Is all inflammation within temporal artery biopsies temporal arteritis?

Age-related histopathological findings in temporal arteries

AIMS

Giant cell arteritis (GCA) is a systemic vasculitis affecting medium and large arteries in patients aged over 50 years. Involvement of temporal arteries (TA) can lead to complications such as blindness and stroke. While the diagnostic gold standard is temporal artery biopsy (TAB), comorbidities and age-related changes can make interpretation of such specimens difficult. This study aims to establish a baseline of TA changes in subjects without GCA to facilitate the interpretation of TAB.

METHODS AND RESULTS

Bilateral TA specimens were collected from 100 consecutive eligible postmortem examinations. Subjects were divided into four age groups and specimens semiquantitatively evaluated for eccentric intimal fibroplasia, disruption and calcification of the internal elastic lamina (IEL), medial attenuation and degree of lymphocytic inflammation of the peri-adventitia, adventitia, media and intima. The individual scores of intimal fibroplasia, IEL disruption and medial attenuation were added to yield a 'combined score (CS)'. Seventy-eight 78 decedents were included in the final analysis following exclusion of 22 individuals for either lack of clinical information or inability to collect TA tissue. A total of 128 temporal artery specimens (50 bilateral from individual decedents, 28 unilateral) were available for examination. Intimal proliferation, IEL loss, IEL calcification and CS increased with age in a statistically significant fashion. Comparison of the oldest age group with the others showed statistically significant differences, although this was not uniformly preserved in comparison between the three youngest groups.

CONCLUSION

Senescent arterial changes and healed GCA exhibit histological similarity and such changes increase proportionally with age. The CS demonstrates significant association with age overall and represents a potential avenue for development to 'normalise' TA biopsies from older individuals.

Consensus statement on the processing, interpretation and reporting of temporal artery biopsy for arteritis

Giant cell arteritis (GCA) is the most common systemic vasculitis in adults in Europe and North America, typically involving the extra-cranial branches of the carotid arteries and the thoracic aorta. Despite advances in noninvasive imaging, temporal artery biopsy (TAB) remains the gold standard for establishing a GCA diagnosis. The processing of TAB depends largely on individual institutional protocol, and the interpretation and reporting practices vary among pathologists. To address this lack of uniformity, the Society for Cardiovascular Pathology formed a committee tasked with establishing consensus guidelines for the processing, interpretation, and reporting of TAB specimens, based on the existing literature. This consensus statement includes a discussion of the differential diagnoses including other forms of arteritis and noninflammatory changes of the temporal artery.

Giant cell arteritis: reviewing the advancing diagnostics and management

Giant Cell Arteritis (GCA) is well known to be a critical ischaemic disease that requires immediate medical recognition to initiate treatment and where one in five people still suffer visual loss. The immunopathophysiology has continued to be characterised, and the influencing of ageing in the development of GCA is beginning to be understood. Recent national and international guidelines have supported the directed use of cranial ultrasound to reduce diagnostic delay and improve clinical outcomes. Immediate high dose glucocorticoids remain the standard emergency treatment for GCA, with a number of targeted agents that have been shown in clinical trials to have superior clinical efficacy and steroid sparing effects. The aim of this review was to present the latest advances in GCA that have the potential to influence routine clinical practice.

Temporal artery biopsy: A technical guide and review of its importance and indications

Temporal artery biopsy (TAB) is a surgical procedure that enables the histological diagnosis of giant cell arteritis (GCA). Performing a TAB requires expertise and a precise approach. Nevertheless, available data supports the value of tissue diagnosis in managing GCA. The current therapeutic recommendation for GCA is long-term glucocorticoid therapy, with an increasing emphasis on the addition of immunosuppressants/biotherapies. Though effective, immunosuppressants and other such biotherapies may put the patient at more risk. Optimizing the diagnosis through tissue evaluation is therefore important in weighing the risks and benefits of initiating therapeutic intervention. We evaluate the evidence supporting the importance of TAB and its indications. We also describe what technical approaches should be used to maximize sensitivity and to avoid possible complications during the procedure.

