of
sinuses.

Q. Enumerate various plasma cell disorders.
Ans. Plasma cell disorders are monoclonal neoplasms developing from common progeni-
tors in the B-lymphocyte lineage. Also called paraproteinaemias and plasma cell dyscrasias,
these include the following diseases:
• Multiple myeloma
• Waldenstrom macroglobulinaemia
• Primary amyloidosis
• Heavy chain disease

Q. Write in detail on the pathology, clinical features and laboratory
diagnosis of multiple myeloma.

Ans. Clonal proliferation of plasma cells induced by the cytokine IL6, which is secreted
by fibroblasts and macrophages in the bone marrow stroma.
• Plasma cells produce excessive immunoglobulins with only one type of light chain
(kappa or lambda). These excess light chains are low molecular weight and appear in
the urine as Bence Jones proteinuria.
• The immunoglobulin produced is called a ‘paraprotein’ (M-protein). It appears on
electrophoresis as a clear-cut band (M-band or M-component).
• The most common M component is IgG (60%), followed by IgA (20–25%); only rarely
is it IgM, IgD or IgE. In the remaining cases, the plasma cells produce kappa or lambda
light chains only.

Clinical Features
• Peak incidence is between 60 and 70 years and males are more affected than females.
• Solitary bone plasmacytomas: Single lytic bone lesion without marrow plasmacytosis;
present as punched-out lesions involving the flat bones (vertebrae, skull, sternum, ribs
and clavicle). Manifest with bone pain, pathological fractures and compressive my-
elopathy (due to vertebral collapse and compression).
• Extramedullary plasmacytoma: Lesions in soft tissue (mainly in upper respiratory tract)
without marrow plasmacytosis
• Those with skeletal plasmacytomas develop full-blown multiple myeloma over a period
of 5–10 years; whereas, extraosseous plasmacytomas spread less commonly and are
often cured by local resection.
• Serum uric acid is elevated due to increased cell turnover.
• Osteoclasts are stimulated resulting in bone resorption and generalized osteoporosis.
• Mobilization of calcium from bone results in hypercalcaemia, hypercalciuria and neph-
rocalcinosis.
• Renal involvement: Bence Jones proteinuria, amyloidosis, hypercalcaemia and hyper-
uricaemia result in renal damage and renal failure.
• Immune system involvement: Increased susceptibility to infections, particularly of the
respiratory system and urinary tract.
• Hyperviscosity syndrome: Results from increased viscosity of blood. May cause blurred
vision with retinal venous congestion, papilloedema, headache, vertigo, nystagmus,
postural hypotension, congestive cardiac failure and clotting problems (purpura, epi-
staxis and gastrointestinal bleeding).
• May present with neurological manifestations (amyloid peripheral neuropathy, carpal
tunnel syndrome, compressive myelopathy and radiculopathy)

Pathology
• Bone marrow is infiltrated heavily with atypical plasma cells. Gradual replacement
of the marrow by plasma cells results in anaemia, leucopenia and thrombocytopenia
(Fig. 12.10).

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