A previously healthy 22-year-old woman presents to the emergency department (ED) with acute shortness of breath. Her shortness of breath became worse with exertion and was associated with pleuritic chest pain for 2 days. She has had a fever, nonproductive cough, nausea, vomiting, and arthralgia.
On presentation, she is febrile with a temperature of 101.5°F (38.6°C), a blood pressure of 88/54 mm Hg, a pulse of 104 bpm, a respiratory rate of 28 breaths/min, and an oxygen saturation of 88% while breathing room air. Her oxygen saturation improved to 92% with supplemental oxygen given at 2 L/min. She is in moderate respiratory distress; however, she can speak in full sentences. Her physical examination reveals absent breath sounds throughout the right thorax, with decreased breath sounds halfway up the left thorax. Other findings include egophony, decreased fremitus, and dullness to percussion on the right thorax. She has no jugular venous distention, edema on her lower extremity, or rash.
{mosimage}What is the diagnosis?
HINT
The pleural fluid was positive for lupus anticoagulant, anticardiolipin antibodies, anti–double-stranded DNA (1:40), and antinuclear antibodies (1:10,000).
Authors:
John Cho, MD, Pulmonary Critical Care Fellow, Department of Pulmonary and Critical Care, Cedars Sinai Medical Center, Los Angeles, CA
Rick G. Kulkarni, MD, Assistant Professor, Yale School of Medicine, Section of Emergency Medicine, Department of Surgery, Attending Physician, Medical Director, Department of Emergency Services, Yale-New Haven Hospital, Conn
eMedicine Editors:
Sat Sharma, MD, Associate Professor, University of Manitoba, Department of Internal Medicine, Divisions of Pulmonary and Critical Care Medicine.
Rick G. Kulkarni, MD, Assistant Professor, Yale School of Medicine, Section of Emergency Medicine, Department of Surgery, Attending Physician, Medical Director, Department of Emergency Services, Yale-New Haven Hospital, Conn
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Lupus pneumonitis: The chest radiograph (see Image 1) reveals a small pleural effusion on the left side, one quarter of the way up; in addition, a right-sided pleural effusion with mediastinal shift to the left can be seen. The patient was admitted to the intensive care unit (ICU) because of acute respiratory distress. A contrast-enhanced computed tomography (CT) scan (see Image 2) of the chest confirmed the right-sided pleural effusion, small left-sided effusion, and pulmonary infiltrates.
A thoracentesis was performed, and the samples were negative for infection on cultures and Gram staining. A pleural cytology examination was performed and was noted to be unremarkable for malignant or atypical cells. Lactate dehydrogenase (LDH) was greater than 200 U, with a fluid-to-blood ratio of 0.75. Protein levels were increased as well, with a fluid-to-blood ratio of 0.6. The patient was found to have an exudative process. In 1972, Light and colleagues described criteria for differentiating a transudate from an exudate: if LDH is more than 200 U, the fluid-to-blood LDH ratio is more than 0.6, or the fluid-to-blood protein ratio is more than 0.5, there is a 99% positive predictive value for an exudate with a corresponding 98% negative predictive value.1 Additionally, as previously noted, the pleural fluid was positive for lupus anticoagulant, anticardiolipin antibodies, anti–double-stranded DNA (1:40), and antinuclear antibodies (1:10,000).
Given the results of the patient's pleural fluid analysis, the diagnosis of systemic lupus erythematosus (SLE) presenting with acute pneumonitis was made. The patient's condition improved with intravenous Solu-Medrol, and she was discharged to home several days later with a prescription for oral prednisone.
SLE is a chronic multisystemic microvascular inflammatory disease. In the United States, the incidence of SLE is 1 case per 2000 population, with an increased prevalence in women of childbearing age and in certain ethnic groups (eg, African Americans, some Polynesian groups).
The pulmonary manifestations of SLE include both acute and chronic processes. Acute complications include pulmonary embolus, pneumonia, diffuse alveolar hemorrhage, and lupus pneumonitis. The diagnosis in this case, acute lupus pneumonitis, is an uncommon presentation that accounts for as many as 10% of all lupus cases. The symptoms of lupus pneumonitis are severe dyspnea, tachypnea, fever, pleurisy, cough, basilar rales, and hypoxia. Patients have no apparent infection. Radiographs usually show atelectasis and infiltrates, predominantly in the lower lobes. Additionally, up to 30% of patients have pleural effusion. Pathologically, findings of diffuse alveolar damage are seen in patients with lupus pneumonitis.
Lupus pneumonitis usually responds to glucocorticoids. Intravenous pulse steroid therapy or immunosuppressive drugs may be considered if patients do not improve in 3 days. Lupus pneumonitis may progress to pulmonary fibrosis and, eventually, pulmonary hypertension. If left untreated, the prognosis of patients with lupus pneumonitis is poor, with short-term mortality rates approaching 50%.
References
Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr. Pleural effusions: the diagnostic separation of transudates and exudates. Ann Intern Med. 1972 Oct;77(4):507-13. [MEDLINE: 4642731]
McEwen JI. Pleural Disease. In: Rosen P, Barkin R, Danzl D, Hockberger R, Ling L, Markovchick V, et al, eds. Emergency Medicine: Concepts and Clinical Practice. 4th ed. New York, NY: Mosby; 1998:1511-28.
