Pulmonary Manifestations of Systemic Lupus Erythematosus
typically presents as pleuritic chest pain accompanied by dyspnea, cough or fever in approximately 45–60 % of patients.7,12
Pleural effusions
have been reported in up to 50 % of patients with SLE-related pleuritis, and these effusions are usually bilateral, and equally distributed.2,7 Unilateral effusion should prompt one to consider an etiology other than active SLE, such as pulmonary embolus, malignancy, parapneumonic effusion, or empyema.
Some distinguishing features of SLE-related pleural effusions include pleural glucose concentration, pleural protein concentration, and pleural fluid white blood count (WBC). Pleural fluid glucose concentration is typically >70 mg/dl in SLE-related effusions and <20 mg/dl in effusions from rheumatoid arthritis (RA) or empyema. In one series, pleural glucose concentration was >70 mg/dl in most SLE-related effusions, and >56 mg/dl in all of them.53
Patients with SLE have many reasons other than lupus pleuritis to present with pleural effusions, and a thoracentesis is often indicated to clarify the diagnosis. Pleural fluid analysis may be warranted to exclude infection, malignancy, congestive heart failure, or other processes. Pleural fluid in SLE is typically a serous or serosanguinous exudate.52
These findings
were corroborated in another series in which pleural glucose concentration was >70 mg/dl in 12 of 14 patients with SLE-related pleural effusions.52
bodies that are engulfed by phagocytic cells.55
LE cells represent the remnants of apoptotic nuclear They may be found in
The presence of lupus erythematosus (LE) cells within pleural fluid is a highly specific finding in SLE-related pleuritis (see Figure 2).54
Other measurable features of pleural fluid are even less reliable in distinguishing SLE-related effusions from other causes. Low levels of complement, high levels of immune complexes, ANAs and rheumatoid factor have been regularly detected in both SLE- and non- SLE-related pleural effusions.56–58
Treatment of pleural disease is often guided by severity of symptoms. Non-steroidal anti-inflammatory drugs (NSAIDs) are often effective for symptomatic pleurisy, but may be contraindicated in patients with renal disease or on anticoagulation therapy. For these patients or those not responding to NSAIDs, moderate doses of systemic corticosteroids may be required (0.5 mg/kg prednisone or equivalent). In our experience, colchicine 0.6 mg up to twice daily can be quite effective for refractory SLE-related pleurisy (unpublished), echoing the utility of colchicine in recurrent pericarditis.59
However, refractory pleural effusions are rare
and only a few cases have been reported in the literature. In these cases, systemic immunosuppressive therapy is preferred to invasive procedures, such as chest tube drainage or pleurodesis.60
In patients with SLE, it can be difficult to distinguish the chest pain of pleuritis from common causes of chest wall pain such as costochondritis or fibromyalgia. However, patients with fibromyalgia generally have diffuse widespread tenderness not limited to the chest wall. While both pleuritis and costochondritis worsen in a recumbent position, the latter is distinguished by clearly reproducible pain on
US RESPIRATORY DISEASE
pleural fluid, pericardial fluid, ascities, or bone marrow in patients with SLE. Less distinguishing than pleural glucose or LE cells, but still of some clinical utility, are the observations that pleural fluid protein concentration and pleural WBC tend to be lower in SLE-related effusions compared with RA-related effusion, but a significant overlap exists.5
Figure 2: Lupus Erythematosus Cells (Arrows) in Pleural Fluid Exudate in a Patient with Systemic Lupus Erythematosus
direct palpation of tender areas. Treatment of chest wall pain includes local heat, NSAIDs, topical analgesics, and acetaminophen. Occasionally, local trigger point injections or steroids can be helpful in refractory cases.61
Shrinking Lung Syndrome
First described in 1965, shrinking lung syndrome is characterized by unilateral or bilateral diaphragmatic elevation on chest radiography.63
Thus, shrinking lung syndrome does not
Shrinking lung syndrome is a rare, somewhat nebulous entity in which SLE patients experience unexplained dyspnea, orthopnea and episodic pleuritic chest pain in association with reduced lung volume on chest imaging.62
However, chest CT imaging shows no disturbance of lung parenchyma, and PFTs demonstrate a restrictive pattern of lung disease with normal DLCO.62
appear to be a result of parenchymal or vascular lung disease, and several prevailing hypotheses exist about its etiology. Older studies reported that inspiratory pressures may be reduced in patients with shrinking lung syndrome, suggesting weakness of the diaphragm or other respiratory muscles.64,65 observed in other patients.66
Phrenic nerve dysfunction has been Additional mechanisms likely exist as well,
Other contributing factors likely include pleural inflammation, pleural adhesions, chest wall pain, and decreased chest wall compliance.62
as magnetic stimulation of the phrenic nerve has revealed normal conduction and diaphragmatic muscle strength that did not improve with therapy.67
Shrinking lung syndrome is a rare disorder, so optimal therapeutic modalities have not been established. Many classes of drugs have been suggested, including NSAIDs, moderate-to-high dose corticosteroids, and other immunosuppressive drugs (e.g. methotrexate, azathioprine, or cyclophosphamide). Diaphragmatic stimulators such as theophylline and β-agonist drugs may have a role as well.62
However, despite
intervention some patients progress on to respiratory failure. Conclusions
The pulmonary manifestations of SLE can be extremely varied in terms of clinical presentation, severity, and outcomes. This may make it
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