Temporal Artery Biopsy Research Articles

Inflammation of the temporalis muscle and adjacent nerve tissue in giant cell arteritis: expanding the spectrum of inflammatory lesions.

To investigate the histopathological features of the temporalis muscle (TM) and adjacent nerve tissue in active cranial giant cell arteritis (C-GCA). Temporal artery biopsy (TAB) specimens containing fragments of the TM from patients with active C-GCA fulfilling the 2022 ACR/EULAR classification criteria (n = 11) were assessed by conventional histology and immunohistochemistry in comparison with non-GCA controls (n = 3). Clinical, laboratory and imaging features based on patient charts at time of biopsy were retrospectively recorded. The majority of the studied TAB specimens showed inflammation of the TM (10/11) and adjacent nerve fascicles (7/11) that was characterized by prominent endomysial lymphomonocytic infiltrates, whereas controls showed no inflammatory lesions and no disruption of the local architecture. Association of active C-GCA with sarcolemmal MHC class I (8/8) and MHC class II (6/11) upregulation suggests primary inflammation of the TM in a subset of patients. αB-Crystallin positivity (10/11) highlights areas of pre-necrotic myofibres within the TM. The presence of endomysial fibrosis, signs of atrophy and variations of muscle fibre size suggest a rather longstanding and potentially subclinical process of myoinflammation. Our results expand the spectrum of inflammatory lesions known to be associated with active C-GCA. Specifically, inflammatory infiltration of the TM and adjacent nerve structures could contribute to localized symptoms of the temporomandibular region and may be included in future concepts of pathophysiology.

Serial assessment of ultrasound sensitivity and scores in patients with giant cell arteritis before and 3 and 10 days after treatment.

To evaluate sensitivity and scores of vascular ultrasound (US) before and after initiating glucocorticoid (GC) treatment in patients with new-onset giant cell arteritis (GCA). Treatment-naïve patients with GCA were prospectively included. 18F-FDG PET/CT, US and temporal artery (TA) biopsy were performed in all patients. US was repeated 3 and 10 days after GC commencement. Intima-media thickness and presence of halo signs were assessed. Sonographers were unblinded to clinical data. The OMERACT GCA Ultrasonography score (OGUS) and halo count (HC) were calculated. Forty-eight patients were included. Before GC exposure, US sensitivity was 94% (95% CI: 83-99), 73% (95% CI: 58-85) and 71% (95% CI: 56-83) when assessing all vessels, TAs, and large vessels (LVs), respectively. At day 3 and 10, overall US sensitivity was 92% (95% CI: 78-98, p= 0.16) and 83% (95% CI: 69-92, p= 0.10), respectively. At day 10, TA-US and LV-US sensitivity was 53% (95% CI: 38-68, p< 0.01), and 60% (95% CI: 44-74, p= 0.13), respectively. Median OGUS decreased from 1.06 (IQR 0.83-1.24)-0.95 (IQR 0.78-1.14, p< 0.01), and 0.90 (IQR 0.73-1.01, p< 0.001) after 3 and 10 days, respectively. Median HC decreased from 3 (IQR 2-5)-2 (IQR 1-4, p< 0.01) after 10 days. The vasculitic US findings expressed by OGUS diminish after 3 days of GC treatment. TA-US sensitivity decreased after 10 days, whereas LV-US was less likely to change, highlighting the importance of LV-assessment. Consistent with the EULAR recommendations, these findings encourage prompt US assessment, preferably within 3 days, to ensure an accurate diagnosis.

Vasculitis associated with VEXAS syndrome.