The Clinical Significance of Small Vessel Vasculitis on Temporal Artery Biopsies

BACKGROUND

Giant cell arteritis (GCA) is the most common type of systemic vasculitis in the elderly. Untreated, it can lead to irreversible blindness. Its diagnosis relies on a temporal artery biopsy (TAB). However, a proportion of patients have small vessel vasculitis (SVV) on biopsy; the prognosis of which remains unclear. The aim of this study is to compare the clinical presentation and long-term outcomes of those with SVV with negative and positive biopsies to determine whether long-term corticosteroid therapy can be avoided in these patients.

METHODS

Post hoc analysis of patients with suspected GCA who underwent TAB and fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan as part of a prospective GCA and PET cohort. Patients were divided in to 3 groups based on TAB result: positive (inflammation in the main artery wall), negative (no inflammation), and SVV (isolated vasa vasorum or periadventitial SVV). Clinical, serological, and PET/CT data of patients with SVV were compared with those with positive and those with negative biopsies.

RESULTS

For the 58 eligible patients recruited between May 2016 and December 2017, 11 had SVV, 12 had positive, and 35 had negative biopsies. Patients with SVV had similar clinical, serological, and PET/CT findings to those with negative biopsies. Compared with those with positive biopsies, patients with SVV had lower erythrocyte sedimentation rate (25 vs 78 mm/hour; P = 0.02), platelet count (296 vs 385 ×109/L; P = 0.03), and a lower median total vascular score on PET/CT scan (1.0 vs 13.5; P = 0.01). Median prednisone dose was lower (4.8 vs 11.7 mg; P = 0.015) and fewer were on steroid-sparing agents (20% vs 67%; P = 0.043) at 6 months. The percentage of patients with a clinical diagnosis of GCA was similar between those with SVV (3/11, 27.3%) and those with negative biopsies (5/35, 14.3%; P = 0.374).

CONCLUSIONS

Patients with SVV on TAB had similar clinical features, PET/CT findings, and 6-month outcomes to those with negative biopsies. Small vessel vasculitis can be treated as equivalent to a negative biopsy when being considered for diagnosis and treatment of GCA.

Temporal Artery Vascular Diseases

In the presence of temporal arteritis, clinicians often refer to the diagnosis of giant cell arteritis (GCA). However, differential diagnoses should also be evoked because other types of vascular diseases, vasculitis or not, may affect the temporal artery. Among vasculitis, Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis is probably the most common, and typically affects the peri-adventitial small vessel of the temporal artery and sometimes mimics giant cell arteritis, however, other symptoms are frequently associated and more specific of ANCA-associated vasculitis prompt a search for ANCA. The Immunoglobulin G4-related disease (IgG4-RD) can cause temporal arteritis as well. Some infections can also affect the temporal artery, primarily an infection caused by the varicella-zoster virus (VZV), which has an arterial tropism that may play a role in triggering giant cell arteritis. Drugs, mainly checkpoint inhibitors that are used to treat cancer, can also trigger giant cell arteritis. Furthermore, the temporal artery can be affected by diseases other than vasculitis such as atherosclerosis, calcyphilaxis, aneurysm, or arteriovenous fistula. In this review, these different diseases affecting the temporal artery are described.

Discordance Rate Among Bilateral Simultaneous and Sequential Temporal Artery Biopsies in Giant Cell Arteritis: Role of Frozen Sectioning Based on the Mayo Clinic Experience

Importance

Frozen section temporal artery biopsy (TAB) may prevent a contralateral biopsy from being performed.

Objective

To evaluate the sensitivity and specificity of TAB frozen vs permanent section pathology results for giant cell arteritis (GCA) and determine the discordance rate of bilateral TABs.

Design, Setting, and Participants

In this retrospective cohort study, medical records were reviewed from 795 patients 40 years or older who underwent TAB from January 1, 2010, to December 1, 2018, treated at a single tertiary care center with the ability to perform both frozen and permanent histologic sections. Data were analyzed from January 2019 to December 2020.

Main Outcomes and Measures

Sensitivity and specificity of frozen section TAB for detecting GCA, and discordance rates of bilateral permanent section TAB.

