Invasive Aspergillosis Mimicking Metastatic Lung Cancer

Abstract

In a patient with a medical history of cancer, the most probable diagnosis of an ¹⁸FDG-avid pulmonary mass combined with intracranial abnormalities on brain imaging is metastasized cancer. However, sometimes a differential diagnosis with an infectious cause such as aspergillosis can be very challenging as both cancer and infection are sometimes difficult to distinguish. Pulmonary aspergillosis can present as an infectious pseudotumour with clinical and imaging characteristics mimicking lung cancer. Even in the presence of cerebral lesions, radiological appearance of abscesses can look like brain metastasis. These similarities can cause significant diagnostic difficulties with a subsequent therapeutic delay and a potential adverse outcome. Awareness of this infectious disease that can mimic lung cancer, even in an immunocompetent patient, is important. We report a case of a 65-year-old woman with pulmonary aspergillosis disseminated to the brain mimicking metastatic lung cancer.

Keywords: aspergillosis; brain abscess; brain metastasis; brain neoplasms; differential diagnosis; lung cancer; lung neoplasms.

Figure 1

Timeline. Abbreviations: ¹⁸FDG, 18-fluordeoxyglucose; CT, computed tomography; VATS, video assisted thoracic surgery; ¹⁸FDG-PET-CT, 18-fluordeoxyglucose positron emission tomography-computed tomography; EBUS-TBNA, endobronchial ultrasound with transbronchial needle aspiration; MRI, magnetic resonance imaging.

Figure 2

Evolution of thoracic lesions. Top: Follow-up chest computed tomography (CT) in 2011 showing a right-sided lobulated pulmonary mass at the right lower lobe (3.0-cm diameter). Middle: CT (left) and fusion 18-fluordeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET-CT) (right) in August 2013 shows an increase at the medial side of the mass and right hilar lymphadenopathy, with intense 18-fluordeoxyglucose (¹⁸FDG) uptake. Bottom: CT (left) and fusion ¹⁸FDG-PET-CT (right) in January 2014 showing further growth of the ¹⁸FDG-avid mass in the right lower lobe with hilar invasion and a mild ¹⁸FDG-avid subcarinal lymph node.

Figure 3

Brain magnestic resonance imaging in March 2014. T1-weighted image after gadolinium of the brain shows a small right frontal enhancing cerebral lesion.

Figure 4

Brain magnetic resonance imaging in May 2014. There is an increase in size of the right frontal lesion with surrounding perilesional edema. T2-weighted image (left) demonstrates a hypo-intense rim with ring-enhancement after gadolinium (contrast-enhanced T1-weighted middle). At diffusion imaging (right panels) there is restricted diffusion in a part of the central area.

Figure 5

Skin biopsy with presence of fungal hyphae. Periodic Acid Schiff stain on skin biopsy with fungal hyphae stained purple. Two fungal hyphae with dichotomous branching (diagnostic of Aspergillus) are depicted (arrows).

Figure 6

Cerebral biopsy with presence of fungal hyphae. Hematoxylin and eosin stain on cerebral biopsy showing nectrotic tissue with moderate numbers of septate fungal hyphae with parallel walls. Two fungal hyphae with dichotomous branching (diagnostic of Aspergillus) are depicted (arrows).