Blood L6: Plasma Cell Diseases Quiz

Blood L6: Plasma Cell Diseases

• Plasma cell maturation to antibody-secreting cells is triggered by antigens.
• Monoclonal neoplasms arise from B lymphocytes.
• Clinical manifestations involve neoplastic cell expansion, secretion of cell products (immunoglobulins/lymphokines), and host response.
• Classification includes:
  • Monoclonal gammopathy of undetermined significance (MGUS)
  • Multiple myeloma
  • Plasma cytoma
  • Immunoglobulin deposition diseases (primary amyloidosis, AL protein, systemic light/heavy chain diseases)
  • Osteosclerotic myeloma (POEMS)
• Multiple myeloma features include polyneuropathy, organomegaly, endocrinopathy, and skin changes.
• Alkaline phosphatase (ALP) is high in metastatic carcinoma but normal in multiple myeloma (MM).

Multiple Myeloma

• Malignant proliferation of plasma cells from a single clone.
• Common in those aged 60+.
• Common symptoms include bone pain (affecting 70% of patients, often in back/ribs, worsened by movement), osteoporosis, pathological fractures, and lytic bone lesions.
• Renal failure affects ~25% of patients, with abnormal renal pathology seen in over half.
• Pathogenesis includes hypercalcemia, light-chain deposition, amyloidosis, urate nephropathy, drug toxicity (NSAID, bisphosphonates), and contrast dye-related renal dysfunction (light-chain cast nephropathy/amyloidosis).
• Anemia (normocytic and normochromic) affects ~80% of patients. Pathogenesis includes bone marrow infiltration, inhibitory factor production, hemolysis, and decreased erythropoietin levels.
• Hypercalcemia, renal affection, and anemia are key symptoms.

Other Factors and Investigations

• Recurrent infections are common, with Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli being frequent pathogens.
• Hyperviscosity, cryoglobulinemia, amyloid deposits, hypercalcemia, nerve compression, anti-neuronal antibodies, POEMS syndrome, and therapy-related toxicity may be associated.
• Hepatosplenomegaly and lymphadenopathy are uncommon.
• Hyperviscosity syndrome is found in ~2% of cases.
• Investigations such as complete blood count (CBC), erythrocyte sedimentation rate (ESR), blood chemistry (raised serum calcium, urea nitrogen, creatinine, uric acid; usually normal alkaline phosphatase despite bone involvement), and serum B2-microglobulin quantification are crucial. A B2-microglobulin level below 3.5 mg/L indicates a good prognosis, while above 5.5 mg/L suggests a poor prognosis.
• Protein electrophoresis, 24-hour urine protein excretion, and bone marrow analysis are vital diagnostic tools to measure free light chains and characterize the M component. (e.g., Bence Jones protein in urine).
• A significant finding is monoclonal plasma cells (CD138+) in bone marrow.
• Radiological investigations (chest/bone X-rays) may reveal lytic lesions/diffuse osteopenia, light chains >10mg/day in urine (Bence Jones protein).

Treatment

• Supportive Treatment:
  • Hypercalcemia management: Bisphosphonates, glucocorticoids, hydration, natriuresis.
  • Renal disorders: High fluid intake to prevent dehydration and help excrete light chains/calcium.
  • Plasmapheresis (treating hyperviscosity).
  • Pain control.
  • Anemia treatment.
• Specific Treatment:
  • Allogenic stem cell transplantation (patients under 50 with no comorbidities).
  • Autologous stem cell transplantation (after aggressive chemotherapy to reduce tumor numbers).
  • Chemotherapy.