Tophaceous Gout
CIM Case: Tophaceous Gout
Clinical Scenario
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:
- Large irregular subcutaneous mass anterior right leg (8 x 5 cm), firm, non-tender, chalky material visible through thin overlying skin
- Multiple smaller tophi over olecranon bursa bilateral
- Tophi dorsum of feet bilateral, overlying 1st MTP joints
- Chronic deformity 1st MTP joints bilateral (hallux valgus appearance)
- Limited ROM 1st MTP, subtalar joints bilateral
- Skin over some tophi thin, whitish material visible
- No acute inflammation currently
- No fever, systemically well
Investigations Provided
Laboratory Results
| 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) |
Imaging
Image 1: Plain Radiographs - Feet AP and Lateral
Radiological features:
- Punched-out erosions 1st MTP joints bilateral (overhanging edges)
- Soft tissue swelling with calcification over 1st MTP
- Joint space narrowing 1st MTP bilateral
- Preserved joint space elsewhere initially
- Periarticular osteopenia minimal
- No acute fracture
Image 2: Plain Radiograph - Right Leg
Radiological features:
- Large soft tissue mass anterior leg
- Dense calcified deposits within mass
- No underlying bone erosion
- Soft tissues otherwise normal
Image 3: Dual-Energy CT (DECT) if available
DECT findings (if performed):
- Monosodium urate deposits colour-coded green
- Extensive urate deposition around 1st MTP joints
- Urate deposits within anterior leg mass
- Additional deposits at elbow, Achilles insertion
Questions & Model Answers
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?
Key Teaching Points
Pattern Recognition
This pattern suggests Tophaceous Gout:
- Long history of recurrent gout
- Subcutaneous nodules at characteristic sites (olecranon, 1st MTP, Achilles)
- Chalky material visible through skin
- Chronic joint deformity
- Elevated serum uric acid
- Characteristic X-ray findings (punched-out erosions, overhanging edges)
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 |
Critical Management Points
- Target uric acid <0.30 mmol/L - lower target for tophaceous disease
- Start low, go slow with allopurinol - especially in CKD
- Flare prophylaxis essential - 3-6 months minimum
- Stop thiazide if possible - major contributor to hyperuricaemia
- Surgery is palliative - medical therapy remains cornerstone
- Tophi dissolve with treatment - patient education and adherence key
Common Examiner Follow-ups
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 |
Related Topics
- Gout and Acute Gouty Arthritis
- Crystal Arthropathies
- Pseudogout (CPPD)
- Chronic Kidney Disease and Orthopaedics
- Metabolic Bone Disease