To define the prevalence, distribution, and characteristics of patients with VEXAS who have confirmed vasculitis. Patients with VEXAS syndrome, verified by positive UBA1 mutation, were included. Chart review was performed to identify. characteristics and outcomes. Vasculitis diagnosis was based on either histopathology showing vascular inflammation or non-invasive angiography findings. Summary statistics were calculated. Eighty-nine patients met inclusion criteria. All were male with a median age of onset of 66.9 years (IQR 60.1, 72.7). Median (IQR) follow up was 3.8(2.2-5.5) years during which 21 patients (23.6%) had evidence of vasculitis. Vasculitis subtypes included small vessel vasculitis (19.1%), cutaneous medium vessel vasculitis (2.2%), and large vessel vasculitis (2.2%). No patient had more than one vessel size involved. Histopathology in small vessel vasculitis patients was consistent with cutaneous leukocytoclastic vasculitis in the majority, though one patient had leukocytoclastic peritubular capillaritis on renal biopsy. Cranial symptoms (headache, vision changes, or jaw pain) were noted in 18.0%. Two additional patients not experiencing cranial symptoms exhibited large vessel involvement with confirmed carotid thickening on non-invasive angiography; one of these had a positive temporal artery biopsy. VEXAS syndrome manifests as a variable vessel vasculitis in a quarter of patients, with cutaneous small and medium vessel involvement being particularly common. Some patients may have positive ANCA serologies or even renal vasculitis leading to misdiagnosis. Cranial symptoms are common and may mimic giant cell arteritis, though documented large vessel inflammation is rare.

Five-Year Data from the Interdisciplinary Giant-Cell Arteritis Registry at the University Hospital of Würzburg: Value of Temporal Artery Biopsy.

Giant-cell arteritis (GCA) requires immediate diagnosis and therapy. The University Hospital of Würzburg established the Centre for Giant-cell Arteritis (ZeRi) to improve interdisciplinary collaboration. Retrospective evaluation of five-year data to assess the clinical relevance of several diagnostic methods, including temporal artery biopsy. Retrospective evaluation of 101 patients with suspected GCA who had undergone interdisciplinary examination and biopsy between 2017 and 2022. We analysed specificity and sensitivity in clinical symptoms, ESR, CRP, scalp MRI, temporal artery sonography, and temporal artery biopsy. GCA was diagnosed after completing diagnostic testing in 75 of 101 patients with suspected GCA. By definition, biopsy showed a positive predictive value of 100% and a specificity of 84.6%; however, negative predictive value was 51.2%. Sonography of the temporal artery and MRI showed a positive predictive value of more than 93% and sensitivity of 62.5% and 76.1%, respectively. Clinical symptoms showed the highest sensitivity at 92% with a specificity of 57.7%. ESR and CRP were significantly higher in patients with GCA than in patients without GCA, whereby CRP values showed higher predictive power than did ESR. Most GCA cases can be detected with a precise medical history as well as ESR and CRP assessment. Sonography and MRI on the scalp can usually confirm suspected GCA, only requiring temporal artery biopsy in exceptional cases.

Diagnostic sensitivity of temporal artery biopsy for giant cell arteritis: a retrospective study

Diagnostic sensitivity of temporal artery biopsy for giant cell arteritis: a retrospective study

Temporal artery biopsy in giant cell arteritis: clinical perspectives and histological patterns.

Although its role has been debated, temporal artery biopsy (TAB) remains the gold standard for the diagnosis of cranial giant cell arteritis (GCA). The specificity of TAB is excellent and the sensitivity, albeit lower, is comparable with other diagnostic modalities used for the diagnosis of GCA. This outpatient procedure has a low rate of complications and is well integrated in the majority of healthcare systems. The length of the specimen, the number of the examined sections and the prolonged use of glucocorticoids before the biopsy may affect the outcome of the TAB as diagnostic tool. The typical histological findings in GCA are often characterized by granulomatous inflammation with infiltration of mononuclear cells with or without the presence of giant cell, varying degrees of external and internal elastic lamina damage and intimal thickening. Overlooking signs of inflammation in the adventitia and in connective tissue surrounding the temporal artery may lead to false negative results. The distinction between healed arteritis and age-related atherosclerosis may be challenging.

Genes deregulated in giant cell arteritis by Nanostring nCounter gene expression profiling in temporal artery biopsies

ObjectiveTo identify differentially expressed genes in temporal artery biopsies (TABs) from patients with giant cell arteritis (GCA) with different histological patterns of inflammation: transmural inflammation (TMI) and inflammation limited to...

