Aspergilloma

Seedling
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Diagnosis and reasoning

This middle aged gentleman has presented with prolonged hemoptysis and symptomatic anemia. Given his history of pulmonary tuberculosis (PTB), reactivation is an important possibility, although the absence of weight loss and constitutional symptoms argue against this. Bronchiectasis (which is an important complication of PTB) is another possibility, although such patients are usually symptomatic for a longer period (i.e. months to years, rather than weeks). Chronic obstructive pulmonary disease (COPD) should also be considered, as this is a leading cause of hemoptysis. However, the absence of a history of smoking is a strong argument against this diagnosis. Last, but not least, in patients of this age, the possibility of a bronchogenic carcinoma should always be kept in mind (even in the absence of identifiable risk factors) Note that hemoptysis may be caused by granulomatous diseases (i.e. Wegener’s granulomatosis), autoimmune diseases (i.e. Goodpasture syndrome), and even pulmonary vascular conditions (i.e. arteriovenous malformations and pulmonary venous hypertension). However, these are relatively uncommon, and should only be considered once the above differentials have been satisfactorily excluded. His unremarkable examination makes bronchiectasis and COPD less likely. The other diagnoses cannot be excluded via clinical features alone. A chest x-ray is a good first line investigation, and in this patient shows a heterogeneous opacity in the left upper lobe. Is this a tuberculous cavitation ? A lung abscess ? Or is it a fungating tumor ? A CT scan is essential for further discrimination. The CT scan sheds light by showing the lesion to be cavitary, with a mass lesion inside. This is suggestive of an aspergilloma - a rare complication of cavitary tuberculosis. The positive precipitin test subsequently clinches the diagnosis by providing serological evidence of aspergillosis. Surgical resection is the treatment of choice in this patient. This should be preceded by pulmonary function testing. While studies have shown endobronchial miconazole to be of some benefit in treatment of aspergilloma, there is no good evidence supporting IV miconazole therapy. Antituberculous therapy is not indicated in absence of evidence of reactivation; radiotherapy is of no use in his management.


Discussion

Aspergillus spp are ubiquitous fungi which may be acquired via inhalation of airborne spores. They are capable of causing a wide range of pulmonary diseases, depending on the immune status and presence of pre-existing pulmonary pathology in the host. The commonest subspecies encountered is A. fumigatus, followed by A. flavus and A. niger. Aspergilloma is the most common and best recognized form of pulmonary involvement, developing in a pre-existing cavity in the lung. Other recognized manifestations include allergic bronchopulmonary aspergillosis (ABPA), which results from hypersensitivity to Aspergillus antigens and is seen in patients with asthma and cystic fibrosis; invasive pulmonary aspergillosis, which is encountered in immunocompromised individuals; and chronic necrotizing aspergillosis, which occurs in patients with chronic lung disease or mild immune deficiency. An aspergilloma is a fungal ball consisting of fungal hyphae intertwined with mucus, fibrin, inflammatory cells and tissue debris. This may occur inside any cavitary lesion - especially those secondary to diseases such as tuberculosis, sarcoidosis or neoplasms, bronchial cysts or bullae. Note that the fungus usually does not invade the adjacent lung parenchyma or blood vessels - thus, it is considered a benign saprophytic colonization of the lung. These patients may remain asymptomatic for years. The most common presentation is mild hemoptysis; however, severe and life threatening hemoptysis may occur - particularly in patients with tuberculosis. Other symptoms such as cough and dyspnea may occur, although these are usually more related to the underlying lung disease. The diagnosis is usually made based on clinical and radiographic features combined with serological evidence of Aspergillus. Aspergilloma appears in the chest radiograph as an upper lobe intracavitary mass with an air crescent in the periphery. A change in the position of the mass may be noted after moving the patient. In addition, thickening of the cavity wall and adjacent pleura may also be seen. In many patients, a CT of the thorax may be necessary for better visualization. Serum IgG antibodies to Aspergillus are positive in almost every patient. Sputum examination demonstrates the fungus in only 50% of cases. The only definitive form of treatment is surgical resection, which is associated with a high morbidity and significant mortality, with important complications including hemorrhage, bronchoalveolar fistula formation, empyema and respiratory failure. Thus surgical resection is usually restricted to patients with severe hemoptysis and adequate pulmonary function. Asymptomatic and mildly symptomatic patients are best managed conservatively. While several studies have shown promising results with endobronchial antifungal therapy, this is yet to become established as a mainstream form of therapy. It is important to note that aspergilloma remains stable in the majority of patients; in 10% of the cases it may reduce in size or undergo spontaneous resolution without therapy.


Take home messages

  1. Aspergillomas develop in a pre-existing cavity in the lung.
  2. The fungus usually does not invade the adjacent lung parenchyma or blood vessels.
  3. The diagnosis is made via clinical and radiographic features combined with serological evidence.
  4. Resection is the only definitive form of treatment so far.

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  1. CHEST Journal: The Clinical Spectrum of Pulmonary Aspergillosis (June 2002)
  2. Clinical Infectious Diseases: Practice Guidelines for Diseases Caused by Aspergillus (2000)
  3. QIM: Pulmonary Aspergillosis: A Clinical Update (2007)
  4. RadioGraphics: Spectrum of Pulmonary Aspergillosis: Histologic, Clinical and Radiologic Findings (July 2001)