Overview.
Pulmonary cryptococcosis is a subacute or chronic visceral fungal disease caused by infection with a novel cryptococcus (pod-coated yeast). It mainly affects the lungs and the central nervous system, but may also invade bones, skin, mucous membranes, and other organs. Infection with this fungus causes only a mild inflammatory response. There is limited or extensive granuloma formation in the lungs; necrosis and cavitation are rare, and calcification and hilar lymph node enlargement are extremely rare. Small nodules may also form in the subpleura. Cryptococcus may produce lesions in the gray matter portion of the coronal section of the brain, which can cause meningoencephalitis. In the early stages of cryptococcal infection of the lungs, most patients may be asymptomatic; a few present with low-grade fever, mild cough, coughing up mucus sputum, and occasional signs of pleurisy. Cryptococcal infection in AIDS patients is frequently widely disseminated. Acute respiratory distress syndrome (ARDS) can occur in patients with severely compromised immune function.
Etiology
Immunocompromise is an important trigger for cryptococcal pathogenesis. Cryptococcus is inhaled via the respiratory tract and, under the influence of carbon dioxide concentration, forms a protective layer of polysaccharide pods to antagonize host defense mechanisms. Initial foci of infection are formed in the lung tissue, causing enlargement of hilar lymph nodes, and small nodules may also form under the pleura, resembling Mycobacterium tuberculosis infection.
The novel cryptococcus has an affinity for the meninges and brain parenchyma, and the central nervous system is the most common site of involvement; other rare sites of invasion are the skin, bones, prostate, liver, heart, and eyes. A mild inflammatory response characterizes the reaction. Advanced lesions are granulomas with occasional caseous necrosis and cavity formation in the lungs. The organism usually enters the body via the respiratory tract. The first site of infection is the lungs.
Overworked or chronically ill patients with immunodeficiency (e.g., advanced malignancy, leukemia, long-term treatment with high doses of hormones, broad-spectrum antibiotics, and anticancer drugs), inhalation of the fungus creates foci in the lungs, which spread throughout the body via the bloodstream, and most often invade the central nervous system.
Symptoms
In the early stage of cryptococcal infection in the lungs, most patients are asymptomatic, while a few may present with low-grade fever, mild cough, coughing up mucus sputum, and occasional symptoms of pleurisy. Cryptococcal infection is frequently widely disseminated among AIDS patients. In patients with severely compromised immune function, acute respiratory distress syndrome (ARDS) can occur. In recent years in patients with coexisting HIV infection (HIV), a cool interstitial infiltrate resembling Pneumocystis carinii infection has become more common. Because cryptococcal infection of the lungs can recur with other disease processes in the lungs, x-rays are even less typical.
Examination
1. Laboratory tests
Blood leukocyte count and neutrophils are mildly and moderately elevated, and anemia may be present in the middle to late stages. Blood sedimentation is increased.
2. Other auxiliary examinations
X-ray manifestations are diverse, with mild cases showing only increased texture or isolated nodular shadows in the lower part of both lungs, and occasional cavity formation. Acute interstitial inflammation is characterized by diffuse infiltration or corn-like foci. In patients with concurrent HIV infection, the more common presentation resembles the interstitial infiltrates of Pneumocystis carinii infection. X-rays are not typically characterized because cryptococcal infection of the lungs can recur with other disease processes in the lungs.
Diagnosis
Cryptococcosis of the lungs may be present alone or in conjunction with cryptococcosis elsewhere. About 1/3 of patients are asymptomatic and are often detected on chest X-ray and sometimes misdiagnosed as lung cancer. Most patients may have mild cough, cough a small amount of mucus sputum or blood sputum, chest pain, low-grade fever, fatigue and weight loss. A few patients present with acute pneumonia, occasionally with chest pain or signs of solid lung lesions and pleural effusion. When complicated with cerebrospinal meningitis, the symptoms are obvious and severe. The symptoms and signs of meningoencephalitis can be seen in patients with moderate fever, occasionally up to 40 ℃, and the lesions can be seen in the middle and lower lungs bilaterally or unilaterally or confined to one lobe of the lungs on X-ray.
Differential diagnosis
1. Tuberculosis
Tuberculosis is caused by tuberculosis infection. Mostly seen in adults, the lesions are mostly in the upper and lower clavicle, flaky or flocculent, with blurred borders, the lesions can be caseous necrotic foci, which become caseous (tuberculous) pneumonia, and the necrotic foci are wrapped by fibers to form tuberculous balls.
2. Primary or metastatic lung cancer
Lung cancer is a common malignant tumor, and its incidence and mortality rate are increasing. Early diagnosis of lung cancer is an effective way to improve therapeutic efficacy. Imaging and sputum exfoliative cytology examination can help to differentiate the two.
Treatment
Patients with chronic obstructive pulmonary disease (COPD) who have cryptococcal parasitism alone should be followed up regularly in the absence of evidence of lung invasion. Patients with lung parenchymal invasion on chest radiograph and isolation of novel cryptococci on culture of respiratory secretions should be treated aggressively to prevent hematogenous dissemination. Systemic therapy should be initiated very early in immunocompromised patients, even if their cerebrospinal fluid examination is negative, because of the high risk of pulmonary dissemination to the central nervous system. The drug of choice is amphotericin B.
Infection with Cryptococcus neoformans occurs in 7% of AIDS patients and should be treated with antifungal therapy. Amphotericin B and flucytosine (5-fluorocytosine) should be used in combination.
Those with evidence of cryptococcal infection and mild clinical symptoms can be treated with oral fluconazole or itraconazole. Pharmacologic therapy is effective in the vast majority of patients. Complete resection of cryptococcal nodules or masses in the lungs to control the infection is not possible in most cases, except in the minority of those with a single nodule for whom surgical treatment is effective. In a small number of patients, drainage assistance is required for pleural leakage.
Prognosis
The pathogen can also invade the central nervous system and has an affinity for the meninges and brain tissue; therefore, 80% of cerebral cryptococcosis infections are fatal.
Questions you may be concerned about
Is there a cure for pulmonary cryptococcosis?
It is possible to cure pulmonary cryptococcosis, but the chances of cure are related to the severity of the disease and the response to treatment.
Pulmonary cryptococcosis is caused by a cryptococcal infection and is a relatively common infectious disease of the respiratory system. If the infection is mild, it is possible to cure the disease if it is treated promptly and the cryptococcus has not infected the central nervous system.
If the disease develops rapidly, is more serious, and is not treated in time, in addition to the invasion of the lungs, it may also invade other parts of the body, resulting in poor treatment and a significant decrease in the cure rate, which is then greatly reduced.
In addition to this, it is also related to the patient’s age, their own physical fitness, and whether they have underlying diseases. If pulmonary cryptococcosis is diagnosed, early and standardized treatment is recommended to minimize delays.