We illustrate a patient who developed IPA, superior vena cava (SVC) thrombosis and haemorrhagic mediastinitis due to Aspergillus. To our knowledge, this is the first case reported of the coexistence of SVC thrombosis and haemorrhagic mediastinitis complicating invasive aspergillosis, and the third reported case of SVC thrombosis caused by Aspergillus (1,2).
Aspergillus fumigatus is the most common cause of infection by Aspergillus in humans. This is a ubiquitous dimorphic fungus that primarily affects the lungs, causing a variety of pulmonary diseases. These can be divided into three groups: aspergilloma, invasive and semi-invasive aspergillosis, and allergic forms of aspergillosis (3). Invasive pulmonary aspergillosis (IPA) is a serious infection that requires severe impairment of host defense mechanisms, usually due to acute leukaemia and granulocytopenia from chemotherapy. Other risk conditions include corticosteroid use, allogeneic bone marrow transplant, solid organ transplantations (kidney, liver, heart), increased use of immunosuppressive regimens for autoimmune diseases, late-stage HIV infection, thoracic surgery and chronic obstructive pulmonary disease(9%).
Pathologically IPA is characterised by the invasion and thrombosis of small to medium-sized pulmonary arteries by fungal hyphae, which leads to haemorrhagic infarction with necrosis and cavitation. In tissue, Aspergillus forms septated hyphae that branch at 45° angles. IPA typically manifests with fever, cough, pleuritic chest pain, dyspnoea and haemoptysis. The diagnosis is difficult and should be suspected when airspace consolidation does not improve with broad spectrum antibacterial therapy.
Computed tomography (CT) may be useful in certain circumstances, particularly in cases of fever despite intensive therapy with antibiotics, and it plays an important role in early diagnosis. Characteristic findings correspond to haemorrhagic infarcts and consist of nodules or pleura-based, wedge-shaped areas of consolidation, surrounded by a halo of ground-glass attenuation.
Histologically the "halo sign" represents haemorrhage around a focal area of lung infarction and it is best seen with high-resolution CT (3,4). This early sign is nonspecific and a similar appearance has been described in tuberculosis, mucormycosis, candidiasis, herpes simplex and cytomegalovirus pneumonias, Wegener granulomatosis, Kaposi sarcoma and haemorrhagic metastases. However, in the appropriate clinical setting, the CT halo sign is highly suggestive of IPA.
Cavitation in the nodules or masses is a late finding that occurs with recovery from neutropenia, and it is associated with a better prognosis. It typically results in a distinctive radiographic appearance, the "air crescent" or "meniscus" sign. This finding is an air crescent near the periphery of a lung nodule formed by contraction of infarcted tissue, trapping air between the necrotic lung and the healthy surrounding parenchyma. Aspergillus may disseminate beyond the lung by haematogenous spread to the central nervous system, kidney and gastrointestinal tract (25-50%). Chest wall or mediastinal invasion can occur, but pleural and pericardial involvement and the presence of adenopathy are rare. Mortality may exceed 90%, and has not changed significantly over the past decades, despite the introduction of itraconazole and lipid formulations of amphotericin B. At present, invasive aspergillosis is the leading cause of infection-related mortality in many immunocompromised hosts.
