Systemic Lupus Erythematosus and Shrinking Lung Syndrome

Shrunken lung syndrome (SLS), also known as vanishing lung syndrome, is a rare manifestation of several autoimmune diseases, including SLE. 

Presentation

SLS should be suspected in patients who have dyspnea or restrictive lung physiology on pulmonary function tests in the absence of radiographic evidence for interstitial lung disease.1,2 Symptomatic orthopnea may be noted secondary to diagphragmatic weakness.2

Diagnosis

Findings on chest radiographs may include elevated hemidiaphragms, pleural effusions, or pleural thickening. Thoracic CT scanning typically shows no evidence of parenchymal lung disease, although pleural effusions, pleural thickening, or atelectasis can sometimes be seen.

Pathogenesis

Conflicting results have been found concerning the underlying pathogenesis of this disorder. Several hypotheses have been suggested, including atelectasis resulting from the loss of surfactant, diaphgragmatic myositis or myopathy, phrenic nerve neuropathy, pleural adhesions, and diaphragmatic inactivation induced by pain.3

Treatment

There is no standard or universally agreed upon treatment strategy for SLS. The variety of treatments relates to uncertainty of its cause, and several investigators describe different approaches with beneficial results.

Glucocorticoids are generally considered first line therapy3, alone or in combination with other immunosuppressive agents. Theophylline and  beta-2 agonists have also been used in attempt to augment diaphragmatic strength.3

Rituximab is a chimeric mouse/human monoclonal antibody that specifically binds to the CD20 antigen expressed on pre-B and mature B lymphocytes, and has been shown in limited studies to be effective at treating SLS in SLE.4

Differential Diagnosis

SLS must be differentiation from other causes of diaphragmatic weakness or paralysis, as well as other causes of pleuritic pain accompanied by dyspnea including pulmonary embolism.2,3

Prognosis

The long-term prognosis of SLS in SLE is generally good. Deterioration requiring aggressive therapy or mechanical ventilation is relatively uncommon.4


References

1.       Karim MY, Miranda LC, Tench CM, et al. Presentation and prognosis of the shrinking lung syndrome in systemic lupus erythematosus. Semin Arthritis Rheum. 2002;31(5):289-298; doi: 10.1053/sarh.2002.32555

2.       Warrington KJ, Moder KG, Brutinel WM. The shrinking lungs syndrome in systemic lupus erythematosus. Mayo Clin Proc. 2000;75(5):467-472; doi: 10.4065/75.5.467

3.       Mittoo S, Fell CD. Pulmonary manifestations of systemic lupus erythematosus. Semin Respir Crit Care Med. 2014;35(2):249-54.

4.      Benham H, Garske L, Vecchio P, Eckert BW. Successful treatment of shrinking lung syndrome with rituximab in a patient with systemic lupus erythematosus. J Clin Rheumatol. 2010;16(2):68-70; doi: 10.1097/RHU.0b013e3181d0757f