The purpose of this study is to establish the accuracy with which the eNose can discriminate patients with invasive pulmonary aspergillosis from controls.

Inclusion Criteria:

Patients that

1. are 18 years of age or older
2. will undergo treatment for a hematological malignancy expected to result in grade 4 neutropenia (according to CTCAE 3.0, i.e. <0.5 x 109 neutrophils/L) of prolonged duration (i.e., more than 7 days), e.g. hematopoietic stem cell transplantation or induction/consolidation treatment for acute myeloid leukaemia
3. have given written informed consent

Exclusion Criteria:

1. a previously diagnosed invasive mycosis
2. the inability to perform the breathing manoeuvre needed for eNose-analysis of exhaled air

patients that will undergo treatment for a hematological malignancy expected to result in grade 4 neutropenia of prolonged duration