OVERVIEW

What is pulmonary cryptococcosis?

Pulmonary cryptococcosis is an acute, subacute, or chronic lung infection caused by Cryptococcus neoformans.

Cryptococcus neoformans primarily invades the lungs and brain but can also affect bones, skin, mucous membranes, and other organs.

Is pulmonary cryptococcosis common?

It is uncommon and considered an opportunistic infection, typically occurring in patients with long-term antibiotic use leading to dysbiosis or compromised immune function.

Immunocompromised conditions include cancer patients undergoing radiotherapy or chemotherapy, organ transplant recipients on long-term immunosuppressants, AIDS patients, and diabetics. Particularly in AIDS patients, cryptococcal infection has become a leading cause of death.

Is pulmonary cryptococcosis the same as typical pneumonia?

What the general public often refers to as pneumonia is bacterial pneumonia. However, many pathogens can infect the lungs, causing inflammation and nonspecific symptoms like cough, sputum, and fever.

Common pathogens include bacteria, viruses, fungi, Mycoplasma, and Chlamydia. Pulmonary cryptococcosis is a type of fungal lung infection.

Is pulmonary cryptococcosis contagious?

Pulmonary cryptococcosis is not a legally notifiable infectious disease but has a tendency to spread. Cryptococcus neoformans is widely distributed in soil, decaying fruit, dry bird droppings, and on the skin, oral cavity, or feces of healthy individuals.

Pigeon droppings are the primary source of human cryptococcal infections. However, it is essentially an opportunistic fungal pathogen, and individuals with normal immunity may experience mild or no symptoms after infection.

SYMPTOMS

What are the manifestations of pulmonary cryptococcosis?

• Most pulmonary cryptococcal infections have mild or even no noticeable symptoms. In severe cases, symptoms may include fever, cough, production of small amounts of white or gelatinous sputum, bloody sputum or hemoptysis, weight loss, and night sweats.

• Chest X-rays may show localized small patchy shadows, which can easily be misdiagnosed as tuberculosis or atypical pneumonia.

• Most patients can recover spontaneously, but some may develop chronic or disseminated infections. Chronic infections can form granulomas in the lungs, appearing as nodules or masses on chest X-rays, which are often misdiagnosed as lung cancer. Disseminated infections spread hematogenously, leading to extrapulmonary infections, with brain infections being the most severe.

• In immunocompromised patients, the infection can present as a fulminant form, causing acute respiratory distress syndrome (ARDS) with a high mortality rate. Chest X-rays may show multiple patchy consolidations or diffuse interstitial infiltrates in both lungs, possibly involving the pleura and leading to pleural effusion or pneumothorax.

Can pulmonary cryptococcosis cause other diseases?

Generally, no other complications occur. However, in patients with severely compromised immunity, hematogenous dissemination may occur, where the pathogen spreads through the bloodstream to other sites, causing infections. Severe cases may involve the brain, leading to meningitis or encephalitis.

CAUSES

What causes pulmonary cryptococcosis?

The pathogen of pulmonary cryptococcosis is Cryptococcus neoformans, a round yeast-like cell that reproduces by budding, lacks pseudohyphae, and forms yeast-type colonies in culture. It has a thick gelatinous capsule surrounding it, visible under India ink staining microscopy as a transparent capsule enveloping the fungal cells.

The main pathogenic factor is the capsule. Based on capsular polysaccharides, it is classified into four serotypes: A, B, C, and D. Clinical isolates are predominantly serotypes A and D, with serotype A being more common in China.

DIAGNOSIS

How is pulmonary cryptococcosis diagnosed?

Doctors generally diagnose it based on the patient's underlying conditions, predisposing factors, typical clinical manifestations, and pathogen testing, while excluding other diseases.

What tests are needed for patients with pulmonary cryptococcosis? Why are these tests performed?

• Sputum smear microscopy and culture: A positive sputum culture for Cryptococcus can aid diagnosis but is insufficient for confirmation, as healthy individuals may harbor Cryptococcus in their oral cavity. Therefore, direct sampling of lower respiratory secretions or lung tissue is required. To avoid contamination from oral or upper respiratory Cryptococcus, fiberoptic bronchoscopy or tracheal catheterization may be used to collect lower respiratory secretions or lung tissue for direct smear staining, microscopy, or culture. However, these invasive procedures carry risks and may require local or general anesthesia depending on patient tolerance.

• Blood tests: Elevated white blood cell count, mild to moderate increase in neutrophil percentage, possible anemia in later stages, and increased erythrocyte sedimentation rate.

