DESCRIPTION
A 52-year-old female with systemic lupus erythematosus (SLE) and with arthritis, autoimmune hepatitis and polyserositis, was admitted with gradually worsening dyspnoea on exertion since her SLE diagnosis 2 years earlier. The patient was orthopnoeic and examination revealed paradoxical diaphragmatic movement with inspiration. Chest x ray showed bilateral elevated hemi-diaphragms and atelectasis at both lung bases (fig 1). Computed tomography (CT) imaging revealed profound low lung volumes with compressive atelectasis in the middle and lower lobes but no evidence of interstitial lung disease (fig 2). Comparison with a chest radiograph taken 2 years previously (fig 3) confirmed the progressive decline in lung volume. Plethysmography showed a restrictive lung pattern with a marked decrease in total lung capacity. The possibility of a skeletal myopathy or motor neuron disease was ruled out clinically. A diagnosis of shrinking lung syndrome (SLS) related to systemic lupus erythematosus (SLE) was made.
Figure 1.
Chest x ray at presentation (2008) showing reduced lung volumes.
Figure 2.
Chest CT (coronal) at presentation (2008) showing elevated hemi-diaphragms and unremarkable lung parenchyma.
Figure 3.
Chest x ray taken 2 years before presentation shows near normal lung volumes.
SLS, coined by Hoffbrand and Beck in 1965, is a rare pulmonary manifestation of SLE.1 The pathophysiology of SLS is unclear; a myopathic process affecting the diaphragm or intercostal muscles is thought to be the primary abnormality.2 Exercise intolerance over weeks to months is the common mode of presentation and is seen months to years after SLE is diagnosed. The respiratory dysfunction appears to be independent of the clinical course, duration and lupus antibodies (ANA and anti-DNA).3 Characteristic diagnostic findings include elevated diaphragms on imaging and restrictive lung volumes on pulmonary function tests.2 The absence of other pathological conditions is evidenced in most reports by normal V/Q scans, bronchoscopy and lung biopsies. Prognosis is generally good and most patients improve on increasing the dose of steroids aimed at the subclinical respiratory myositis-like process.3
Footnotes
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication.
REFERENCES
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