Calcium Pyrophosphate Deposition (Pseudogout)

Related Subjects: |Calcium Physiology |Rheumatoid arthritis |Systemic Sclerosis (Scleroderma) |RA vs OA |Acute and Chronic Gout |Calcium Pyrophosphate Deposition (Pseudogout)

💡 Always aspirate the joint if diagnosis is uncertain to rule out septic arthritis 🔴. Send fluid for: cell count + Gram stain (Microbiology), polarizing microscopy for crystals (Histopathology), and culture. Record colour, viscosity, and turbidity of aspirate.

🦴 About

• Pseudogout = calcium pyrophosphate dihydrate (CPPD) crystal deposition disease.
• Described in 1962 by Kohn et al. Common in older adults, but can appear earlier if metabolic associations present.
• Favours large joints: knees, wrists, hips, pubic symphysis.

⚡ Aetiology

• Excess inorganic pyrophosphate → CPPD crystals deposit in articular & periarticular tissues.
• Age-related cartilage degeneration, genetic predisposition, or secondary to metabolic disease.

🔗 Associations

• Haemochromatosis
• Hypothyroidism
• Hyperparathyroidism
• Hypomagnesaemia
• Wilson’s disease
• Bartter syndrome
• Amyloidosis, Ochronosis
• Haemophilia

📸 Imaging: Chondrocalcinosis

🔥 Clinical Features

• Acutely inflamed, hot, red, swollen, tender joint.
• Typically monoarticular (large joints), but can be oligo/polyarticular.
• Subacute or prolonged attacks (weeks–months).
• More common in elderly; in young patients think metabolic causes (e.g. haemochromatosis, Wilson’s).

🧪 Investigations

• Bloods: FBC, ESR/CRP ↑, U&E, calcium (for hyperparathyroidism), ferritin (haemochromatosis).
• Blood cultures: if septic arthritis in differential.
• X-ray: Linear calcification of hyaline or fibrocartilage = chondrocalcinosis.
• Joint aspirate: Rhomboid crystals, positively birefringent 🔬.

📊 Gout vs Pseudogout

💊 Management

• Acute attack:
  • Rule out septic arthritis (aspirate first!).
  • NSAIDs 🔵 (if tolerated, +PPI).
  • Colchicine 0.5 mg BD for several days.
  • Prednisolone 10–15 mg PO short course if NSAIDs/colchicine unsuitable.
  • Admit if septic arthritis suspected.
• Chronic / recurrent disease:
  • Hydroxychloroquine or Methotrexate in persistent inflammatory arthritis.
  • Prophylaxis: low-dose colchicine or NSAID (with PPI).
• No urate-lowering equivalent: Unlike gout, no crystal-reducing therapy exists for CPPD.

📚 References

• Treatment and management of pseudogout: Insights for the clinician
• Patient information leaflet

Cases - Calcium Pyrophosphate Deposition Disease (CPPD / Pseudogout)

• Case 1 - Acute Monoarthritis (Pseudogout Attack) 🦵: A 72-year-old woman presents with sudden painful swelling of her left knee, warm and erythematous, but no trauma. She is afebrile, CRP 48. Joint aspiration: turbid synovial fluid with rhomboid-shaped, weakly positively birefringent crystals. Diagnosis: Acute CPPD arthritis (pseudogout). Management: Exclude sepsis; NSAIDs (if tolerated) or colchicine; intra-articular steroid if persistent.
• Case 2 - Polyarticular Flares in Hospitalised Patient 🏥: An 80-year-old man develops acute swelling of both wrists and knees while admitted with pneumonia. Past history of CKD stage 3. X-ray: chondrocalcinosis in knees. Diagnosis: CPPD flare precipitated by intercurrent illness. Management: Colchicine (dose-adjusted for renal function), consider short course of oral steroids; treat underlying infection.
• Case 3 - Chronic Arthropathy Mimicking OA 🤔: A 69-year-old woman with years of progressive knee pain and stiffness, worse in the mornings, attends clinic. Exam: crepitus, bony enlargement, mild effusion. X-ray: joint space narrowing + chondrocalcinosis of menisci. Diagnosis: Chronic CPPD arthropathy (“pseudo-osteoarthritis”). Management: Analgesia, physiotherapy, weight reduction; colchicine prophylaxis if recurrent acute flares.

Teaching Commentary 🧠

CPPD disease = deposition of calcium pyrophosphate crystals in cartilage and joints. - Acute pseudogout: monoarthritis, often knee/wrist, mimics septic arthritis or gout. - Chronic CPPD arthropathy: mimics OA or RA, with atypical distribution. - Associations: haemochromatosis, hyperparathyroidism, hypomagnesaemia, hypothyroidism. - Dx: Synovial fluid microscopy (rhomboid, weakly positive birefringence), X-ray showing chondrocalcinosis. - Mx: NSAIDs, colchicine, steroids; prophylactic colchicine if recurrent.