• Imaging tests: Chest X-rays or CT scans can assist in diagnosis but cannot confirm the disease alone, as similar findings may occur with other lung infections or tumors.

• Immunological tests: The polysaccharide antigen in the capsule can be detected via latex agglutination or ELISA, providing high diagnostic value for Cryptococcus infection.

• Cerebrospinal fluid examination: For patients suspected of concurrent brain infection, cerebrospinal fluid biochemical and smear tests can confirm the diagnosis if Cryptococcus is identified.

What conditions should pulmonary cryptococcosis be differentiated from?

Pulmonary cryptococcosis should be distinguished from lung tumors, bacterial pneumonia, tuberculosis, viral pneumonia, parasitic pneumonia, and other fungal pneumonias.

TREATMENT

Which department should I visit for pulmonary cryptococcosis?

Respiratory Medicine.

Does pulmonary cryptococcosis require hospitalization?

It depends on the severity of the condition. Mild cases do not require hospitalization, but patients with weakened immune systems often develop severe disease and need inpatient treatment.

How is pulmonary cryptococcosis treated?

The goal of treatment is to control the infection and prevent disseminated cryptococcosis, particularly cryptococcal meningitis. Treatment depends on the patient's immune status and disease severity:

• For immunocompetent asymptomatic or mild cases, clinical observation or oral fluconazole for 3–6 months may be sufficient. Patients with slightly more severe symptoms may require extended treatment for 6–12 months.

• Severe cases, especially those complicated by cryptococcal meningitis, require a three-phase approach: induction, consolidation, and maintenance therapy. The induction phase typically involves amphotericin B (0.5–1.0 mg/kg/day) combined with flucytosine (100 mg/kg/day) for at least 4 weeks. Consolidation therapy consists of fluconazole (400 mg/day) for 8 weeks, followed by maintenance therapy with fluconazole (200 mg/day) for 6–12 months.

• Antifungal drugs may cause gastrointestinal side effects (e.g., nausea, vomiting, diarrhea), liver/kidney damage, bone marrow suppression, or electrolyte imbalances. Close monitoring of liver/kidney function, blood counts, and electrolytes is essential during treatment.

• Surgical resection may be necessary for patients with granulomas or localized infections unresponsive to medical therapy. Video-assisted thoracoscopic surgery (VATS) is preferred for localized pulmonary cryptococcosis, with care taken to avoid intraoperative compression. Postoperative antifungal therapy should continue for at least 2 months to prevent dissemination. Patients misdiagnosed with tumors or other conditions and surgically resected—later confirmed to have isolated pulmonary cryptococcosis—may be closely monitored if asymptomatic and serum cryptococcal antigen-negative.

• For recurrent cases, induction therapy should be prolonged (4–10 weeks). If fluconazole sensitivity declines, itraconazole or voriconazole may be considered as alternatives.

DIET & LIFESTYLE

Can pulmonary cryptococcosis be cured?

Early detection and treatment of pulmonary cryptococcal infection can help prevent meningitis. Primary pulmonary cryptococcosis can be completely cured with timely treatment, while cryptococcal meningitis is more severe, and early diagnosis improves the cure rate.

What dietary precautions should patients with pulmonary cryptococcosis take?

Consume more fresh vegetables and fruits to supplement vitamins, and eat high-quality proteins such as egg whites, milk, and fish.

What lifestyle precautions should patients with pulmonary cryptococcosis take?

Maintain a regular routine, avoid excessive fatigue and insufficient sleep, quit smoking and alcohol, manage emotions, avoid anger and agitation, stay in a positive mood, reduce stress, engage in appropriate physical exercise, and strengthen immunity.

Is follow-up necessary for pulmonary cryptococcosis?

Yes, follow-up is required. Patients undergoing long-term antifungal treatment need regular medical visits to monitor symptoms and signs. Chest X-rays should be repeated to assess lesion absorption, and liver/kidney function, blood tests, and electrolytes should be monitored. It is recommended to do so at least once a week.

PREVENTION

How to Prevent Pulmonary Cryptococcosis?

• Reduce pigeon populations and use alkaline treatment for pigeon droppings to control infection sources;

• Enhance immunity through balanced nutrition and moderate exercise;

• Avoid or minimize risk factors, such as strictly controlling the dosage and duration of antibiotic use, avoiding misuse of immunosuppressants like glucocorticoids, and maintaining proper blood sugar levels for diabetic patients;

• Strengthen HIV/AIDS awareness and improve management of HIV patients to reduce the incidence and severity of the disease.