Diagnosing Aspergillosis: The Role of Invasive Diagnostic Interventions

Abstract

The diagnosis of invasive aspergillosis remains challenging and current conventional methods are limited for the diagnosis of invasive fungal infections. The gold-standard for the definite diagnosis of proven invasive pulmonary aspergillosis remains either histopathologic, cytopathologic or direct tissue examination, based on the documentation of typical hyphae and a positive culture of Aspergillus spp. This chapter reviews the yield of invasive procedures in the diagnosis of aspergillosis. Biopsies may be taken percutaneously, bronchoscopically, via open surgery or video-assisted thorascopic surgery. Computed tomography-guided percutaneous, bronchoscopic and open lung biopsies have been performed with a diagnostic yield of 80–100, 51 and 70%, respectively. Bronchoscopy with bronchoalveolar lavage is generally helpful in diagnosing invasive pulmonary aspergillosis, especially in immunocompromised patients with diffuse lung involvement. The sensitivity and specificity of a positive result of bronchoalveolar lavage fluid are ~50 and 97%, respectively. All specimens obtained via invasive interventions including bronchoalveolar lavage should be processed for microscopy and cytology, fungal cultures and by means of any other available procedure (e.g., Aspergillus PCR and galactomannan). Combining microscopy and culture will increase the diagnostic yield by 15–20%. Combining culture, microscopy, serology, and Aspergillus PCR in lung tissues and/or bronchial samples will increase the diagnostic yield by 99%.