Myeloma

Multiple myeloma (MM) (myeloma) is a clonal B-cell disorder characterized by uncontrolled proliferation of plasma cells secreting immunoglobulins or light chains which can be detected in urine, serum or both [1]. Very rarely, the plasma cells may be nonsecretory. Plasma cells are mainly centred in the bone marrow but can also accumulate to form localized soft tissue or bone plasmacytomas. These can result in fractures or cause local compressive symptoms.

Myeloma accounts for approximately 1% of all cancers and 10% of haematological cancers. The annual incidence in the UK is approximately 4–5 per 100,000. Myeloma occurs in all races though the incidence is higher in Africans and African Americans. It is slightly more common in men. Myeloma is a disease of older adults. The median age at diagnosis is 66 years, and only 10% and 2% of patients are younger than 50 and 40 years, respectively.

In some studies, over 10% of myeloma patients required intensive care support for indications such as sepsis, acute renal failure and metabolic complications. Hospital mortality appears to be falling with time for myeloma patients admitted to intensive care, and admission to intensive care earlier after hospital admission has also been associated with lower mortality [2].

Clinical features and presentation:

• May vary from asymptomatic disease to increased tiredness, fatigue, bony pain and pathological fractures.
  
• Spinal cord compression.
  
• Symptoms of bone marrow infiltration causing anaemia, thrombocytopenia and recurrent infections because of low white cell count.
  
• Recurrent infections due to immune paresis.
  
• Renal failure secondary to cast nephropathy (myeloma kidney), amyloidosis, drugs, radiological contrasts, hypercalcaemia, etc.
  
• Hypercalcaemia causing confusion, pain and constipation.
  
• Hyperviscosity syndrome (HVS).
  
• Peripheral neuropathy is uncommon in myeloma at the time of initial diagnosis and, when present, is usually due to amyloidosis. An exception to this general rule occurs in the infrequent subset of patients with POEMS syndrome (osteosclerotic myeloma) in which neuropathy occurs in almost all patients.
  
• CNS involvement – Spinal cord compression from plasmacytomas is common, but leptomeningeal involvement is rare. When the latter is present, the prognosis is poor with survival measured in months. Rare cases of encephalopathy due to hyperviscosity or high blood levels of ammonia, in the absence of liver involvement, have been reported.

All myeloma cases have a prophase where a paraprotein can be found in the blood but without other features of myeloma. These plasma cell dyscrasias are monoclonal gammopathy of uncertain significance (MGUS) and the more advanced smouldering myeloma. Diagnostic criteria are explained in the following text [3].