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Pulmonary manifestations of scleroderma

Dr Elena Trajcevska and Dr Natalie Yang et al.

Pulmonary manifestations of scleroderma are demonstrated histologically in 90% of patients with scleroderma. It is a leading cause of mortality and at autopsy, the lung is reportedly involved in close to 100% of cases. However, only 25% of patients will present with respiratory symptoms or demonstrate abnormalities on CT ⁴.

For a discussion of scleroderma in general, please refer to parent article : scleroderma.

Pathology

The pathogenesis of pulmonary involvement relates to to separate mechanisms :

usual interstitial pneumonia (UIP) : histologically indistinguishable from rheumatoid lung and idiopathic pulmonary fibrosis (IPF)
secondary lung injury due to aspiration pneumonitits secondary to oesophageal involvement : see gastrointestinal manifestations of scleroderma

The two pathologies may co-exist. The remainder of the article discusses the former. Please refer to aspiration pneumonitis for discussion of that entity.

Clinical presentation

In patients who are symptomatic due to pulmonary involvement, respiratory function tests typically demonstrate a restriction pattern, consisting of ⁴:

diminished lung volumes
preserved flow rates
low diffusion capacity

Radiographic features

Plain film

Chest radiographs are insensitive to early changes, and may appear normal despite respiratory function test abnormalities. Eventually, changes of pulmonary fibrosis become evident. Additional features include ⁴:

dilated oesophagus
eggshell calcification of mediastinal nodes
pleural effusions are uncommon
enlargement of cardiac silhouette and pulmonary arteries due to scleroderma induced pulmonary vascular disease may also be evident.

HRCT

On HRCT, scleroderma may appear in a usual interstitial pneumonitis (UIP) or non specific interstitial pneumonitis (NSIP) pattern. Interstitial lung changes in scleroderma are generally less extensive and less coarse than those with idiopathic pulmonary fibrosis (IPF) ³ with most patients only show a limited portion of lung involvement (less than 10% in half of cases) ¹.

early stages may show ground glass changes
later stages may show honeycombing and evidence of lung volume loss
lung bases and sub-pleural regions typically involved ⁴
cysts may be present measuring 1 - 5cm in diameter ⁴
pleural effusions are usually not a feature

A dilated oesophagus is not an uncommon finding.

Treatment and prognosis

Pulmonary involvement is incurable but a number of compounds may improve or halt progression. These include cyclophosphamide, glucocorticoids or N-acetylcysteine, although the data is inconclusive ⁵.

Complications include:

pulmonary arterial hypertension is seen in up to 50% of patients, and may develop without evidence of interstitial fibrosis ^2,4
higher incidence of lung cancer, particularly bronchoalveolar carcinoma ⁴
rupture of pulmonary cysts resulting in a pneumothorax ⁴

The cause of death is often from an aspiration pneumonia.

Differential diagnosis

On HRCT the differential is essentially that of usual interstitial pneumonia and lower zone pulmonary fibrosis.

A helpful clue to the diagnosis on CT is the presence of a dilated oesophagus.
Pleural effusions are distinctly uncommon in scleroderma, and would favour the diagnosis or either rheumatoid lung or SLE ⁴.