Multiple Myeloma

Definition

  • primary malignant tumour caused by malignant proliferation of plasma cells
  • Also known as Kahler’s disease

<>Incidence

  • Most common primary malignant tumour of bone
  • 27-44% of biopsied bone tumours
  • 1% of all malignant disease
  • Average age is 60
  • Rare in patients less than 40 years old
  • M>F by 2:1

L>Localization

  • Spine is commonest, particularly lower thoracic & lumbar areas
  • Marrow rich flat bones of pelvis, skull, ribs, clavicle & scapula are frequently involved
  • In long bones femur & humerus are much more commonly affected than distal appendicular skeleton

P>Pathology

G>Gross

  • Multiple permeative lesions which are filled by gelatinous, red, soft masses of neoplastic plasma cells, “current jelly” in appearance lesion is usually multicentric

Micro>Microscopic

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  • Sheets of closely packed cells with basophilic cytoplasm cells are usually uniform
  • few mitotic figures nuclei have clock face appearance
  • surrounding cytoplasm has perinuclear clear zone or halo (which is taken up by Golgi apparatus)
  • Occasionally only amyloid may be seen in specimens

    • Immun>Immunohistochemistry

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  • CD56, natural killer antigen, is frequently seen on myeloma cells but not reactive plasma cells

    • Signs>Signs & symptoms

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  • Pain
    • cardinal initial symptom
    • Initially intermittent & becomes continuous
    • acute sudden exacerbation may represent pathological fracture
  • Paraplegia may occur with vertebral collapse

    • Other presentations:

    • Anaemia
    • Infection
    • Renal failure
    • Hypercalcaemia
    • Weight loss
    • Amyloidosis
    • Neurological findings
    • Peripheral polyneuropathy

    Inves>Investigations

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  • FBC
    • Anaemia – often normochromic normocytic
    • Thrombocytopaenia
  • ESR
    • elevated
  • Electrolytes
    • Hypercalcaemia in 20-50% of patients
    • Normal phosphate
    • Hyperuricaemia
  • Serum proteins
    • Hyperglobulinaemia with reversal of albumin-globulin ratio
  • Beta –2 microglobulin
    • elevation is poor prognostic finding
  • Urine
    • Bence Jones proteins
  • Bone marrow aspiration
    • diagnostic

    • Xray

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  • Diffuse osteoporosis
    • first sign of myeloma
    • Usually most evident within spine
    • Goes on to result in pathologic vertebral collapse, which may cause vertebra plana or so called wrinkled vertebra
  • Osteolytic defects
    • Punched out, sharply circumscribed
    • No surrounding sclerosis
    • Most frequently seen in bones with haematopoietic potential
      • ie skull, pelvis, long bones, clavicles & ribs
      • In long bones diaphysis is most often involved
      • In vertebra pedicles are often preserved
    • In skull this is referred to as raindrop skull
      • Myelomatous deposits in skull are relatively uniform in size If lesions vary lot in size they are more likely to be secondaries
    • ribs may have “ballooned out” appearance
  • Sclerotic lesions
    • Less than 3% of patients have sclerosis on their X-rays
    • Can have solitary ivory vertebra
    • sclerotic form of disease is associated with peripheral demyelinating symmetrical polyneuropathy
    • With sclerotic lesions differential diagnosis includes:
      • Osteoblastic metastasis
      • Mastocytosis
      • Lymphoma
      • Myelosclerosis

    • Bone Scan

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  • Bone scans are cold except at site of pathological fractures
  • This is because of deficiency of osteoblastic activity at site of lesion

    • Differential >Differential diagnosis

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  • Metastatic carcinoma
  • Lymphoma
  • Hyperparathyroidism

    • Treatment

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  • Supportive treatment
    • including rehydration & management of hypercalcaemia may be necessary before definitive treatment
  • Radiotherapy
    • treatment of choice for localized disease, after excisional biopsy if possible
  • Chemotherapy
  • Prophylactic long bone fixation, or tumour prosthesis if required around joints

    • Prognosis

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  • 90% dead within 3 years
  • Most deaths are due to renal failure

    • Plasm>Plasmacytoma (solitary myeloma)

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  • This is forerunner of disseminated myeloma
  • Commonest site is vertebral column
  • overall survival rate was 74% at 5 years & 45% at 10 years
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