Pulmonary cryptococcosis is a severe respiratory mycosis that occurs mainly in patients with severe immune disorders infected with pathogenic yeast–like fungi of the genus Cryptococcus. The clinical course resembles pneumonia, manifested by cough, shortness of breath, fever, hemoptysis. In some cases, pulmonary cryptococcosis is asymptomatic. The disease is diagnosed with the help of radiography and CT of the chest organs, laboratory research methods. Conservative antifungal therapy is prescribed, surgical intervention is performed if necessary.
B45.0 Pulmonary cryptococcosis
Pulmonary cryptococcosis (pulmonary thorulosis, European blastomycosis, Busse-Busche disease) refers to opportunistic infections, occurs in acute, subacute or chronic form, develops in persons suffering from immunodeficiency. It is a marker of AIDS. It is widespread everywhere. Over the past 20 years, there has been a significant increase in morbidity. About 1 million cases of the disease are registered annually, 70-90% of them – in HIV-infected patients, 10-25% – in patients with Hodgkin’s lymphoma. Two thirds of the cases are men aged 30 to 60 years. Children rarely suffer.
Causes of pulmonary cryptococcosis
The causative agent of the disease are yeast-like fungi of the genus Cryptococcus, representatives of the species Cryptococcus neoformans. Birds (pigeons, sparrows, canaries, long-tailed parrots and some others) serve as a natural reservoir of infection. Pathogens are found in the litter. The birds themselves do not develop the disease. Cryptococci are resistant to high and low ambient temperatures, persist in the soil for a long time and enter the human body when inhaling dust particles.
Micromycetes often inhabit the mucous membranes of the respiratory tract as saprophytes. Cryptococcosis occurs against the background of severe immunosuppression (less than 200 CD4 lymphocytes in 1 µl). The pathological process develops in 5-20% of AIDS patients and is one of the criteria for this condition. Patients with hemoblastoses and recipients of organs and tissues are less likely to get sick. Among hematological patients, cryptococcal-induced infection is more common in patients with lymphogranulomatosis.
The mechanism of the disease development is not fully understood. The entrance gates of infection are the respiratory organs, the transmission pathway is air–dust. Specialists in the field of infectology suggest that small (2-3 microns in size) cryptococcal cells enter the respiratory tract with dust. They reach the lungs with a current of air and are transformed into tissue forms. In individuals with a normally functioning immune system, fungi latently persist in the lung tissue for several months or years or cause a low-symptomatic, self-relieving inflammatory process.
Cryptococcosis develops against the background of inhibition of the cellular link of immunity. Pathogens actively multiply, cause primary inflammation of the pulmonary parenchyma. Intra-thoracic lymph nodes are often involved in the inflammatory process. Infection spreads hematogenically through the body, severe lesions of the brain and internal organs occur. Pathomorphological examination reveals foci of infiltration of lung tissue, lymphocytes, histiocytes, macrophages, disintegrating granulomas, in the center of which there are clusters of yeast-like fungi.
Symptoms of pulmonary cryptococcosis
According to clinical manifestations, the disease resembles pneumonia. The severity of the pathology varies widely. Immunocompetent individuals tolerate respiratory cryptococcosis easily, the symptoms of pathology are poorly expressed or absent. An increase in temperature to subfebrile figures, a prolonged dry cough can be stopped independently, without medical treatment. Signs of intoxication are not detected. The consequences of an infection are usually detected by chance during a routine X-ray examination of the lungs.
The pathological process in immunocompromised patients develops rapidly. More often, there is a primary lesion of the central nervous system by the type of meningoencephalitis with subsequent dissemination. Pulmonary cryptococcosis with a clinical picture of severe pneumonia is less common. The patient is worried about febrile fever, accompanied by dull aching pains in the chest. The inflammatory reaction of the pleura is manifested by an increase in the intensity of the pain syndrome, increased pain with deep breathing, coughing, physical exertion.
Cough is productive, sputum is released in moderate amounts, hemoptysis is often present. It is characterized by a rapid increase in signs of respiratory failure up to the development of respiratory distress syndrome. The respiratory rate and heart rate increase. Shortness of breath occurs with the slightest physical exertion and at rest. Patients complain of pronounced general weakness, sweating. In the subacute course of pathology and chronization of the process, in addition to a constant cough with scanty sputum, a gradual significant decrease in body weight is observed.