Giant Cell Arteritis: Can Simple Ultrasound Examination Prevent Complex Consequences?

Giant cell arteritis (GCA) is a rare disease of the arteries, occurring mainly in the elderly. Although the involvement of temporal arteries can be mostly symptomatic, the occlusion of ophthalmic arteries has severe consequences. GCA affecting temporal arteries is an emergency requiring quick commencement of treatment with glucocorticoids due to the serious consequences of neglect-blindness. According to the new guidelines released by EULAR, ultrasound is the tool of choice in support of the clinical diagnosis of giant cell arteritis, replacing temporal artery biopsy (TAB), as it is a sensitive and non-invasive method that is widely available. The main limitation is that the reliability of this imaging is based on the technical expertise of ultrasonographers. However, performing imaging should not delay commencing the treatment. In this work, we present ultrasound images from a case report of a 74-year-old female patient where difficulties in establishing a diagnosis led to vision loss in both eyes. In this example, we describe the ultrasound findings in giant cell arteritis, emphasizing its usefulness in supporting a diagnosis of GCA.

Ultrasonography led multimodal diagnostic pathway for giant cell arteritis.

To establish the sensitivity and negative predictive value of a multimodal pathway incorporating ultrasonography, 18-fluorodeoxyglucose labelled positron emission tomography computed tomography and temporal artery biopsy for the diagnosis of giant cell arteritis. 1000 consecutive referrals for a new diagnosis of giant cell arteritis were analysed. All patients had a protocolized examination. Patients with a negative ultrasonography and a C-reactive protein of ≥ 20 mg/l received an extended ultrasound examination. If that was negative, and there was no other explanation for their presentation, a second test in the form of either a temporal artery biopsy or an 18-fluorodeoxyglucose labelled positron emission tomography computed tomography was offered. We calculated the sensitivity and negative predictive value of the interventions for diagnosing giant cell arteritis. 279/1000 patients had positive ultrasonography for giant cell arteritis. 202 had bilateral superficial temporal arterial involvement. Ultrasonography of the axillary artery and other head/neck arteries increased the yield by 53 and 24 patients respectively. 181 patients were referred for a second test. 24/139 temporal artery biopsies and 7/42 18-fluorodeoxyglucose labelled positron emission tomography computed tomography scans were positive. The sensitivity and negative predictive value rise from 62.3% and 84.7% respectively for imaging superficial temporal arteries alone, to 95.7% and 98.0% respectively for extended ultrasonography plus a second test. This is the first real world evidence of the utility of ultrasonography for the diagnosis of giant cell arteritis as part of a multimodal diagnostic pathway.

Imaging in vasculitis.

Systemic vasculitides are characterized by inflammation of blood vessels. Their classification is based on the size of the blood vessels involved - large, medium, or small. Vasculitis early diagnosis and reliable monitoring are crucial to establish a treatment plan and prevent serious complications. Based on these considerations and depending on the location of the affected vessels, the importance of imaging modalities including ultrasonography (US), magnetic resonance Imaging (MRI), magnetic resonance angiography (MRA), computed tomography (CT), computed tomography angiography (CTA), and [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) has progressively increased. In addition to physical exam and laboratory data, these imaging tools offer complementary information about vascular changes occurring in vasculitis.This review summarizes the different imaging modalities being utilized to diagnose and monitor vasculitis. The most recent update for the use of imaging in vasculitis is referenced in the 2023 European Alliance of Associations for Rheumatology (EULAR) recommendations and the American College of Rheumatology (ACR) guidelines in 2021. Recent advances in PET imaging in large vessel vasculitis include improved technological imaging acquisition and the use of novel radiotracers for cellular and immune targets. FDG-PET has now been demonstrated to have high sensitivity and specificity to detect temporal arteritis. Imaging plays a significant role in the evaluation of vasculitis and continues to gain importance in the diagnosis and monitoring of disease activity. Differences exist between the ACR guidelines, which advocates for temporal artery biopsy, and the EULAR guidelines, which favors imaging modalities for the initial evaluation and diagnosis of large vessel vasculitis (LVV). Prerequisites for appropriate clinical management utilizing imaging in patients with vasculitis are the availability and access to skilled clinicians to interpret the images and the cost of these techniques not being prohibitive.

