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A 51-year-old woman was admitted to the hospital after 5 days of fever, cough, minor greenish sputum and right pleuritic pain. A non-smoker, she had a history of non-insulin-dependent diabetes and Sjögren's syndrome. Her temperature was 39ºC and her blood pressure was 160/75 mmHg. Pulmonary auscultation revealed right rales. The physical examination was otherwise unremarkable.
The white blood cell count was 12 930 × 109/l (88% neutrophils, 10% bands and 2% lymphocytes). The haemoglobin level was 8.8 g/dl and the erythrocyte sedimentation rate was 118 mm. The PaO2 when the patient was breathing ambient air was 63 mmHg. A Gram stain of the sputum revealed Gram-positive cocci. Three blood cultures obtained on admission yieldedStreptococcus pneumoniae. The isolate was characterised as serotype 35. A chest X-ray taken on admission disclosed a parenchymal infiltrate in the right lower lobe (figure 1). A X-ray taken 14 days later displayed a cavity with an air crescent sign. A computed tomography (CT) scan showed lung tissue within the cavity (figure2).
- What is the diagnosis?
- What pulmonary alterations are associated with Sjögren's syndrome?
- What is the management?
The diagnosis is pneumococcal pneumonia complicated by pulmonary gangrene. Although a definitive diagnosis of pulmonary gangrene requires pathological confirmation, the radiologic findings are typical. The presence of a fluid-filled cavity in which irregular pieces of sloughed lung parenchyma float like icebergs is virtually diagnostic
The pulmonary abnormalities associated with Sjögren's syndrome are listed in the box.
Pulmonary alterations associated with Sjögren's syndrome
lymphoid interstitial pneumonia
bronchiolitis obliterans with/without organising pneumonia
Although successful medical management of pulmonary gangrene has been described, the majority of cases have been treated surgically, either by drainage or resection. Our patient was treated with antibiotic therapy (penicillin G 4 million U six times daily for 4 weeks and tobramycin 80 mg intravenously bid during the first 2 weeks) and percutaneous drainage.
Pulmonary gangrene involves massive necrosis of lung parenchyma secondary to an overwhelming inflammatory pyogenic process that is mediated by thrombosis of small and large arteries. The presence of lung tissue within a cavity is the result of secondary pulmonary infarction. The most frequently involved microorganisms areKlebsiella pneumoniae andStreptococcus pneumoniae. Other pathogens may be involved, including other Gram-negative bacilli,Mycobacterium tuberculosis and anaerobes.1 2 S pneumoniae has been described as the responsible microorganism in 11 cases, including the present one.
The pathophysiology of pulmonary gangrene is not well defined. The mechanism is multifactorial, including both microorganism and host factors. Serotype 3 pneumococci are known to cause more severe necrosis than other types.3 In our patient, not only were serotype 35 pneumococci isolated, moreover, she suffers from a primary Sjögren's syndrome. Pulmonary abnormalities in patients with primary Sjögren's syndrome have been well documented.4Peripheral airways can be involved and the result is respiratory tract infection. Another factor associated with Sjögren's syndrome is the presence of pulmonary vasculitis . The vasculitis process, by means of local activation of the coagulation cascade, could explain the thrombosis and accompanying infarction. This is the first documented case of pulmonary gangrene associated with Sjögren's syndrome.
Although definitive diagnosis requires pathological confirmation, the typical roentgenographic picture is virtually diagnostic.2The most useful procedure is CT, which shows the presence of lung tissue within the cavity. This cavity occurs in the upper lobes in 80% of cases.
The optimal therapeutic approach to infectious pulmonary gangrene has not been delineated accurately because of the extreme rarity of the condition. Antibiotic therapy alone may be effective, but in many cases urgent surgical measures are required.5 In this case, percutaneous drainage was a useful therapeutic procedure and no surgical measures were necessary.