Invasive aspergillosis (IA) is the most common mould infection in immunocompromised patients with haematological disease. Voriconazole, a triazole, improves overall survival of patients with an IA and is the mainstay of therapy. Resistance of A. Fumigatus emerged as an important clinical problem and infections with azole resistant Aspergillus have a high mortality. Nowhere in the world, azole resistance is more prevalent than in the Netherlands. Rapid detection of resistance is key to improve the patient's outcome but fungal cultures take time and are often negative. The investigators aim to detect azole resistance associated mutations in fungal DNA extracted directly from serum or plasma to accelerate diagnosis and improve outcome of patients infected with azole resistant A. fumigatus.

Inclusion Criteria:

• 18 years or older.
• Lung CT shows lesions that fulfil the EORTC/MSG radiological criteria of possible invasive fungal infection.
• A bronchoalveolar lavage is planned or has been performed <48hrs earlier

Exclusion Criteria:

- Patients unable or unwilling to provide consent

100 haematology patients with a radiologically suspected invasive pulmonary aspergillosis and undergoing a bronchoalveolar lavage. After the BAL diagnostic tests have become available, confirmation of the suspected infection is expected in 25 patients and therefore 25 evaluable patients will remain. The investigators decided that another 50 patients should be included because only 25% had an invasive fungal infection after interim analysis of the first 50 patients included.