News on the imaging of large vessel vasculitis

Large vessel vasculitis, including giant cell arteritis (GCA) and Takayasu arteritis (TAK), are autoimmune diseases primarily affecting the aorta and its branches. GCA is the most common primary vasculitis. Inflammatory changes in the vessel walls can cause serious complications such as amaurosis, stroke, and aortic dissection and rupture. Imaging techniques have become an integral part for the diagnosis and monitoring of large vessel vasculitis, allowing for effective disease monitoring. GCA and TAK exhibit similar patterns of vascular distribution. However, the temporal arteries are never involved in TAK, and axillary arteritis occurs more frequently in GCA. In most centers, ultrasound of the temporal and axillary arteries has replaced temporal artery biopsy as the primary diagnostic tool for GCA. In addition to ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and [18F]-FDG (fluorodeoxyglucose) positron emission tomography-computed tomography (PET) are important, particularly for visualizing the aorta. Moreover, PET-CT is now also capable of assessing the temporal arteries, although it is not yet widely available. In polymyalgia rheumatica (PMR), ultrasound of the shoulder and hip regions is part of the ACR/EULAR classification criteria. MRI allows detailed visualization of additional inflammatory extraarticular manifestations, showing characteristic inflammatory lesions in entheses, tendons, and ligaments. [18F]-FDG-PET-CT also enables the visualization of musculoskeletal inflammation, especially in the shoulder and hip regions, as well as paravertebral areas. Ultrasound can detect subclinical GCA in up to 23% of patients with PMR, which should be treated like GCA. Technological innovations such as new radiotracers and improved MRI imaging could further enhance the diagnosis and monitoring of large vessel vasculitis and PMR, thus playing acrucial role in improving the prognosis through faster initiation of therapy.

ThP8.12 - To do or not to do-Temporal artery Biopsy in Giant Cell arteritis

Abstract Aims Temporal artery biopsy (TAB) remains the gold-standard diagnostic test for giant cell arteritis (GCA). Our aim is to evaluate the correlation between initiation of corticosteroid therapy, timing of biopsy, and histological diagnosis of GCA through TAB. Moreover, analyse the usefulness of this practice. Methods Operative notes of TABs performed by a Vascular Surgery department at a teaching hospital between August 2021 and January 2023 were reviewed. We looked into the relationship between histological findings and the timing of corticosteroid treatment initiation prior to TAB. Results A total of eight patients had a TAB, with a male-to-female ratio of 2:6. The median age of the patients was 68-years-old (range 53-84). TABs were performed within 16 days of the referral (range 2-16). All were performed on elective theatre lists and none on emergency theatre lists (CEPOD). All patients had started corticosteroids by the time they had TAB, with a median duration of 11.5 days before TAB (range 2-16). The histopathology report was positive for active GCA in 1 case (12.5%) where the TAB was performed on day 3. In another performed on day 16, histopathology showed signs of healed inflammation (12.5%). In all other cases the report was negative (75%). All patients completed a full weaning course of steroids regardless of histological findings. Conclusion GCA is a systemic inflammatory vasculitis. Prompt initiation of high-dose corticosteroids is the mainstay management to reduce risks of ischaemic-related complications. Our work suggests the timing of biopsy is a key determinant of histological diagnosis of GCA.

