Fig. 6.34 A-F. Pulmonary aspergillosis is frequently seen as a "fungus ball" within a pulmonary cavity. A A thin-walled tuberculous cavity in the right upper lobe of a patient from Tunis: there is a large fungus ball within the cavity, confirmed by the CT scan (B). C, D Radiographs taken in different positions can be used to show the movement of the fungal ball within the cavity. C In the erect position the large fungus ball lies in the bottom of the left apical cavity. D When the patient is lying supine with the head downwards, the fungus ball moves to the upper part of the cavity. The apical pleural thickening and fluid, and the contracted left upper lobe are shown on both radiographs. E A large fungus ball in the cavity in the right apex of an African patient. There is chronic but active disease elsewhere in the right lung, with another cavity in the right middle lobe. F Fungus balls can be bilateral, as in this patient from South Africa. (A, B courtesy of Professor H. Gharbi, Tunis; E, F courtesy of the Radiology Library, University of Cape Town)

Clinical Characteristics

Aspergillosis presents clinically with a wide spectrum, from peaceful coexistence to severe illness. The clinical symptoms depend on the site, and more particularly on the status of the host's immune system and on whether the patient is granulocytopenic. It is in those who are already severely ill or immunocompromised that there will be dissemination and invasion. Chronic infection and the carrier state occur in atopic individuals, but colonies of the fungus may grow, as in aspergillomas, without any clinical reaction: in some patients, however, an apparently asymptomatic aspergilloma in a cavity provokes high antibody titers to the fungal antigens. In such patients it is probable that the cavity is the result of the fungus infection and did not preexist.
When the lungs are infected, the clinical presentation suggests bronchitis, with increased cough and sputum. The sputum is often tenacious, leading to .poor bronchial drainage and accumulation of pulmonary secretions. This results in secondary atelectasis and bacterial infection, which either causes or complicates bronchiectasis. Even when clinical symptoms are minimal, imaging may show recurrent pneumonia. In other pulmonary infections a predominant symptom is asthma, often associated with fever and cough, and with brown plugs of aspergilli in the sputum. In the early stages of this intrinsic asthma, the airway obstruction is reversible but later there are destructive changes, which may be recognized clinically by the development of the antibodies.

Another common clinical site of infection is a paranasal sinus, often due to A. flavus (which is endemic in the Sudan and Middle East). These patients may have no predisposing ill health, and the majority will have normal chest radiographs. The disease progresses slowly and without pain, and frequently presents as unilateral proptosis. Depending on the sinus infected, there may be frontal or facial swelling. The infection can be asymptomatic, but often extends into bone, sometimes into the cranium. The discrepancy between the gross imaging changes and the mild clinical symptoms is important because such spreading infections can be fatal.

Dissemination of the infection by hematogenous spread of the fungus can cause a fulminating disease. Infection may develop anywhere, most commonly in the central nervous system, the gastrointestinal tract, and the myocardium. Dissemination seldom occurs from an aspergilloma, which is usually noninvasive. Almost all disseminated infections originate in the lungs, sometimes following a concomitant infection, such as Pseudomonas aeruginosa, which commonly triggers invasive aspergillosis.

Apart from the brain, the urinary tract, particularly the kidneys, is commonly invaded. Bone infection is usually due to spread from a soft tissue focus: for example, when the sinuses are involved there may be periosteal thickening and as the disease progresses, lytic foci develop in the bones. Both clinically and on imaging, malignancy may be suspected because there is little bone sclerosis. The sinuses also have been the primary site of disseminated infections. Among the less common sites are the liver and the thyroid. The cause of death can be severe toxemia, hemorrhage from any site or massive septic pulmonary or other organ infarction.