With immunosuppression, primary pulmonary cryptococcosis often leads to the further spread of infection and the development of a disseminated process with damage to the brain, kidneys and other organs. Without specific treatment, mortality reaches 100%, about 40% of HIV-infected people die from this pathology. Pulmonary hemorrhage and acute respiratory failure can also become the immediate causes of death. Chronically, the current process provokes the formation of pneumosclerosis, the appearance of pleurodiaphragmatic adhesions. Lung excursion is disrupted, chronic pulmonary heart failure gradually develops.
Diagnostic search for suspected cryptococcosis is carried out by infectious diseases doctors. During the survey and examination of medical documentation, the immune status of the patient is clarified. When collecting anamnesis, the professional route and hobbies of the patient are taken into account. Cryptococcosis of the respiratory organs often develops in pigeon breeders, breeders of canaries or parrots. Examination and physical examination can reveal non-specific signs of mycotic pneumonia. Auscultatively, wet wheezes are detected on both sides. When the pleurisy is attached, there is a sharp weakening of breathing and a shortening of the percussion sound on the side of the lesion. The final diagnosis is made based on the data of the following diagnostic techniques:
- Radiation studies. Multiple areas of pulmonary infiltration are detected on radiographs and computed tomograms of the lungs. Infiltrates are more often located in the lower lobes of both lungs, the lingual segments on the left and the middle lobe on the right. In some of them, decay cavities are determined. Sometimes there are signs of effusion in the pleural cavities, bilateral miliary dissemination. Cryptococcosis with an asymptomatic course is radiologically detected in the form of a single volumetric tumor-like formation (cryptococcoma).
- Bacteriological analyses. Microscopy of sputum obtained during bronchoscopy of bacterial lavage and biopsy material, blood is performed. When coloring with ink, large (up to 20 microns) tissue forms of micromycetes are visualized, enclosed in a dense transparent capsule. Sowing the material on standard nutrient media gives the growth of cryptococcal colonies within 3-10 days.
- Serological diagnostics. Latex agglutination and ELISA methods are used to detect fungal antigen (glucuronoxylomannan) in the patient’s blood serum. With the help of PCR, specific fragments of the DNA of the cryptococcus are established. This method of serodiagnostics has high accuracy, can be used to monitor the treatment of the disease.
All HIV-infected patients with the number of CD4 cells below 200 per 1 µl are subject to examination for cryptococcosis. Pathology should be differentiated with lymphoma, disseminated tuberculosis, pneumocystis pneumonia. Patients are prescribed consultations of a phthisiologist, pulmonologist, oncologist, hematologist. Taking into account the frequency of CNS damage, the severity of the course of thoracic meningoencephalitis, patients need to be examined by a neurologist.
Pulmonary cryptococcosis treatment
Conservative therapy with antifungal drugs is usually carried out. Surgical intervention is considered inappropriate, it is rarely performed. As a rule, single large cryptococcomas are resected. The schemes and duration of treatment depend on the form and severity of the pathology, the immune status of the patient. Antimycotics are used to prevent the dissemination of the process and life-threatening damage to the central nervous system. The principles of antifungal therapy of cryptococcal mycosis of the respiratory organs are determined by the state of the patient’s immune system:
- Management of immunocompetent patients. A randomly detected asymptomatic or low-symptomatic pulmonary cryptococcosis is usually stopped on its own. Patients are monitored with monitoring of the titer of cryptococcal blood antigens. Sometimes treatment with fluconazole is prescribed for a period of 3 to 6 months.
- Treatment of immunocompromised patients. In the isolated pulmonary form of the disease, drugs of the azole class are used in long courses. The combination of cryptococcal pneumonia with meningoencephalitis or a disseminated process are indications for the appointment of combination therapy with azoles and flucytosine.
Prognosis and prevention
The prognosis largely depends on the presence or absence of immune disorders. Individuals with normally functioning immunity easily tolerate cryptococcosis, and complete recovery is observed in the outcome. Patients suffering from immune disorders often develop a disseminated process, which significantly reduces the chances of recovery and increases the risk of death. Cryptococcosis is especially dangerous for HIV-infected patients who are not receiving antiretroviral therapy. Primary prevention of mycosis has not been developed. Patients with cryptococcosis infected with HIV are shown regular monitoring of an infectious disease specialist and lifelong administration of fluconazole.
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