Results

Of the 795 included participants, 329 (41.4%) were male, and the mean (SD) age was 72 (10) years. From the 795 patients with 1162 TABs, 119 patients (15.0%) and 138 TABs had positive findings on permanent section. Of these 119 patients, 103 (86.6%) also had positive results on the frozen section, with 4 false-positives (0.6%) and 20 false-negatives (16.8%). Frozen section had a specificity of 99.4% (95% CI, 98.5-99.8), sensitivity of 83.2% (95% CI, 75.2-89.4), positive predictive value of 96.1% (95% CI, 90.4-98.9), negative predictive value of 96.6% (95% CI, 94.9-97.8), positive likelihood ratio of 140.6 (95% CI, 72.7-374.8), and a negative likelihood ratio of 0.17 (95% CI, 0.11-0.25). Simultaneous bilateral TABs were performed in 60 patients (7.5%) with a 5% discordance rate on permanent section. In comparison, bilateral frozen section-guided sequential TABs were performed in 307 patients (38.6%) with 5.5% discordance based on permanent section. In multivariate models, there was a greater odds of positive findings with age (odds ratio [OR], 1.04; 95% CI, 1.01-1.07; P = .008), vision loss (OR, 2.72; 95% CI, 1.25-5.75; P = .01), diplopia (OR, 3.33; 95% CI, 1.00-10.29; P = .04), headache (OR, 2.32; 95% CI, 1.25-4.53; P = .01), weight loss (OR, 2.37; 95% CI, 1.26-4.43; P = .007), and anorexia (OR, 5.65; 95% CI, 2.70-11.89; P < .001).

Conclusions and Relevance

These results support the hypothesis that negative findings from frozen sections should not be solely relied on to refute the diagnosis of GCA, whereas positive findings from frozen sections can be reliably used to defer a contralateral biopsy pending the permanent section results.

Clinicopathologic Associations in a Large International Cohort of Patients with Giant Cell Arteritis

OBJECTIVE

In addition to aiding in diagnosis, histopathologic findings from temporal artery biopsy (TAB) specimens in giant cell arteritis (GCA) may be valuable for their associations with clinical features of the disease. This study compared histopathologic findings on TAB with biopsy interpretation and demographic, clinical, and imaging features at time of diagnosis.

METHODS

Patients with a clinical diagnosis of GCA who had a TAB were selected from an international, multicenter observational cohort of vasculitis. Associations between demographic, clinical, radiographic, and histopathologic features were identified using bivariate testing and multivariate regression modeling.

RESULTS

Out of 705 patients with GCA who underwent TAB, 69% had histopathological evidence of definite vasculitis. Specific histopathological findings included the presence of giant cells (51%), fragmentation of the internal elastic lamina (41%), intimal thickening (33%), and predominantly mononuclear leukocyte infiltration (32%). Histopathologic interpretation of definite vasculitis was independently associated with giant cells (odds ratios (OR) 151.8, 95% confidence interval (CI): 60.2-551.6), predominantly mononuclear leukocyte infiltration (OR 11.8, CI 5.9-24.9), and fragmentation of the internal elastic lamina (OR 3.7, CI 1.9-7.4). A halo sign on temporal artery ultrasound and luminal damage of large arteries on angiography were significantly associated with presence of giant cells (OR 2.6, CI 1.1-6.5 and OR 2.4, CI 1.1-5.2, respectively). Specific histopathologic findings were associated with older age but no associations were identified with vision loss or other clinical features.

CONCLUSION

Histopathologic findings in GCA are strongly associated with the clinical diagnosis of GCA but have a limited role in identifying patterns of disease.

Significance of inflammation restricted to adventitial/periadventitial tissue on temporal artery biopsy

OBJECTIVE

To evaluate the characteristics and significance of inflammation restricted (RI) to the adventitial and/or periadventitial tissue on temporal artery biopsy (TAB).

METHODS

We studied a retrospective cohort of 80 patients with RI, extending our earlier series of 39 patients. For comparison purposes, we collected the same data from 254 patients with transmural inflammation (TMI) and 81 TAB-negative patients. A review of the literature was also performed.

