Melioidosis of the mediastinum

Abstract

Introduction: Melioidosis—caused by the Gram-negative bacterium Burkholderia pseudomallei—is a serious infection which is endemic to Northern Australia. The disease can present with an acute life threatening bacteraemic illness or less commonly as an indolent chronic infection. Rarely, the disease may present as a chronic, cavitating lung lesion or as mediastinal lymphadenitis, which can mimic tuberculosis or a malignant process. Two patients at our institution were referred with mediastinal lymphadenopathy with the presumptive diagnosis malignancy. Case 1. A 66-year-old female, ex-smoker, presented with a 12-month history of weight loss, malaise and cough. Chest imaging revealed mediastinal lymphadenopathy with a fistula between her right main bronchus and subcarinal lymph node. Bronchoscopy demonstrated necrotic material in the anterior/medial wall of her right main bronchus. Washings cultured Burkholderia pseudomallei and she was commenced on intravenous meropenem. Case 2. A 65-year-old male, ex smoker, with chronic renal failure necessitating haemodialysis, multiple skin squamous cell carcinomas and a history of melanoma, presented with a 5-month history of weight loss and cough. Chest imaging demonstrated necrotic mediastinal lymphadenopathy. A presumptive diagnosis of metastatic melanoma or squamous cell carcinoma was made. Endobronchial ultrasound guided transbronchial needle aspirate cultured Burkholderia pseudomallei. Intravenous ceftazidime was commenced. Conclusion: Mediastinal lymphadenopathy is a common condition seen by thoracic physicians with malignancy or sarcoidosis the two most common disease processes. Melioidosis can mimic a malignant process and culture of bronchial and nodal specimens plays an important role in determining this rare but life-threatening condition.