ThP8.7 - Giant Cell Arteries: Diagnostics

Abstract Aim Giant cell arteritis (GCA) poses a risk of severe ischaemic complications such as irreversible blindness which mandates early recognition of condition. We aimed to evaluate effectiveness of ultrasound doppler (USD) in diagnosing GCA compared to temporal artery biopsy (TAB) and American College of Rheumatology (ACR) score. Method This retrospective study included patients with suspected GCA who had consecutive TAB and USD examinations performed over a course of three years (2017-2022) which was correlated with ACR score. The data was also analysed to assess further management. Results There were 64 patients over this period who had both studies performed (22 were excluded as they did not have TAB) with 64% having an ACR score ≥3. Twenty males and forty-four females with a median age of 77 years (IQR 84-67). Overall, 81% patients had a negative USD result. Comparing USD results with TAB gold standard, there was sensitivity of 63% and specificity of 84%. Comparing USD results with ACR as gold standard, there was sensitivity of 20% and specificity of 83%. Forty percent patients with negative doppler result were continued on treatment mainly due to improvement of symptoms in response to steroids. Conclusion US Doppler has high diagnostic specificity and low sensitivity which makes it time-efficient, cost-effective and allows for the implementation of fast-track management pathway for majority patients. In certain circumstances, as cases of low clinical suspicion and positive doppler result, an additional test (TAB) would be required to confirm the diagnosis and cases where clinical suspicion is high with negative doppler, TAB should be considered.

The impact of histopathological criteria for definite vasculitis in giant cell arteritis: retrospective analysis of temporal artery biopsies.

Histopathological findings associated with definite vasculitis in temporal artery biopsy (TAB) defined in 2022 ACR/EULAR classification criteria for Giant Cell Arteritis (GCA) was published in 2022. We aimed to evaluate the TAB of our GCA patients for histopathological findings associated with definite vasculitis. Patients who were diagnosed with GCA by clinicians and underwent TAB between January 2012 and May 2022 were included. Hospital electronic records and patients' files were reviewed retrospectively. A total of 90 patients' pathology reports were evaluated by a pathologist and a rheumatologist. In cases where microscopic findings were not specified in the pathology reports, histopathologic specimens were re-evaluated (n = 36). A standard checklist was used for histopathological findings of definite vasculitis. Patients were divided into two groups; (i) definite vasculitis-GCA and (ii) non-definite-GCA group, and the clinical and demographic characteristics for all patients were compared. The mean age of patients was 69.8 (± 8.5) years and 52.2% were female. In the first evaluation, 66 (73.3%) patients had a diagnosis of vasculitis according to pathology reports. In the re-evaluation of biopsy specimens, at least one definite finding of vasculitis was observed in TAB of 10/24 (41.6%) patients whose microscopic findings were not specified in the pathology reports. The ROC analysis showed that biopsy length had diagnostic value in predicting the diagnosis of definite vasculitis (AUC: 0.778, 95% CI: 0.65-0.89, p < 0.001). In those with a biopsy length of ≥ 1cm, sensitivity was 76.5%, specificity was 64.3%, and PPV value was 92. In multivariate analysis, the most significant factor associated with definite vasculitis was biopsy length (OR: 1.18 (1.06-1.31), p = 0.002). Microscopic findings were reported in over 70% of patients. Reinterpretation of results according to a standard check-list improved the impact of TAB in the diagnosis of GCA. A biopsy length ≥ 1cm was found to contribute towards a definitive histopathological vasculitis diagnosis.

Retrospective Analysis of Specimen Quality in Temporal Artery Biopsies for Giant Cell Arteritis and Disease Association in North Midlands, England.

