B cell malignancy – abnormal production of monoclonal immunoglobulin

Subtypes

1. Multiple
2. Solitary
3. Extramedullary

Clinical

• Increased malignant plasma cells – replace bone marrow and erode bone, therefore pancytopenia
• Develop in vertebrae, ribs, pelvis, skull
• Localized pain
• Pain aggravated by exercise, relieved by rest
• Mandible – Paresthesia of lip, loose teeth
• Swelling
• Numbness
• Weightloss
• Weakness
• Anemia
• Bleeding
• Infection
• Amyloidosis (10%) – amyloid deposition reason for macroglossia
• Osteoporosis and pathological fractures

Radiology

• Sharply punched out, non corticated radiolucencies

Diagnosis

• Full blood screen:
  • Anemia
  • Rouleaux formation
• IgA and IgG proteins in serum (electrophoresis)
• Bence-Jones proteinuria (in urine)
• PBF – Plasma cells
• Stains for amyloid – Congo red, thioflavin T
• Immunochemistry for λ light chain
• Bone marrow biopsy

NB: Amyloidosis also seen in osteomyelitis and CEOT

Histology

• Monotonous proliferation of neoplastic plasma cells
• Peripheralization of chromatin – clock face appearance Picture

Differential diagnosis

• Langerhans cell histiocytosis
• Lymphoma
• Metastases

Management

• Combination chemotherapy
• Poor prognosis

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