Definition

Incidence

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

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

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

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

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

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

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

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