RESULTS

A final diagnosis of giant cells arteritis (GCA) and/or polymyalgia rheumatica (PMR) was observed in 86% of patients with RI. Compared to TMI, GCA diagnosis was significantly less frequently observed in patients with RI and in those TAB-negative (p < 0.0001), while cranial manifestations were significantly less frequent (p = 0.001) and ESR and CRP values at diagnosis significantly reduced (p < 0.0001). PMR, permanent visual loss, and large vessel involvement at diagnosis were equally present in the 3 subgroups. The median duration of prednisone therapy, the cumulative prednisone dosages, and the relapse and long-term remission rates were similar between patients with GCA-RI and those with TMI. The positive likelihood ratios (LRs) of pathological evidence of RI at TAB for GCA or GCA/PMR diagnoses were 0.88 (CI, 0.61-1.27) and 1.15 (CI, 0.67-1.99), while that of inflammation limited to adventitia was 1.37 (CI, 0.59-3.19) and 3.77 (CI, 0.53-26.72). In the literature review, the positive LR of RI for GCA diagnosis was 0.92 (CI, 0.68-1.25).

CONCLUSION

A large part of the patients with RI have GCA/PMR, however, the diagnostic value of RI for GCA diagnosis is not relevant.

Diagnosis of giant cell arteritis

GCA is the most common form of primary systemic vasculitis affecting older people. It is considered a clinical emergency because it can lead to irreversible blindness in around 20% of untreated cases. High doses of glucocorticoids should be initiated promptly to prevent disease-related complications; however, glucocorticoids therapy usually results in significant toxicity. Therefore, correct diagnosis is crucial. For many years, temporal artery biopsy has been considered the diagnostic ‘gold standard’ for GCA, but it has many limitations (including low sensitivity). US has proven to be effective for diagnosing GCA and can reliably replace temporal artery biopsy in particular clinical settings. In cases of suspected GCA with large-vessel involvement, other imaging modalities can be used for diagnosis (e.g. CT and PET). Here we review the current evidence for each diagnostic modality and propose an algorithm to diagnose cranial-GCA in a setting with rapid access to high quality US.

Diagnostic performance and utility of very high-resolution ultrasonography in diagnosing giant cell arteritis of the temporal artery

OBJECTIVE

Very-high resolution US (VHRU; 55 MHz) provides improved resolution and could provide non-invasive diagnostic information in GCA of the temporal artery. The objective of this study was to assess the diagnostic utility of VHRU-derived intima thickness (VHRU-IT) in comparison to high-resolution US halo-to-Doppler ratio (HRU-HDR) in patients referred for temporal artery biopsy.

METHODS

VHRU and HRU of the temporal artery were performed before a biopsy procedure in 78 prospectively recruited consecutive patients who had received glucocorticoid treatment for a median of 8 days (interquartile range 0-13 days) before imaging. Based on the final diagnosis and biopsy findings, the study population was divided into the following four groups: non GCA (n = 40); clinical GCA with no inflammation on biopsy (n = 15); clinical GCA with inflammation limited to adventitia (n = 9); and clinical GCA with transmural inflammation (TMI; n = 11).

RESULTS

Both VHRU and HRU were useful for identifying subjects with TMI, with VHRU outperforming HRU (area under curve: VHRU-IT 0.99, 95% CI 0.97, 1.00; HRU-HDR 0.74, 95% CI 0.52, 0.96; P=0.026). The diagnostic utility for diagnosing clinical GCA (negative biopsy) or inflammation limited to the adventitia was poor for both VHRU and HRU-HDR. From 5 days after initiation of glucocorticoid treatment, VHRU-IT was increased in eight of nine patients, whereas HRU-HDR was positive in three of seven patients. Both methods showed excellent inter-observer agreement (Cohen's κ: VHRU-IT 0.873; HRU-HDR 0.811).

CONCLUSION

In suspected GCA, VHRU allows non-invasive real-time imaging of TMI manifestations of the temporal artery wall. VHRU-derived intimal thickness measurement seems to be more sensitive than the halo sign and HRU-HDR in detecting TMI in patients with prolonged glucocorticoid treatment.

Review: What Is the Current Evidence for Disease Subsets in Giant Cell Arteritis?

Giant cell arteritis (GCA) is an autoimmune vasculitis affecting large and medium‐sized arteries. Ample evidence indicates that GCA is a heterogeneous disease in terms of symptoms, immune pathology, and response to treatment. In the current review, we discuss the evidence for disease subsets in GCA. We describe clinical and immunologic characteristics that may impact the risk of cranial ischemic symptoms, relapse rates, and long‐term glucocorticoid requirements in patients with GCA. In addition, we discuss both proven and putative immunologic targets for therapy in patients with GCA who have an unfavorable prognosis. Finally, we provide recommendations for further research on disease subsets in GCA.

