Pulmonary Meliodosis with Air Crescent Sign
Published on: 2019-08-14
Melioidosis results from infection with the soil and water bacterium Burkholderia pseudomallei. Disease occurs due to percutaneous inoculation or inhalation of aerosolized bacteria. Pulmonary melioidosis can present as acute bacterial pneumonia or cavitary lung lesions. Culture remains the mainstay for melioidosis diagnosis. Air cresecent sign is a useful clinical sign to diagnose aspergilloma. Here, we reported a case of pulmonary meliodosis with air crescent sign.
KeywordsAir crescent sign; Pulmonary meliodosis
A 68-year-old gentleman, non-smoker with uncontrolled type 2 diabetes (latest HbA1c was 11%) presented with chronic productive cough, intermittent fever and weight lost for one month duration. His initial chest radiograph showed a right middle zone consolidation. He was treated as lung abscess and was started on intravenous co-amoxiclav. His smears for AFB and sputum gene Xpert were negative. His CECT Thorax showed a right middle lobe heterogenous mass with a cavity and air crescent within and mediastinal lymphadenopathy. Serum galactomannan and serial blood cultures were negative. His bronchioalveolar lavage (BAL) culture grew Burkholderia pseudomallei thus confirming the diagnosis of pulmonary meliodosis. His BAL for fungal, mycobacterial stains and cytology were negative. He was treated with intravenous ceftazidime 2g qid for 4 weeks (intensive phase) followed by oral trimethoprim-sulfamethoxazole 320+1600mg bd (eradication phase) for three months along with strict sugar control. His repeated CT thorax showed resolution of the mass and he remains asymptomatic during follow-up.
An air crescent sign is commonly seen in invasive aspergillosis but can also occur due to pulmonary necrosis. It usually heralds recovery and is the result of increased granulocyte activity. Air crescent sign is a radiological sign whereby there is crescent shape radiolucency surrounding a parenchymal consolidation or nodular opacity . Monod sign described the mass or consolidation move to the dependent area . Air crescent sign can be seen in radiograph or computed tomography (Figure 1). By far, the commonest cause of air crescent sign is aspergilloma (Figure 2). Other differential diagnosis to be considered include pulmonary tuberculosis, pulmonary hydatid cyst, and Rasmussen aneurysm and lung carcinoma .
Air crescent sign is an important clinical sign to be recognized, however, it’s not pathognomonic for aspergilloma. We must always interpret this radiological sign according to our patient clinical presentation.
Figure 1: Thoracic CT (axial plane) showing an air crescent sign.
Figure 2: Thoracic CT (coronal plane) showing an air crescent sign.