Patient: 74-year-old male farmer Presentation: 3-year history of progressive, painful swelling in the anterior compartment of right leg, enlarging masses over both elbows and dorsum of feet Relevant history: Longstanding gout (30 years), poorly controlled, multiple previous acute flares requiring colchicine, not on regular urate-lowering therapy, CKD stage 3 (eGFR 45), hypertension on thiazide diuretic Examination findings:
| Test | Result | Normal Range | Interpretation |
|---|---|---|---|
| Haemoglobin | 135 g/L | 130-170 | Normal |
| WCC | 8.5 × 10⁹/L | 4-11 | Normal |
| ESR | 25 mm/hr | 0-20 | Mildly elevated |
| CRP | 12 mg/L | <5 | Mildly elevated |
| Uric acid | 0.62 mmol/L | 0.20-0.42 | Elevated |
| Creatinine | 155 μmol/L | 60-110 | Elevated (CKD3) |
| eGFR | 45 mL/min | >90 | Reduced |
| Glucose | 6.2 mmol/L | 3.0-6.0 | Mildly elevated |
| Urinary uric acid | 4.8 mmol/24hr | 1.5-4.5 | Elevated (under-excretor) |
Image 1: Plain Radiographs - Feet AP and Lateral
Radiological features:
Image 2: Plain Radiograph - Right Leg
Radiological features:
Image 3: Dual-Energy CT (DECT) if available
DECT findings (if performed):
What is the diagnosis and what are the characteristic clinical features of tophaceous gout?
What investigations would you order to confirm the diagnosis and assess disease extent?
What is the pathophysiology of gout and why has this patient developed tophaceous disease?
How would you manage this patient medically? What urate-lowering therapy would you choose?
What are the indications for surgical management of tophi? How would you approach the leg mass?
What are the long-term complications and how do you monitor this patient?
This pattern suggests Tophaceous Gout:
Comparison - Gout vs Rheumatoid Nodules:
| Feature | Gouty Tophi | RA Nodules |
|---|---|---|
| Composition | MSU crystals | Fibrinoid necrosis |
| Location | MTP, olecranon, ear | Olecranon, extensor surfaces |
| X-ray | Punched-out erosions | Periarticular erosions |
| Crystals | Negatively birefringent | None |
| Serology | Normal RF | RF/anti-CCP positive |
| Joint space | Preserved | Narrowed early |
Q: "What is the mechanism of colchicine and why is it used for prophylaxis?"
| Aspect | Description |
|---|---|
| Mechanism | Inhibits microtubule polymerisation |
| Effect | Impairs neutrophil chemotaxis and phagocytosis |
| Result | Reduces inflammatory response to crystals |
| Prophylaxis | Prevents flares during ULT initiation |
| Duration | 3-6 months (longer for tophaceous) |
| CKD caution | Reduce dose; avoid with clarithromycin |
Q: "How do you manage an acute gout flare in this patient with CKD?"
| Option | Consideration for CKD |
|---|---|
| Colchicine | Reduce dose (0.5 mg BD), avoid if eGFR <30 |
| NSAIDs | Generally avoid in CKD |
| Prednisolone | Safe option - 20-30 mg tapering |
| IL-1 inhibitors | Anakinra if other options contraindicated |
| Joint aspiration | Reduces pain, confirms diagnosis |
Prednisolone is often the safest option in CKD.
Q: "What is the role of febuxostat vs allopurinol?"
| Aspect | Allopurinol | Febuxostat |
|---|---|---|
| First-line | Yes | No (second-line) |
| CKD | Dose-adjusted start, titrate | No adjustment needed |
| Efficacy | Good | May be more potent |
| CV safety | Established | CARES trial concern |
| Cost | Cheaper | More expensive |
| Indication | First-line | Allopurinol intolerance/failure |