Background Temporal artery biopsy (TAB) is the recommended index diagnostic method for giant cell arteritis (GCA). Per the British Society for Rheumatology (BSR) guidelines, we assessed our procedural performance. Additionally, we evaluated the occurrence of GCA diagnosis in immunosuppressed patients and other comorbidities. Methods Following the audit registration, a retrospective analysis of prospectively collected data was conducted from 2017 to 2022 at a large university hospital in North Midlands, England. Data on demographics and comorbidities were gathered. The study's primary outcome was adherence to BSR guidelines and our service provisions. Secondary outcomes included examining the relationship between biopsy-confirmed GCA and other comorbidities. Statistical analysis was carried out using SPSS version 29 (IBM Corporation, Armonk, New York, United States of America). Two-sample t-test and Chi-square/Fisher exact test were used for continuous and categorical variables, respectively. Holm-Bonferroni method was incorporated to adjust for multiple comparisons. Results A total of 156 patients who underwent temporal artery biopsy (TAB) were included in the study, with a male-to-female ratio of 0.44:1. The median age was 73. Among the patients, 19% were smokers. The procedures were performed by either a vascular surgeon (119, 76%) or by an ophthalmologist (37, 24%). Two-thirds of the patients underwent TAB within seven days of referral. In 73, 47% of cases, the post-fixation biopsy sample size exceeded 10 mm. Positive biopsy results were found in 45 patients (29%). GCA was confirmed in 39% of patients with polymyalgia rheumatica (PMR), 24% with diabetics, 20% with hypothyroidism, 29% with hypertension, 32% with hyperlipidaemia,and 26% with other inflammatory diseases. However, the p-value was below the statistically significant threshold. The biopsy outcome was also not dependent on the speciality, time from referral to biopsy, nor on the length of the post-fixation specimen. Conclusions Temporal artery biopsy remains a valuable and crucial diagnostic tool in challenging equivocal cases of giant cell arteritis (GCA), although it is limited by its sensitivity, but there is also room for improvement. There is still uncertainty regarding the relationship between biopsy positivity, post-fixation sample size, and the interval between referral and procedure. Additionally, the speciality of the clinician performing the biopsy does not appear to significantly influence the likelihood of a positive result. We still do not fully understand why this is, but the association of the GCA with other comorbidities was unpredictably insignificant.

Interpreting Histopathology Reports of Temporal Artery Biopsies Positive for Giant Cell Arteritis (GCA): A Single-Center Retrospective Study.

The gold standard for diagnosing giant cell arteritis (GCA) is temporal artery biopsy (TAB). However, specific histopathologic findings on biopsy reports are rarely considered in the context of the patient's clinical presentation. The purpose of this study was to analyze the correlation of specific biopsy findings with the clinical presentation of patients with GCA. Retrospective chart review of patients with a clinical and histopathologic diagnosis of GCA at a single tertiary care neuro-ophthalmology practice from January 2014 to September 2023. Histopathologic findings on TAB were recorded for each patient, along with clinical history, examination, and treatment. Continuous variables were reported as mean values with standard deviations (SD), while categorical variables were described as percentages. Correlation coefficients with P-values were used to evaluate the relationship between biopsy findings and clinical data. A total of 53 patients were included. TAB specimens ranged in length from 0.6 to 3.4 cm, with a statistically significant correlation coefficient between specimen length and total number of positive findings on the biopsy report. A positive correlation coefficient that approached statistical significance was found between the presence of lymphocytes in the biopsy and permanent vision loss (R = 0.253, P-value 0.054), which occurred in 27 patients. Patients were treated with steroids prebiopsy for an average of 9 days; there was no statistically significant correlation between the duration of steroid treatment and the presence of specific histopathologic findings other than involvement of the intima. The results of this study demonstrate that (1) longer temporal artery biopsy specimens are significantly correlated with a higher number of findings on biopsy reports; (2) the presence of arterial stenosis, eosinophils, and lymphocytes correlated with permanent vision loss or degree of vision loss; and (3) the duration of steroid treatment had a significant inverse correlation with intimal involvement but did not affect other histopathologic findings seen with GCA. This retrospective observational study provides clinicians with an approach to understanding the nuances of the histopathologic findings on their patient's TAB report.

Self-limited giant cell arteritis: The dilemma associated with its diagnosis and treatment.

Giant cell arteritis (GCA) can result in visual loss and other sequelae. An 81-year-old man presented with a one-week history of fever. He had bilateral temporal headache, jaw claudication, tenderness of the temporal arteries and a recent skin rash. A temporal artery biopsy showed typical GCA, but the symptoms were self-limiting. We continued close observation, without administering prednisolone treatment. Five months later, the symptoms did not recur, and prednisolone again was not administered. Our patient presented with an atypical course of GCA that created a clinical dilemma. The final diagnosis was self-limiting GCA.

