Can I get an ultrasound (US) of a bump on a patient's temple after a negative temporal artery biopsy?

Ultrasound for Temple Bump After Negative Temporal Artery Biopsy

Yes, ultrasound imaging of the bump on the patient's temple is recommended after a negative temporal artery biopsy to aid in diagnosis and guide further management. 1

Rationale for Ultrasound After Negative Biopsy

The 2021 American College of Rheumatology/Vasculitis Foundation guidelines specifically state that for patients with suspected Giant Cell Arteritis (GCA) and a negative temporal artery biopsy result, noninvasive vascular imaging of the large vessels with clinical assessment is conditionally recommended to aid in diagnosis over clinical assessment alone 1. This recommendation is based on the understanding that:

• Temporal artery biopsy can miss GCA due to the focal and segmental nature of the disease
• A negative biopsy alone often does not lead to termination of steroid therapy in clinical practice 2
• Noninvasive imaging can detect vascular changes that may not be captured in the biopsied segment

Diagnostic Algorithm for Temple Bump After Negative Biopsy

1. Ultrasound evaluation of the temple bump

   • Look for characteristic findings:
     • Hypoechoic "halo" sign (edema of inflamed vessel wall)
     • Inflammatory stenoses
     • Occlusion patterns

2. Interpretation of ultrasound findings

   • Positive findings (halo or occlusion):

     • High specificity (91.9% for halo, 100% for occlusion) 3
     • Moderate sensitivity (53.3% for halo, 20% for occlusion)
     • Consider diagnosis of GCA despite negative biopsy

   • Negative findings:

     • High negative predictive value (95.8-100%) 4
     • Can help rule out GCA with greater confidence

Benefits of Ultrasound in This Scenario

• Non-invasive approach: No additional surgical procedure needed after already having a negative biopsy
• Cost-effective: Less expensive than other diagnostic methods (14,023 ± 982 ¥/patient vs. 18,551 ± 1231 ¥/patient for biopsy) 5
• Immediate results: Can be performed quickly, unlike biopsy which requires pathological processing
• May detect large vessel involvement: Can evaluate areas not accessible by biopsy

Limitations and Considerations

• Operator-dependent: Results are influenced by the experience and expertise of the ultrasonographer 1
• Treatment effect: Signs of inflammation quickly disappear with glucocorticoid treatment, potentially affecting results 1
• Regional expertise variations: In the US, there is generally less experience with temporal artery ultrasound compared to Europe 1

Clinical Implications

Ultrasound findings should be interpreted in conjunction with clinical assessment. If ultrasound shows positive findings despite negative biopsy, treatment for GCA may be warranted to prevent serious complications like vision loss. If both biopsy and ultrasound are negative, this provides stronger evidence to consider alternative diagnoses for the temple bump.