Chest ImagingCryptococcosis
The fungus
Cryptococcus neoformans typically lives in soil but is also found in pigeon droppings. Generally the disease is acquired by inhaling contaminated dust although a large number of patients with immunosuppression develop disseminated cryptococcosis.
Clinically patients may be asymptomatic or exhibit symptoms such as cough, fever, weight loss, haemoptysis and dyspnoea.
Radiographically there are a variety of abnormalities identified. Perhaps the most common is the appearance of well-defined nodules in the lung. These may measure from 2 to 5 cm in diameter and may cavitate (Fig.1). In immunosuppressed patients disseminated disease may result in bilateral heterogeneous reticular and linear and nodular opacities. Hilar and/or mediastinal lymphadenopathy does occur and may be the only finding in patients with cryptococcosis and AIDS. Pleural effusions are uncommon.
Diagnosis is generally made by identifying the yeast form in sputum or biopsy specimens or by positive culture. Positive cryptoccocal antigens may be seen in serum. Typical antifungal agents such as amphotericin B are favoured in treatment. Without treatment patients with disseminated disease have a poor prognosis.
PGO
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A thin to mildly thick-walled cavitating nodule is seen in the right lower lobe. A variety of abnormalities including multiple nodules and homogeneous lobar opacification may also be seen with cryptococcosis.
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Cryptococcosis, Fig.1 | |