1. Anti-neutrophil cytoplasmic

autoantibodies

2. What diagnostic tests should

be performed in patients

clinically suspected of

pulmonary vasculitis that are

ANCA negative?

3. Conclusion

Editorial

What to do when you suspectyour patient suffers frompulmonary vasculitis?Jan Willem Cohen TervaertMaastricht University, Maastricht, The Netherlands

Making a diagnosis of pulmonary vasculitis is challenging. The most common

cause of pulmonary vasculitis is small vessel anti-neutrophil cytoplasmic

antibody (ANCA)-associated vasculitis. Pulmonary involvement in other forms

of vasculitis such as large vessel vasculitis is rare. Since correct and timely

diagnosis is pivotal to start (immunosuppressive) therapy to avoid vasculitic

damage, a complete patient history should be obtained and a physical exam-

ination performed. Initial laboratory evaluation should include inflammation

markers, renal and liver function tests, and the determination of ANCA. New

developments in ANCA testing result in tests with excellent predictive value

for the diagnosis of AAV-related pulmonary vasculitis. Consequently, ANCA

should be tested with these tests of the so-called second (capture ELISA) or

third (anchor ELISA) generation. In patients who are ANCA negative, a simple

algorithm is presented based on laboratory evaluation of autoantibodies and

18F-FDG-PET-CT scanning. Such an algorithm may be useful for accelerating

the diagnostic process needed to make a diagnosis of pulmonary vasculitis,

or alternatively, to quickly exclude such a diagnosis.

Keywords: 18F-FDG-PET-CT scanning, cryoglobulins, MPO-ANCA, PR3-ANCA, pulmonary

vasculitis

Expert Opin. Med. Diagn. (2013) 7(1):1-4

The clinical approach to a patient with possibly pulmonary vasculitis depends on asmart clinician who is astute enough to consider the diagnosis and who is capable toidentify the clinical, radiological, laboratory, and pathological abnormalities. In theNovember 2012 issue of Expert Opinion on Medical Diagnostics, Casian and Jaynereview their extensive experience in order to provide readers of the Journal to obtainthe knowledge to act when pulmonary vasculitis is clinically suspected [1]. Althoughdiagnosis, generally, requires integration of clinical, laboratory, imaging (CT scan,MRI), lung functional, bronchoscopic and histological findings [1], a simplealgorithm (Figure 1) with a central role for laboratory evaluations is in my opinionvery helpful in guiding the diagnostic process. This algorithm is the main focus ofthis Editorial.

Pulmonary vasculitismainly occurs in patients with small vessel vasculitides (SVV).Patients with SVV often present with non-specific complaints such as malaise, fever,weight loss, fatigue, anorexia, and arthralgias. In addition, since the vasculitic processcan affect blood vessels in any location dysfunction in virtually any organ system canbe present. Pulmonary manifestations such as an antibiotic resistant pneumonia, anew-onset asthma, or alveolar lung hemorrhage should alert the physician to thepossibility of SVV [1]. Otherwise, pulmonary artery stenoses and/or aneurysms shouldalert the physician to the possibility of large vessel vasculitis.

Firstly, the clinician should perform laboratory testing including ESR,C-reactive protein, hemoglobulin, leukocyte and eosinophil count, serum creatinin

10.1517/17530059.2013.739604 © 2013 Informa UK, Ltd. ISSN 1753-0059, e-ISSN 1753-0067 1All rights reserved: reproduction in whole or in part not permitted

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level, transaminases, and urine investigations for the presenceof erythrocyturia and proteinuria [2]. In addition, patientsshould be tested for anti-neutrophil cytoplasmic autoantibodies(ANCA) (Figure 1).

1. Anti-neutrophil cytoplasmic autoantibodies

SVV can be classified as ANCA-associated vasculitis (AAV) ornon-ANCA associated SVV.Whereas pulmonary involvement

Clinical suspicion of pulmonary vasculitis orsystemic small vessel vasculitis

Test for ANCA

PR3-ANCA

AAV EGPA

Cryoglobulin-associatedvasculitis

Anti-GBM

CTD-associatedvasculitis

No classifyingdiagnosis

PET-CT

Large-vesselvasculitis

Limited GPA

pos pos neg

No classifyingdiagnosis

MPO-ANCA

Anti-GBM negative,negative blood

cultures

Eosinophilia /broncho-obstructive

disease

Test forcryoglobulins,Anti-GBM,ANA, Anti-CCP,lgM-RF, complement

ANCA-negative

Figure 1. Algorithm for the diagnostic process when evaluating a patient clinically suspected for pulmonary vasculitis. Firstly,

the patient is evaluated for the presence of anti-neutrophil cytoplasmic antibodies (ANCA). If ANCA directed to proteinase

3 (PR3-ANCA) or ANCA directed to myeloperoxidase (MPO-ANCA) are present, a test for the presence of anti-

glomerular basement membrane (GBM) antibodies should be performed to exclude anti-GBM disease. In addition, blood

cultures shouldbeobtained toexcludeendocarditis. If botharenegative,adiagnosisofANCA-associatedvasculitis (AAV) is likely.