Why do temporal arteries go wrong? Principles and pearls from a clinician and a pathologist

Early diagnosis and treatment of GCA is essential to prevent complications of the disease, including permanent vision loss. Temporal artery biopsy has been intrinsically linked with the diagnosis of GCA for several decades. A negative predictive value of > 90% has been reported for temporal artery biopsy; however, a negative result does not reliably indicate the absence of GCA because inflammation of the temporal artery is not always evident because of segmental involvement or other reasons. This is demonstrated by a case study of a patient hospitalized following acute vision loss to the right eye whose glucocorticoid treatment was suspended after temporal artery biopsy revealed no evidence of GCA. The patient subsequently lost sight in the left eye 6 weeks after stopping glucocorticoid therapy. The specificity of temporal artery biopsy for the diagnosis of GCA is variable and influenced by many factors, including length of biopsy specimens, vasculitis in vessels other than the temporal artery (ophthalmic, retinal and posterior ciliary vessels), unilateral versus bilateral biopsy, expertise of the surgeon, interpretation of histology, effects of treatment and confounding factors such as atherosclerosis or other non-GCA diseases that can affect the temporal artery. Considering the limitations of temporal artery biopsy, collaboration and education between the clinician, the pathologist and the patient, taking into account a thorough examination of patient history, recognizing signs and symptoms, and potentially involving newer imaging studies with trained technicians and physicians, are essential in confirming or eliminating diagnosis of GCA.

Superficial temporal artery aneurysm associated with immunoglobulin G4-related disease

A 68-year-old man was admitted because of a pulsatile mass and pain in the left temporal region, and computed tomography demonstrated the superficial temporal artery aneurysm. He underwent aneurysmectomy, and pathologic investigation revealed marked thickness of the adventitia with substantial plasmacyte infiltration. On immunoglobulin G4 (IgG4) immunohistochemistry, IgG4-positive lymphocytes were scattered in the adventitia, and biochemical tests revealed elevation of IgG4 (200 mg/dL). The case satisfied the criteria for both giant cell arteritis and IgG4-related disease (IgG4-RD). This case report suggested that IgG4-RD can occur in the superficial temporal artery and that IgG4-RD may partially overlap with a subtype of giant cell arteritis.

Giant Cell Arteritis: Practical Pearls and Updates

PURPOSE OF REVIEW

The purpose of this review is to summarize recent updates and distill practical points from the literature which can be applied to the care of patients with suspected and confirmed giant cell arteritis (GCA).

RECENT FINDINGS

Contemporary thinking implicates a fundamental failure of T regulatory cell function in GCA pathophysiology, representing opportunity for novel therapeutic avenues. Tocilizumab has become the first Food and Drug Administration-approved treatment for GCA following demonstration of efficacy and safety in a phase 3 clinical trial. There have been significant parallel advances in both our understanding of GCA pathophysiology and treatment. Tocilizumab, and other agents currently under investigation in phase 2 and 3 clinical trials, presents a new horizon of hope for both disease remission and avoidance of glucocorticoid-related complications.

Poor Predictive Value of Isolated Adventitial and Periadventitial Infiltrates in Temporal Artery Biopsies for Diagnosis of Giant Cell Arteritis

OBJECTIVE

We investigated the diagnostic value of inflammation limited to the adventitia (ILA), and isolated vasa vasorum or small-vessel vasculitis (VVV, SVV) in temporal artery biopsies (TAB) for giant cell arteritis (GCA).

METHODS

Two pathologists reviewed consecutive first TAB. Using the clinical diagnoses as the gold standard, positive predictive values (PPV) were calculated.

RESULTS

Among the 75 patients without classic TAB features of GCA, 8 had GCA diagnoses. The PPV of ILA, VVV, and SVV seen by either or both pathologists were 17%, 0%, and 7%, and 17%, 0%, and 10%, respectively.

CONCLUSION

(Peri)adventitial infiltrates in TAB poorly predict GCA.