The spectrum of human diseases caused by members of the Aspergillus genus is extensive. It ranges from allergic reactions to colonization of preexisting pulmonary cavities to invasion and destruction of lung parenchyma with pyemic spread to brain, skin, and other organs, causing rapid death. The immune status of the host is a crucial factor in determining the phenotype and severity of the disease. In this case report Chronic Necrotizing Pulmonary Aspergillosis (CNPA), a rare, locally- or semi-invasive variant of pulmonary Aspergillosis, mimicking lung metastasis is presented. The 60-year-old male patient had earlier received multiple cycles of systemic chemotherapy due to colorectal carcinoma. Our case report focuses on the benefits and the possible disadvantages of PET-CT imaging in CNPA.