Most mycetomas are due to
Aspergillus species. Some pulmonary findings of mycetomas due to
Candida have been reported. Necrotic lung balls are also usually detected in patients with pulmonary aspergillosis and they are distinct from aspergillomas with regard to their pathological features. An aspergilloma is a fungus ball component with only an aspergillus body. In contrast, a lung ball is composed of necrotic lung tissue. Almost all previous reports describing either lung balls or necrotic lung balls were seen in patients with pulmonary aspergillosis.
8,
9 One rare case of a lung ball caused by
Penicillium has also been reported.
10 However, to the best of the authors’ knowledge, there have been no previous reports of lung balls caused by candidiasis. Pulmonary candidiasis is difficult to diagnose, because
Candida species are so prevalent in the environment and within the human body. In fact, if
Candida species are detected from a respiratory sample, it may actually be contamination by
Candida from the oral cavity. Furthermore, there are no specific radiological features in pulmonary candidiasis. In the present case, bronchial brush cytology of a specimen obtained from the shadow area on CT scan by bronchofiberscopy revealed yeast, and bronchial wash cytology of the same region also revealed yeast. This means that
Candida definitely existed.
S. pneumoniae was also detected from the bronchial wash and sputum, in addition to the
Candida species, and it was of the mucoid type, which is known to generally cause pneumonia. In this case, the necrotic lung ball may have been caused by
S. pneumoniae. However, there was a high level of serum β-Dglucan, thus suggesting the existence of deep fungal infection. In addition, the patient’s blood was negative for
Aspergillus antibodies, and had a very low titer of
Aspergillus antigen, which indicated that the patient did not have aspergillosis. Therefore, it is suspected that this case of a necrotic lung ball was caused by a
Candida infection or co-infection with
Candida and
S. pneumoniae.
CT is able to accurately identify and depict the features of necrotic lung balls. In this case, the CT scan of the chest, at first, showed a lung ball shadow and the lesion disappeared after treatment with ITCZ. A cavitary lesion was then present instead of a round density (). The lung ball lesion was dissolved in a short period. As a result, this suggests that the ball shadow was necrosis of the lung, which is intriguing because the patient was young and not severely immunocompromised. The reason why a necrotic lung ball formed may be due to the fact that the patient had diabetes but not undiagnosed.
It was therefore concluded that
S. pneumoniae had a relatively large effect on the immune response. According to the authors’ review of the pertinent literature,
S. pneumoniae is seldom considered to be an etiologic pathogen of lung abscess, pulmonary gangrene, or necrotizing or cavitative pneumonia.
11 However, some reports indicate that these pulmonary diseases occur due to
S. pneumoniae.
12 Mucoid type
S. pneumoniae is considered especially virulent and to be one cause of lung abscess or purulent diseases. The authors could find no previous report describing a necrotic lung ball caused by
S. pneumoniae; the present case therefore provides new information regarding the etiology of lung ball formation. It is now evident that a necrotic lung ball may result from infection by
Candida and/or
S. pneumoniae, thus indicating that physicians should be aware that patients may still have a fungal infection of the lungs, even when they do not have either
Aspergillus antibodies or antigens, that may result in a lung ball.