Clinical History
History of inoperable carcinoma of the cervix, on chemotherapy, became neutropenic. Admitted to ITU with respiratory distress secondary to invasive aspergillosis, developed cavitating lung lesion which eroded through the mediastinum into the pericardium causing cardiac arrest and death.
Imaging Findings
A 21 year old female presented to the Intensive Care Unit with severe breathlessness. She was found to be neutropenic as a result of the chemotherapy she had been receiving for a recent diagnosis of inoperable carcinoma of the cervix. She was not known to have any pre-existing lung condition. Initial chest radiograph showed bronchopneumonia. She was ventilated and treated empirically for bacterial and fungal chest infection. Her condition improved during the first week, and antifungal and antibacterial drugs were discontinued.
Over the next week her condition deteriorated with chest radiograph findings compatible with widespread bronchopneumonia. As sputum culture was repetitively normal a bronchoscopy was carried out. Bronchoscopic washings grew aspergillus fumigatus and she was recommenced on antifungal drugs. Her condition failed to improve and a CT scan was carried out which demonstrated a large cavitating lesion within the right lung in close proximity to the mediastinum. The following day she went into EMD cardiac arrest in which initial CPR was successful. A chest radiograph taken immediately afterwards revealed pneumopericardium and bilateral pneumothoracies. Intercostal drains were inserted as a last resort but she died shortly afterwards.
The clinical suspicion was that the cavitating lesion had eroded through the mediastinum into the pericardial space.
The clinical picture, imaging findings and post-mortem were in keeping with the initial diagnosis of invasive Aspergillosis causing an area of lung parenchymal infarction in which an Aspergilloma developed. This later eroded through the mediastinum into the pericardium.
Discussion
Aspergillosis is regarded as a spectrum of disease usually due to Aspergillus fumigatus in the lungs with three major components:
1) Mycetoma(Aspergilloma) – usually in a pre-existing cavity and commonest form of pulmonary involvement due to Aspergillus
2) Invasive Pulmonary Aspergillosis(IPA) – mainly in neutropenic patients
3) Allergic Bronchopulmonary Aspergillosis – due to hypersensitivity to the fungus.
IPA was first described in 1953. The vast majority of IPA occurs in immunocompromised hosts and neutropenia in particular is the most important predisposing factor. The fungus erodes the lung parenchyma and other associated structures.
The chest radiograph findings are often variable and show non-specific changes. Lesions that are suggestive of IPA include ill-defined rounded areas of consolidation, often with pronounced air-bronchograms. Wedge shaped consolidations have been described, due to infarction secondary to vascular invasion. Areas of cavitation (often with the Air – Crescent sign) and rarely a miliary pattern can also occur.
The use of HRCT in IPA patients has been shown to be associated with a more favourable outcome, probably due to earlier diagnosis. Chest CT is more sensitive than plain film and findings range from multiple nodules to the ‘Air- Crescent’ sign and the ‘Halo’ sign. These two important signs on CT are characteristic of IPA.
The Air-Crescent sign occurs when air fills the space between and area of necrotic tissue and the surrounding lung parenchyma. The crescent becomes apparent when there is an opaque layer of haemorrhagic tissue peripheral to the air. This sign relies on neutrophil function and only occurs during marrow recovery, so is a late sign. It is estimated to be evident in 50% of cases.
During the neutropenic period the Halo sign may be seen on CT as an area of ground glass around a pulmonary nodule, which is representative of pulmonary haemorrhage.
Aspergilloma is a fungal ball that has developed in an area of damaged lung, usually due to Tuberculosis or other chronic lung conditions. It has been described in cavities caused by other fungal infections. An Aspergilloma may be asymptomatic for years or it may cause haemoptysis due to invasion of local blood vessels, rarely it invades lung parenchyma.
Radiologically, Aspergilloma is a Mid – Upper lobe cavity sometimes seen with a crescent of air. An interesting sign that may occur is the variation in the position of the central mass with a change in position of the patient. Aspergilloma may be present but not evident on the plain radiograph. CT is more sensitive at picking up Aspergilloma. Surgical treatment of Aspergilloma carries a relatively high mortality.
Pneumopericardium can be differentiated from pneumomediastinum on the plain radiograph. In the latter, the air tracks around the aortic knuckle, this is not seen in pneumopericardium.
Differential Diagnosis List
Invasive Aspergillosis and Aspergilloma causing Pneumopericardium.
Final Diagnosis
Invasive Aspergillosis and Aspergilloma causing Pneumopericardium.