Risk factors and treatment window in arteritic anterior ischaemic optic neuropathy: a case study

A 76-year-old NZ European man presented with sudden onset visual loss in his left eye after experiencing intermittent temporal aches and blurry vision for over a month. He had a history of stroke and hyper- tension but no past ophthalmological history. A pale optic disc, raised inflammatory markers, and temporal artery biopsy confirmed a diag- nosis of acute arteritic anterior ischaemic optic neuropathy secondary to giant cell arteritis. High-dose intravenous methylprednisolone was administered within 24 hours of presentation, but the likelihood of vision loss reversal was unlikely.

Optical frequency domain imaging (OFDI) represents a novel technique for the diagnosis of giant cell arteritis.

Giant cell arteritis (GCA) is an inflammatory vascular disease in which prompt and accurate diagnosis is critical. The efficacy of temporal artery biopsy (TAB) is limited by 'skip' lesions and a delay in histological analysis. This first-in-man ex-vivo study aims to assess the accuracy of optical frequency domain imaging (OFDI) in diagnosing GCA. 29 TAB samples of patients with suspected GCA were submerged in 0.9% sodium chloride and an OFDI catheter was passed through the lumen to create cross-sectional images prior to histological analysis. The specimens were then preserved in formalin for histological examination. Mean intimal thickness (MIT) on OFDI was measured, and the presence of both multinucleate giant cells (MNGCs) and fragmentation of the internal elastic lamina (FIEL) was assessed and compared with histology, used as the diagnostic gold standard. MIT in patients with/without histological evidence of GCA was 0.425 mm (±0.43) and 0.13 mm (±0.06) respectively compared with 0.215 mm (±0.09) and 0.135 mm (±0.07) on OFDI. MIT measured by OFDI was significantly higher in patients with histologically diagnosed arteritis compared to those without (p = 0.0195). For detecting FIEL and MNGCs, OFDI had a sensitivity of 75% and 28.6% and a specificity of 100% and 77.3% respectively. Applying diagnostic criteria of MIT > 0.20 mm, or the presence of MNGCs or FIEL, the sensitivity of detecting histological arteritis using OFDI was 91.4% and the specificity 94.1%. OFDI provided rapid imaging of TAB specimens achieving a diagnostic accuracy comparable to histological examination. In-vivo imaging may allow imaging of a longer arterial section.

Signal Regulatory Protein α Expression in Systemic Vasculitis.

Signal regulatory protein α (SIRPα) is found primarily on myeloid cells, including macrophages and neutrophils; binds to CD47; and regulates phagocytosis, antigen presentation, cellular fusion, cell proliferation, and migration. Therefore, SIRPα may be involved in the pathogenesis of autoimmune diseases, including systemic vasculitis. This study aimed to assess SIRPα expression in tissue samples from patients with vasculitis. Immunohistochemical staining for SIRPα was performed on temporal artery (TA), kidney, and lung biopsy samples from patients with giant cell arteritis (GCA), patients with microscopic polyangiitis (MPA), patients with granulomatosis with polyangiitis (GPA), and patients without vasculitis. A score of SIRPα+ expression was calculated, derived from the percentages of monocytes, macrophages, and dendritic cells and neutrophils with different staining intensities in affected tissues. A total of 46 samples from patients with different vasculitides (GCA, MPA, and GPA) were included in the study. Tissue samples included TA samples from 15 patients with GCA; kidney samples from 11 and 9 patients with GPA and MPA, respectively; and lung samples from 11 patients with GPA. Most tissue samples from patients with active vasculitis (15 of 15 TA samples, 17 of 20 kidney samples, and 9 of 11 lung samples) showed SIRPα staining. SIRPα staining intensity was less in kidney samples compared to TA and lung samples. This study demonstrates high-level expression of SIRPα in macrophages and monocytes in affected tissue in systemic vasculitis. These findings provide a foundation for further studies exploring the role of the SIRPα-CD47 pathway in the pathogenesis of systemic vasculitis and the potential for the blockade of SIRPα and/or the depletion of SIRPα+ cells as treatment of systemic vasculitis.