In a patient over 50 years old with new temporal headache, scalp tenderness, jaw claudication, polymyalgia-like symptoms, fever, weight loss, and elevated erythrocyte sedimentation rate and C‑reactive protein, how should giant cell arteritis be diagnosed and managed, including initial glucocorticoid therapy and the role of tocilizumab?

Giant Cell Arteritis: Diagnosis and Management

Immediate Action When GCA is Suspected

Start high-dose oral glucocorticoids (prednisone 40-60 mg daily) immediately when clinical suspicion is high—do not wait for biopsy confirmation, as irreversible vision loss can occur within hours to days. 1, 2

• For patients presenting with visual symptoms (transient vision loss, diplopia, blurred vision) or threatened vision loss, escalate to IV methylprednisolone 500-1000 mg daily for 3 consecutive days before transitioning to oral prednisone 2, 3
• Glucocorticoid therapy remains effective even if started before biopsy, as histopathologic changes persist for 1-2 weeks after treatment initiation 2

Clinical Diagnosis: Key Features to Identify

High-Specificity Symptoms (Rule In Disease)

• Jaw claudication (LR+ 4.90)—the most specific symptom, present in ~50% of patients 2
• Temporal artery abnormalities: thickening (LR+ 4.70), loss of pulse (LR+ 3.25), or tenderness on palpation 2
• Scalp tenderness (LR+ 3.14) 2

Common Presenting Features

• New-onset headache in patients >50 years (present in 67-90% of biopsy-confirmed cases) 2
• Visual disturbances occur in 20% before permanent vision loss 2
• Constitutional symptoms: fever, weight loss, malaise 1
• Polymyalgia rheumatica symptoms (shoulder/hip girdle pain and stiffness) 1

Laboratory Markers

• ESR >40 mm/h and CRP ≥2.5 mg/dL are elevated in >95% of cases 2, 4
• ESR >100 mm/h has LR+ 3.11 2
• Normal ESR (<40 mm/h) has negative LR 0.18; normal CRP (<2.5 mg/dL) has negative LR 0.38—making GCA unlikely if both are normal 2
• Platelet count >400 × 10³/μL has LR+ 3.75 2

Diagnostic Confirmation

Temporal Artery Biopsy (Gold Standard)

• Obtain biopsy within 2 weeks of starting glucocorticoids 2
• Specimen must be ≥1 cm in length to minimize false negatives from skip lesions 1, 2, 3
• Requires experienced surgeon and pathologist 1, 2
• Contralateral biopsy only if initial biopsy negative and clinical suspicion remains high 2
• Histopathology shows: arterial wall thickening, narrowed lumen, mononuclear inflammatory cell infiltration of media, and occasionally multinucleated giant cells 1, 4

Vascular Imaging (Alternative/Adjunctive)

• Temporal artery ultrasound showing "halo sign" (circumferential wall thickening): 88% sensitivity, 97% specificity when performed by experienced operators 2
• Large vessel imaging (MR/CT angiography of neck/chest/abdomen/pelvis or PET-FDG) to identify extracranial involvement, which occurs in substantial proportion of patients 1
• Imaging particularly important for large-vessel GCA, which presents less frequently with cranial symptoms and has higher relapse rates 1

Initial Glucocorticoid Management

Dosing Strategy

• Standard dose: Prednisone 40-60 mg daily orally 1, 2
• Vision-threatening disease: IV methylprednisolone 1000 mg daily × 3 days, then transition to oral prednisone 2, 3
• Maintain initial high dose for 1 month before beginning taper 2

Tapering Protocol

• Target 10-15 mg daily at 3 months 2
• Target ≤5 mg daily at 1 year if disease controlled 2
• Taper guided by clinical symptoms and inflammatory markers (ESR/CRP), not IL-6 levels 2
• Treatment typically required for 1-2 years to prevent recurrence 2

Tocilizumab: Glucocorticoid-Sparing Therapy

Add tocilizumab as adjunctive therapy to reduce glucocorticoid requirements and prevent disease relapse. 1, 2, 5

Evidence Base

• Tocilizumab (IL-6 receptor antagonist) is FDA-approved for GCA 1
• Weekly tocilizumab vs placebo + 52-week steroid taper: 3.17-fold higher sustained remission rate at 12 months (RR 3.17,95% CI 1.71-5.89) 5
• Every-other-week tocilizumab vs placebo + 52-week taper: 3.01-fold higher sustained remission (RR 3.01,95% CI 1.57-5.75) 5
• Reduces need for escape therapy and extends relapse-free survival 5

When to Use Tocilizumab

• Preferred adjunctive agent for all patients to minimize glucocorticoid exposure 1, 2
• Especially important for patients with ischemic complications (stroke, vision loss) 3
• Consider at diagnosis rather than waiting for relapse 1, 2

Alternative Immunosuppressive Agents

• Methotrexate: second-line steroid-sparing agent when tocilizumab unavailable or contraindicated 2, 3
• Abatacept: reasonable alternative adjunctive therapy 2

Adjunctive Cardiovascular Protection

Prescribe low-dose aspirin 75-150 mg daily for all GCA patients to reduce cardiovascular and cerebrovascular events. 2, 3

Monitoring and Follow-Up

Clinical Monitoring

• Regular assessment of symptoms (headache, vision, jaw claudication) 1, 2
• Serial ESR and CRP measurements to guide treatment decisions 1, 2
• Monitor for glucocorticoid-related adverse effects 1

Imaging Surveillance

• Periodic vascular imaging for patients with known large-vessel involvement to assess for aneurysms, stenoses, and lesion stability 2
• Patients without large-vessel involvement may not require routine repeated imaging 2

Bone Protection

• Initiate calcium, vitamin D, and bisphosphonates for all patients on glucocorticoids unless contraindicated 2

Management of Disease Relapse

Up to 60% of patients experience relapses during glucocorticoid tapering. 3

Relapse Management Algorithm

• Escalate glucocorticoid dose to regain disease control 2
• Add or switch immunosuppressive agent if relapse occurs despite adequate glucocorticoid therapy 2
• Consider switching from methotrexate to tocilizumab or adding abatacept 2

Critical Pitfalls to Avoid

• Never delay glucocorticoids while awaiting biopsy—untreated GCA carries 14-50% risk of permanent vision loss 1, 2
• Do not rely on normal inflammatory markers alone to exclude GCA—some patients present with normal ESR, though this is uncommon 6, 7
• Do not obtain biopsy specimens <1 cm—skip lesions cause false negatives 1, 2
• Do not use traditional ACR classification criteria alone for large-vessel GCA—they underperform in extracranial disease; imaging is essential 1
• Do not taper glucocorticoids too rapidly—most relapses occur during tapering phase 3