Aspergillus balls

　　How are aspergillus balls caused? Briefly described as follows:

　　1. Etiology

　　Aspergillus balls are a kind of aspergillus that parasitizes in lung cavities, where the hyphae and cellular debris form a spherical mass. In addition to aspergillus, Mucor, Pseudozyma-like fungi, and Candida and other fungi can also occasionally cause similar lesions, but aspergillus is the most common. Aspergillus only grows in the form of hyphae, and the colony color is diverse. It appears fluffy or flocculent and is relatively stable.

　　2. Pathogenesis

　　Aspergillus balls are most commonly found in pre-existing lung cavities, including cavities formed by diseases such as pulmonary tuberculosis, bronchiectasis, lung cysts, sarcoidosis, histoplasmosis, ankylosing spondylitis, and malignant tumors, and occasionally in pleural cavities, especially in cavities formed by surgical scars or pleural adhesions. The invasion and implantation of aspergillus into cavities belong to saprophytic parasitism and are only accompanied by slight tissue invasion. The aspergillus balls growing in the cavities have poor drainage and blood supply. The aspergillus balls themselves are formed by the wrapping of aspergillus hyphae. Aspergillus grows on the wall of the cavity, tends to invade local structures, especially blood vessels, but rarely invades the lung parenchyma or spreads through blood vessels. In a few cases, aspergillus balls can change from a benign chronic process to an invasive one, even being fatal. Regarding the life cycle of aspergillus balls, some studies have shown that they grow into the cavity early on, and eventually appear as spherical shadows on X-rays, among which aspergillus may be living bacteria, or may also be dead bacteria. The outcome depends on which is dominant, living bacteria or dead bacteria; if the local environment is unfavorable for the growth of aspergillus, the aspergillus will eventually liquefy and be coughed out. The residual spherical lesions of dead aspergillus may occasionally calcify.

　　There is also a type of patient with no cavity in the lung at first, just irregular infiltration of local lung tissue with indistinct edges. However, as the disease progresses, the irregular infiltration gradually becomes round, the edges become clear, and cavities are formed, producing aspergilloma. This type is very rare, and there is also little research on it at present.

　　Aspergilloma often complicates with bacterial infection and pleural lesions, which have a significant impact on people's daily lives and seriously harm patients' health. Therefore, it is necessary to treat the disease in a timely manner once symptoms are found.

　　The most common symptom of pulmonary aspergilloma is hemoptysis, with an incidence rate of 50% to 90%, and the amount of hemoptysis also varies greatly, from a small amount to massive fatal hemoptysis. There are several hypotheses about the causes of hemoptysis, such as the mechanical friction and injury to blood vessels by aspergilloma with respiratory movement, hemolytic and anticoagulant effects caused by endotoxins in aspergillus, and the localized erosion of blood vessels in the wall of the cavity may also be a participating factor. Other common symptoms include chronic cough, occasional weight loss, and patients generally do not have fever unless complicated with bacterial infection. Aspergilloma adjacent to the pleura can cause pleural cavity infection, and individual cases can lead to bronchopleural fistula. Some patients present with an insidious course, asymptomatic for many years, but the vast majority eventually develop symptoms. Aspergilloma itself rarely has signs, and according to the scope, nature, and location of the underlying disease, corresponding signs can be found.

　　This disease belongs to fungal infection. Patients with the disease should wear masks to reduce the release of pathogens. People living in endemic areas should also wear masks to avoid the inhalation of fungal spores and hyphae. At the same time, actively treat infected patients to cut off the source of transmission.

　　What examinations should be performed for aspergilloma? Briefly described as follows:

　　1. Sputum culture can confirm the presence of aspergillus, but the positivity rate is not high, and fiberoptic bronchoscopy includes collecting lower respiratory tract specimens with anti-contamination techniques.

　　2. Bronchoalveolar lavage and bronchoscopic lung biopsy (lesion) can improve the sensitivity and specificity of aspergilloma diagnosis, and help differentiate from other fungal balls or pulmonary spherical lesions. The biopsy should be performed under imaging guidance to aim at the aspergilloma, without damaging the wall to prevent bleeding. Thoracic biopsy can also be performed in patients with pleural lesions.

　　3. Serum immunological examination is helpful for diagnosis. The positivity rate of antibodies in serum precipitants is nearly 100%, and it has high sensitivity and specificity for differential diagnosis of suspected aspergilloma in X-ray. The positivity rate of skin test in aspergilloma is only 22%, significantly lower than ABPA (positivity rate 99%).

　　4. On X-ray, aspergilloma appears as lung cavity or a circular dense shadow in the pleural cavity, with a translucent halo at the edge. If the cavity is large, the shadow of the spherical shadow can be seen to have a pedicle connected to the wall of the cavity, resembling a pendulum, and the spherical shadow can change shape with the body position. If the cavity is small and the spherical lesion fills most of the cavity, the halo is very small, only showing a narrow crescent-shaped transparent strip. Some scholars have applied bronchial artery angiography for localization in two cases of cryptogenic massive hemoptysis with no positive findings on X-ray flat films, tomograms, and bronchograms, and performed surgical treatment. Pathological examination found a small bronchial cyst of about 1 cm secondary to aspergilloma. Chest CT examination, especially the application of high-resolution CT, provides useful technology for the detection of small aspergilloma and differential diagnosis.

　　The dietary principles of aspergilloma are briefly described as follows:

　　1. Prefer light and savory foods, eat more vegetables and fruits, and pay attention to adequate nutrition. Eat more low-fat, low-sugar, low-salt, and non-spicy foods, which are relatively light in taste. From a nutritional perspective, light diet can best reflect the true taste of food and preserve the nutritional components of food to the greatest extent. Pay attention to a reasonable diet composition.

　　2. Avoid smoking and drinking, avoid spicy and greasy foods, avoid cold and raw foods.

　　Due to the unpredictable natural course of aspergilloma, there are many controversies about the indications for different treatment measures (no medication, medical treatment, surgical resection). In addition to the disease itself, treatment measures should also be considered in combination with underlying diseases, so treatment should be individualized. Those with no symptoms or mild symptoms can undergo medical observation. Those with symptoms but not suitable or refusing surgery can try medication. It is believed that only amphotericin B and itraconazole among the existing antifungal drugs are effective. The former is also recommended by some to use the cavity injection therapy. Surgical resection is the only radical treatment, suitable for cases with recurrent hemoptysis or risk factors affecting prognosis. It is reported that the perioperative use of amphotericin B can reduce the occurrence of complications such as bronchopleural fistula. If the patient's lung function is impaired and cannot withstand surgery, bronchial artery embolism is a very effective treatment for controlling massive hemoptysis, but the long-term efficacy is still not ideal. Some believe that radiotherapy promotes the occlusion of blood vessels around the aspergilloma, which helps to stop bleeding, but it has not been universally recognized.