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The lungs in the rheumatic diseases.

There are many different approaches to the evaluation of the lungs in patients with collagen vascular diseases. Many books have been published about the evaluation of the lungs in patients with rheumatic diseases (connective tissue diseases (CTDs) and rheumatoid arthritis (RA)). Unfortunately, it still remains a challenging task - even for a pulmonologist. As with all medical conditions, there is no substitute for a thorough history and careful examination of the patient. Although significant heterogeneity exists among the different collagen vascular diseases, they share one aspect that is common to their pathogenesis: circulating auto-antibodies and immunemediated organ dysfunction.

There are several tools to evaluate the lungs of patients with a CTD. Currently none is as valuable as the chest radiograph as an initial screening tool to exclude major pathology. If pathology is identified, a high-resolution computerised tomography (HRCT) scan of the chest is performed to confirm the pathology and ascertain a possible aetiology (1), (2), (3) The most important rheumatic diseases that affect the lungs include:

* RA

* systemic lupus erythematosus (SLE)

* systemic sclerosis

* Sjogren's syndrome

* polymyositis /dermatomyositis /antisynthetase syndromes

* mixed CTDs

* primary vasculitic syndromes (e.g. Wegener's granulomatosis).

When evaluating the lungs of patients with a CTD several different aspects of the disease process need to be considered before the clinician can come up with an appropriate differential diagnosis. The most important questions the treating clinician (general practitioner, general physician, rheumatologist or pulmonologist) has to consider include

* Has the patient's CTD been well characterised clinically, serologically and radiologically?

* Is the collagen vascular disease well established and is the patient on appropriate therapy?

* Is there a super-added infective aetiology (i.e. viral, fungal, bacterial or mycobacterium)?

* Is there a possibility of drug toxicity (i.e. methotrexate (MTX) lung toxicity, salazopyrine toxicity or disease related to biological agents)?

* Has the patient developed an unrelated separate pathology (i.e. hypersensitivity pneumonitis, a secondary malignancy or an aspiration pneumonitis)? (4), (5)

With the above possibilities in mind, Table I highlights the most common diseaseassociated (CTD) pulmonary manifestations.

The ILDs pose the greatest diagnostic challenge and therapeutic dilemma. There are various different histological sub-classifications of the ILDs, but the most important include:

* UIP = usual interstitial pneumonia (formerly called CFA= cryptogenic fibrosing alveolitis)

* NSIP = nonspecific interstitial pneumonitis

* OP = organising pneumonia (formerly called BOOP= bronchiolitis obliterans organising pneumonia)

* LIP = lymphocytic interstitial pneumonia.

NSIP is the most common histological pattern associated with a CTD. However, in RA a UIP pattern is more common, while in Sjoren's syndrome LIP is the predominant histological pattern. Furthermore, patients with scleroderma are particularly prone to developing pulmonary vascular hypertension
Table I. Major pulmonary manifiestations of the rheumatic diseases

          Systemic   Rheumatoid arthritis  Sjogren's syndrome
          sclerosis

Airways   -          ++                    ++
ILD       +++        ++                    ++
Pleural              ++                    +
Vascular  +++
DAH                  -

          Mixed CTDs  Polymyositis / dermatomyostis  SLE

Airways   +           -                              +
ILD       ++          +++                            +
Pleural   +                                          +++
Vascular  ++          +                              +
DAH                                                  ++

ILD = interstitial lung disease; DAH = diffuse alvsolar haemorrhage.


This could be as a result of the vasculopathy associated with the scleroderma, vascular hyper-reactivity associated with Raynaud's phenomenon, hypoxia due to an ILD or pulmonary thrombo-embolic disease. Unfortunately, the pulmonary hypertension carries with it a grave prognosis for the patient and needs to be specifically evaluated for. Pulmonary thrombo-embolic disease (PTED) might also be a complicating feature of the anti-phospholipid syndrome.(6)

When a patient with a CTD-associated ILD is being evaluated, the following initial questions need to be answered before an accurate diagnosis can be made:

* Does the patient have a well-characterised CTD, and if so:

* Does the ILD pattern fit with the CTD? Alternatively, is there a separate pathology, i.e. infection or drug toxicity?

* If the patient does not have a known CTD:

* Are there extra-thoracic features of a CTD?

* Is this the pulmonary manifestations of a forme fruste CTD? (4), (5)

The aspects that are paramount to establishing a diagnosis of a rheumatic disease include:

* good skin examination

* good joint examination

* nailfold capillaroscopy

* ANA, RF, CPK, aldolase

* If ANA+, then do extractable nuclear Ag panel

* If [up arrow] CPK/aldolase or ANA+ then do myositis-specific Ab panel including anti-Jo 1

* If +RF, then do anti-CCP as well as hand/foot X-rays.

Of note when evaluating CTD-associated ILD:

* The ILD may be the first or lone manifestation of a CTD.

The extra-thoracic manifestations of an underlying CTD may be subtle and must be assessed for.

* ANA and RF are poor screening tests, especially when considering the anti-synthetase syndromes, Sjogren's syndrome and the mixed CTDs because the ANA/RF might be negative in these conditions.

