Page 296 - Essential Haematology

282 / Chapter 21 Multiple myeloma and related disorders

The associated paraprotein disappears following cells in the marrow is normal ( < 4%) or only slightly

radiotherapy to the primary lesion. raised ( < 10%) (Table 21.4 ). The concentration of
monoclonal immunoglobulin in serum is less than

30 g/L and other serum immunoglobulins are not
Plasma c ell l eukaemia
depressed. Th e κ or λ light chain is increased in
This rare disease is characterized by a high number serum in one - third of patients; the greater the imbal-

of circulating malignant plasma cells. Th e clinical ance, the more the risk of transformation. No treat-
features tend to be a combination of those found in ment is needed but patients with MGUS develop
acute leukaemia (pancytopenia and organomegaly) overt myeloma or lymphoma at a rate of approxi-
with features of myeloma (hypercalcaemia, renal mately 1% each year and so are usually followed up

involvement and bone disease). Treatment is with regularly in the outpatient clinic. The survival of
supportive care and systemic chemotherapy but patients with MGUS is reduced compared with
prognosis is poor. control populations and this effect increases with

duration of follow - up and age (Fig. 21.9 ).

Heavy - c hain d isease
Amyloidosis

These are now classified with non - Hodgkin lym-
phoma (see p. 267) . The amyloidoses are a heterogeneous group of dis-

orders characterized by the extracellular deposition

Monoclonal g ammopathy of of protein in an abnormal fibrillar form (Table
u ndetermined s ignifi cance 21.5 ). Amyloidosis may be hereditary or acquired
and deposits may be focal, localized or systemic in
Transient or persistent paraproteins can occur in distribution. Th e amyloid is made from diff erent
many other conditions as well as in multiple amyloid fi bril precursor proteins in each type of
myeloma (Table 21.1 ). A serum paraprotein may be disease. Except for intracerebral amyloid plaques, all
sometimes be detected without any evidence of amyloid deposits contain a non - fi brillary glycopro-
myeloma or other underlying disease and is termed tein amyloid P which is derived from a normal
monoclonal gammopathy of undetermined sig- serum precursor structurally related to C - reactive
nifi cance (MGUS) . It is increasingly common with protein (CRP). Th e classic diagnostic histological
age, being present in 1% of persons older than 50 test is red – green birefringence after staining with

years and 3% of those over 70 years. There are no Congo red and viewing under polarized light
clinical complications and the proportion of plasma (Fig. 21.10 ).
Table 21.4 Features of benign and malignant paraproteinaemia.

Benign Malignant
Bence - Jones proteinuria Absent May be present

Serum paraprotein concentration Usually < 30 g/L and stationary Usually > 30 g/L and rising
Serum free light chain ratio Normal Abnormal
Immuneparesis Absent Present
(hypogammaglobulinaemia)
Underlying lymphoproliferative disease or Absent Present
myeloma
Bone lesions Absent Present
Plasma cells in marrow < 10% > 10%