If ANCA are not found, lung function tests should be performed to evaluate the presence of bronchusobstructive lung disease/

asthma. If present in combinationwith eosinophilia a diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) is likely.

If asthma and eosinophilia are absent, tests for cryoglobulins, anti-GBM antibodies, anti-nuclear antibodies (ANA), anti-

cyclic citrullinated peptide (anti-CCP), rheumatoid factor (IgM-RF), and complement shouldbe performed. If after these tests are

performednoclassifyingdiagnosis ismade,18F-FDG-PETCT scancanbethenext step.The18F-FDG-PETCT scanmayrevealuptake

in largevessels suggesting large vessel vasculitis. In addition, uptake in theupper/lower respiratory tract is suggestiveof localized

granulomatosis with polyangiitis (GPA) when other disorders (such as tuberculosis and lymphoma; see text) can be excluded.

J. W. C. Tervaert

2 Expert Opin. Med. Diagn. (2013) 7(1)

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in non-ANCA associated vasculitis is rare (less than 5% ofpatients), most attention should go to making a diagnosis ofAAV. ANCA in AAV recognize two different antigens,proteinase 3 (PR3) or myeloperoxidase (MPO) [3].TheAAV syndromes comprise granulomatosis with polyangiitis(GPA, Wegener’s), eosinophilic granulomatosis with polyan-giitis (EGPA; Churg-Strauss syndrome), and microscopicpolyangiitis (MPA). For classification of patients, however,we have proposed that ANCA serotype, that is, eitherMPO-ANCA or PR3-ANCA, is more important than classi-fying patients according to their clinical subtype, that is,GPA, EGPA, or MPA [3,4]. This proposal is supported bygenetic findings, clinical manifestations, and response totherapy which are all more related to ANCA serotype thanto clinical subtype [3-5].

So, the next step for the patient clinically suspected ofpulmonary vasculitis is testing the serum for the presence ofMPO-ANCA and PR3-ANCA. Since this testing is crucialfor the further diagnostic and therapeutic process, the qualityof ANCA testing should be optimal. ANCA are traditionallydetected by an indirect immunofluorescence (IIF) technique.In patients with AAV, either a cytoplasmic (C-ANCA;due to PR3-ANCA) or a perinuclear (P-ANCA; due toMPO-ANCA) staining pattern is observed. According to theinternational consensus on ANCA testing, ANCA should betested both by an IIF test and subsequently by antigen-specific tests [6]. During the last decade, the quality of theseantigen-specific tests improved substantially. Antigen-specifictests of the first generation (so-called “direct” enzyme-linkedimmunosorbent assays = ELISAs) can now be replaced by supe-rior assays of the second (i.e., capture ELISA) [3,7] or third (i.e.,anchor ELISA) [3,8] generation. Based on the results obtainedwith these newer ANCA test systems, we proposed that theseANCA tests of the second or third generation replace the needto perform IIF assays for ANCA detection [3].

In patients with MPA, generalized GPA or limited (“earlygeneralized”) GPA, virtually all patients have either PR3 orMPO-ANCA [3,9]. In patients with loco-regional GPA,however, ANCA is clearly not detected in all patients [3,10].In addition, in EGPA most patients are ANCA negativewhereas in about 40% of the patients MPO-ANCA can bedetected [3,11]. Although MPO-ANCA and PR3-ANCAwhen tested with these new ANCA assays are highly specificfor either GPA, EGPA, and/or MPA, it must be stressedthat these ANCA serotypes are also found in patients withanti-GBM disease or endocarditis with or without a compli-cating vasculitis [3]. Also, MPO-ANCA and/or PR3-ANCAcan be found during cocaine use and/or use of certain drugssuch as propylthiouracil [3].

If a patient is both clinically suspected of pulmonary vascu-litis and ANCA positive, a histological confirmation isfrequently sought but not invariably needed to make the diag-nosis of AAV. Preferred biopsy spots are affected organs suchas skin, nose, and/or kidney. An open lung biopsy is onlyneeded in extremely rare occasions [12].