Once the diagnosis of a CTD-associated ILDhas been established based on history and clinical examination, a useful approach to the plain radiograph is to use the following anatomic acronym when viewing the chest X-ray: PAINT

When a diagnosis of a CTD-associated ILD is strongly suspected on the plain radiograph, a HRCT scan will provide the necessary clarification as to the particular anatomical regions involved. Important clues to the presence of a CTD-associated ILD include the presence of a dilated oesophagus, pericardial thickening with effusion and presence of bilateral, bibasilar and predominantly peripheral changes. When evaluating the lung parenchyma, particular attention should be paid to the predominant pattern of lung involvement. Table II highlights the most common HRCT chest patterns associated with the rheumatic diseases. (2), (3)

Table II. The most common HRCT chest patterns associated with the rheumatic diseases

Nodular involvement

Infection

Alveolitis

Capillaritis

Granulomatous infiltrates

Interstitial

Atypical infections

Viral pneumonitis

Drug reaction

Idiopathic interstitial pnuemonia (UIP v. NSIP)

Cystic

Lymphocytic interstitial pneumonias

Pneumocystis pneumonia

Necrotising infection

Ground glass

Active alveolitis

Diffuse air trapping with bronchiolitis

Variable perfusion with PTED

Air bronchiograms

Infection

BOOP

UIP = usual interstitial pneumonia; NSIP = nonspecific interstitial pneumonia; PTED = pulmonary thrombo-embolic disease; BOOP = bronchiolitis obliterans organising pneumonia.

After the disease process has been assessed anatomically with the HRCT scan, the impact of the disease on the patient's health has to be physiologically quantified. This is achieved by means of a full lung functio test. The important parameters measured include the lung volumes (vital capacity (VC) and total lung capacity (TLC) and the diffusion co-efficient (DLCO). (5)

The lung volumes are:

Increased (obstructive lung functions) with pathologies that lead to air trapping, i.e. airway hyper-reactivity (asthma), bronchiectasis and bronchiolitis obliterans or reduced (restrictive lung function) with pathologies that involve the lung parenchyma (ILD), the pleura or the thoracic cage.

The DLCO is decreased with pathologies that involve the lung parenchyma (ILD) or increased with pulmonary haemorrhage syndromes (Table III).
Table III. The pulmonary function test abnormalities commonly
encountered in CTD

                 Lung volumes                  DLCO

Increased  Asthma, emphysema,         Pulmonary haemorrhage
           bronchiectasis and         syndromes,
           bronchiolitis obliterans   polycythaemia

Decreased  Interstitial pneumonia     Interstitial pneumonia
           (ILD)                      (ILD)
           BOOP                       PTED
           Pleural and thoracic cage
           disease


An additional important, yet simple and non-invasive, tool for monitoring CTDassociated ILD and the response to therapy is the determination of the 6-minute walk test, which is an objective assessment of effort tolerance. A slightly more invasive tool that also provides a wealth of information is bronchoscopy and bronchiolar lavage. It has the potential to exclude infection and ascertain the cellular nature of the alveolar filling process (i.e. blood, pus, fluid or cells). Furthermore, if there are no contraindications a transbronchial biopsy may be done to obtain a histological diagnosis.

In conclusion, a few words on methotrexate pneumonitis as it is the perennial question aced by all physicians treating rheumatic isease patients on methotrexate:

* ccurs a few days to weeks after initiation of therapy

* not dose dependent

* major symptoms include dyspnoea, nonproductive cough, fever

* eosinophilia present in > 50% of patients

* CXR features include difffuse alveolar infiltrate hilar adenopathy pleural effusions (10 - 15%)

* form of hypersensitivity pneumonitis with eakly formed granulomas

* Can re-challenge patients if the response to drug withdrawal is good. (7)

Summary

* The lungs are often affected by all the rheumatic diseases.

* The pathology in the lungs is multifactorial and involves different parts of the lung parenchyma.

* The main differential diagnosis includes disease progression, infection and drug toxicities.

* Special investigations such as a HRCT scan of the chest are often needed to determine the possible aetiology.

* Using an algorithm-based approach to the interpretation of the chest X-ray assists in narrowing the differential diagnosis.

* Lung function tests often aid in excluding the interstitial process from predominant airway diseases.

* A thorough musculoskeletal examination including particular attention to nail-fold capillaroscopy and the skin for specific rashes is invaluable.

* A multidisciplinary approach to total patient care improves patient outcomes.

P = Pleural space

Pleural effusion/pericardial effusions

Pleural thickening

A= Airways and alveolar spaces

Airways: large airways for airway hyper-reactivity or scarring from bronchiectasis, smaller airways for air-trapping and bronchiolitis obliterans

Alveolar spaces: for consolidation identified by air bronchiograms implying an alveolar filling process by either blood, pus, fluid or cells

I= Interstitium

The connective tissue network supporting the capillary bed is identified by reticular infiltrates and honey-comb changes. Particular attention needs to be paid to the zone of the lung involved, as ankylosing spondylitis has a preponderance to involve the apices and RA the bases

Vascular bed involvement, including looking for pulmonary arterial or venous hypertension Nodular infiltrates for an active capil-laritis or alveolitis

N= Neuromuscular

Peripheral nerve disease identified by phrenic nerve involvement

Muscular involvement identified by vanishing lung syndrome associated with small lung fields and diaphragmatic elevations

T= Thoracic skeleton

Evidence of vertebral collapse sternal head erosions and costochondritis

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References available at www.cmej.org.za

ISMAIL S KALLA, MB BCh, FCP (SA), FCCP (USA), Cert Pulmonology (SA), Cert Critical Care (SA)

Pulmonologist/intensivist, DepartmentofPulmonologyandCriticalCare, UniversityoftheWitwatersrand, Johannesburg

Correspondence to: I S Kalla (isk786@telkomsa.net)
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Title Annotation:MORE ABOUT...RHEUMATOLOGY
Author:Kalla, Ismail S.
Publication:CME: Your SA Journal of CPD
Article Type:Report
Date:Aug 1, 2011
Words:1706
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