In a 63‑year‑old woman with peripheral arterial disease, hypothyroidism, and taking gabapentin who presents with painful red burning hands, what is the most likely diagnosis and appropriate management?

Erythromelalgia: Most Likely Diagnosis with Specific Management Algorithm

This presentation is classic for erythromelalgia—a rare neurovascular disorder characterized by episodic red, burning hands (or feet) triggered by warmth, with relief from cooling. 1

Clinical Recognition

The triad of red, burning, and painful extremities distinguishes erythromelalgia from peripheral arterial disease, which typically presents with pallor, coolness, and absent pulses rather than erythema and warmth. 1

Key diagnostic features to confirm:

• Pain character: Burning, stinging quality (not claudication-type cramping) 1
• Color changes: Bright red or violaceous discoloration of affected areas 1
• Temperature sensitivity: Symptoms worsen with warmth/heat exposure and improve dramatically with cooling (patients often immerse hands in ice water) 1
• Bilateral distribution: Typically symmetric involvement 1
• Pulse examination: Pulses should be present and normal (this excludes critical limb ischemia) 1

Why This Is NOT Peripheral Arterial Disease

PAD would present with:

• Cool, pale extremities (not red and warm) 1
• Diminished or absent pulses 1, 2
• Pain relieved by dependency, worsened by elevation (opposite pattern from erythromelalgia) 2
• Claudication with exertion, not burning at rest 1, 2

The presence of warmth and erythema with burning pain makes arterial insufficiency extremely unlikely. 1, 2

Gabapentin's Role: Contributor or Treatment?

Gabapentin is actually a treatment option for neuropathic pain conditions including erythromelalgia, not a cause. 1, 3 However, at doses of 1800-3600 mg/day, gabapentin demonstrates efficacy for neuropathic pain syndromes with burning quality. 3

If the patient's current gabapentin dose is subtherapeutic (<1800 mg/day), consider titration rather than discontinuation. 3

Hypothyroidism Connection

Hypothyroidism should be optimally treated in this patient, as thyroid dysfunction can exacerbate vascular symptoms and neuropathic conditions. 4 Verify TSH is at goal and adjust levothyroxine accordingly. 4

Immediate Diagnostic Steps

1. Verify adequate arterial perfusion to exclude PAD masquerading as erythromelalgia:

   • Palpate bilateral brachial, radial, ulnar, dorsalis pedis, and posterior tibial pulses (should be grade 2 = normal) 1
   • Measure ankle-brachial index (ABI) bilaterally (should be 0.90-1.40; <0.90 indicates PAD) 1, 2
   • Inspect hands for trophic changes, ulcerations, or tissue loss (should be absent in erythromelalgia) 1

2. Assess for secondary causes of erythromelalgia:

   • Complete blood count to exclude myeloproliferative disorders (especially essential thrombocythemia and polycythemia vera, which cause secondary erythromelalgia) 1
   • Confirm hypothyroidism is adequately treated with TSH measurement 4

Management Algorithm

If ABI is Normal (0.90-1.40) and Pulses Present:

Primary erythromelalgia is confirmed. Initiate the following stepwise approach:

1. Non-pharmacologic measures (first-line):

   • Avoid heat exposure and triggers (hot weather, exercise, warm environments) 1
   • Elevate affected extremities 1
   • Use cooling techniques cautiously (avoid ice water immersion causing tissue damage; use fans or cool water instead) 1

2. Optimize gabapentin dosing:

   • If current dose <1800 mg/day, titrate to 1800 mg/day divided three times daily (600 mg TID) 3
   • May increase to 3600 mg/day if inadequate response at 1800 mg/day 3
   • Titration schedule: Start 900 mg/day (300 mg day 1,600 mg day 2,900 mg day 3), then increase by 300 mg every 1-3 days as tolerated 3

3. Consider aspirin trial:

   • Low-dose aspirin 81-325 mg daily may provide relief, particularly if myeloproliferative disorder is suspected 1
   • Also provides cardiovascular protection given PAD history 5, 6

4. Refractory cases: Refer to neurology or pain specialist for consideration of:

   • Topical agents (capsaicin, lidocaine) 1
   • Alternative neuropathic pain agents (tricyclic antidepressants, SNRIs) 1, 3

If ABI <0.90 or Pulses Diminished:

This would indicate coexistent PAD requiring different management:

• Refer urgently to vascular specialist if ABI <0.4 or tissue loss present 2, 7
• Initiate cardiovascular risk reduction: high-intensity statin (targeting LDL <55 mg/dL), antiplatelet therapy (aspirin 81 mg or clopidogrel 75 mg daily), blood pressure control to <140/90 mmHg 2, 5, 6
• However, burning erythematous hands with warmth would be atypical for PAD alone and suggests a mixed picture 1, 2

Critical Pitfalls to Avoid

• Do not assume PAD based solely on the patient's history of peripheral arterial disease—the symptom pattern (red, burning, warm) is inconsistent with arterial insufficiency, which causes pale, cool extremities. 1, 2
• Do not discontinue gabapentin without ensuring adequate dosing first—therapeutic doses for neuropathic pain are 1800-3600 mg/day, and many patients receive subtherapeutic doses. 3
• Do not overlook myeloproliferative disorders—obtain CBC to exclude secondary erythromelalgia from essential thrombocythemia or polycythemia vera. 1
• Do not recommend ice water immersion—while patients often self-treat this way for immediate relief, prolonged cold exposure can cause tissue damage; recommend fans or cool (not ice) water instead. 1