2. What diagnostic tests should be performedin patients clinically suspected of pulmonaryvasculitis that are ANCA negative?

If a patient clinically suspected of pulmonary vasculitis doesnot test positive for ANCA, he/she may suffer from EGPA,cryoglobulin-associated vasculitis, anti-glomerular basementmembrane (GBM) disease, vasculitis secondary to connectivetissue diseases, localized GPA, or (occasionally) one of theother forms of vasculitis such as large vessel vasculitis, HenochSchonlein purpura, Behcet disease, or a secondary form ofvasculitis (Figure 1) [1,12].

These patients should undergo lung function tests to evalu-ate the presence of bronchusobstructive lung disease/asthma.If present in combination with eosinophilia, a diagnosis ofEGPA is likely and special attention should be paid to theperipheral nervous system (is polyneuropathy or mononeuritismultiplex present?), to the skin (are purpura or Churg-Straussnodules present?), and to cardiac involvement [2,11].

If eosinophilia and asthma are absent, the following labora-tory evaluations should be performed: cryoglobulins, comple-ment levels, rheumatoid factor IgM (IgM-Rf), anti-cycliccitrullinated peptide (anti-CCP) antibodies, anti nuclear anti-bodies, and anti-GBM antibodies. Special attention shouldbe paid to the detection of cryoglobulins. Since testing of theseantibodies is very sensitive to cooling, we perform this test withpreheated tubes. Furthermore, the tubes are kept at 37�Cduring transport to the laboratory to prevent cryoprecipitationprior to arriving in the laboratory [13]. When these measures arenot taken, the presence of cryoglobulins can be missed butsuspected by the presence of low levels of complement incombination with high levels of IgM-Rf in the absence ofanti-CCP antibodies.

When these laboratory evaluations are not helpful formaking a diagnosis, the patient clinically suspected of pulmo-nary vasculitis may still suffer from localized GPA, large vesselvasculitides, and/or other forms of vasculitis. In these cases, a18F-FDG-PET-CT scan can be the next step (Figure 1). The18F-FDG-PET-CT scanning has been used successfully formaking a diagnosis of large vessel vasculitis [1]. In addition,we found more recently that this technique is also useful fordiagnosing active SSV and a negative 18F-FDG-PET-CTscan virtually excludes active pulmonary vasculitis [14].Besides, the extent of (sometimes unsuspected) [15] organinvolvement can be ascertained using this technique.A positive 18F-FDG-PET-CT scan is, however, not a specificfinding and other diagnoses such as malignancy and tuberculo-sis still should be excluded. Therefore, in a patient clinically sus-pected of localized pulmonary GPA histological confirmationof vasculitis is mandatory.

3. Conclusion

Making a diagnosis of pulmonary vasculitis is challenging.Since correct and timely diagnosis is pivotal to start

What to do when you suspect your patient suffers from pulmonary vasculitis?

Expert Opin. Med. Diagn. (2013) 7(1) 3

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(immunosuppressive) therapy to avoid vasculitic damage,a complete patient history should be obtained and aphysical examination performed. Initial laboratory evalua-tion should include inflammation markers, renal and liverfunction tests and the determination of ANCA. Newdevelopments in ANCA testing result in tests with excellentpredictive value for the diagnosis of AAV-related pulmonaryvasculitis. Consequently, ANCA should be tested withthese tests of the so-called second or third generation. Inpatients who are ANCA negative, a simple algorithm ispresented based on laboratory evaluation of autoantibodiesand 18F-FDG-PET-CT scanning. Such an algorithm maybe useful for accelerating the diagnostic process needed to

make a diagnosis of pulmonary vasculitis, or alternatively,to quickly exclude such a diagnosis.

Acknowledgment

The author would like to thank B Wilde, MD, Department ofImmunology,MaastrichtUniversity,Maastricht, theNetherlandsfor help with making the figure.

Declaration of interest

The author states no conflict of interest and have received nopayment in preparation of this manuscript.

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AffiliationJan Willem Cohen Tervaert MD PhD

Professor of Medicine and Immunology,

Maastricht University, Maastricht,

The Netherlands

Tel: +31 43 3876543;

Fax: +31 43 3881436;

E-mail: jw.cohentervaert@maastrichtuniversity.nl

J. W. C. Tervaert

4 Expert Opin. Med. Diagn. (2013) 7(1)

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