B40.0 Acute pulmonary blastomycosis

Name of the Condition

• Acute pulmonary blastomycosis

Summary

Acute pulmonary blastomycosis is a fungal infection of the lungs caused by Blastomyces dermatitidis (and related species). It results from inhaling airborne spores of the fungus, which convert to yeast in the lungs and may cause localized or systemic disease. The condition typically presents with respiratory symptoms and can progress to severe illness, particularly in immunocompromised individuals.

Causes

The infection is caused by inhaling spores of Blastomyces fungi, which are found in soil and decaying organic matter in endemic regions. The spores germinate in the lungs, where they multiply and may spread to other organs via the bloodstream. Direct inoculation through skin wounds is rare.

Risk Factors

• Residence in or travel to endemic areas (e.g., parts of North America, particularly the Ohio and Mississippi River valleys).
• Occupational or recreational exposure to soil (e.g., construction, forestry, gardening).
• Immunocompromised states (e.g., HIV/AIDS, organ transplantation, chronic steroid use).
• Male gender (higher incidence reported).
• Advanced age.

Symptoms

• Pulmonary: Cough (productive or non-productive), chest pain, dyspnea, fever, night sweats, weight loss.
• Systemic: Fatigue, myalgia, arthralgia.
• Disseminated disease may involve skin, bones, or central nervous system (e.g., skin lesions, bone pain, meningitis).

Diagnosis

Diagnosis involves clinical evaluation, imaging (e.g., chest X-ray or CT), and laboratory testing. Sputum or tissue samples may be examined for fungal elements, cultured, or tested via PCR. Histopathology of biopsy specimens can confirm yeast forms. Serologic tests (e.g., antigen detection) may also be used.

Treatment Options

Treatment typically includes antifungal medications, such as itraconazole for mild-to-moderate cases or amphotericin B for severe or disseminated disease. Duration of therapy depends on disease severity and response. Adjunctive measures (e.g., oxygen, supportive care) may be needed for respiratory distress.

Prognosis and Follow-Up

Prognosis is generally good with timely treatment, though severe cases or immunocompromised patients may have higher morbidity. Follow-up includes monitoring for symptom resolution, repeat imaging if needed, and ensuring completion of antifungal therapy. Relapse is possible, especially in immunocompromised individuals.

Complications

• Acute respiratory failure.
• Disseminated infection (e.g., skin, bones, central nervous system).
• Chronic pulmonary sequelae (e.g., fibrosis).
• Death in untreated or severe cases.

Lifestyle & Prevention

• Avoid exposure to soil in endemic areas, especially during activities that disturb dust (e.g., gardening, construction).
• Wear protective gear (e.g., masks) in high-risk environments.
• Prompt treatment of immunocompromising conditions to reduce severity risk.

When to Seek Professional Help

Seek care if respiratory symptoms (e.g., persistent cough, chest pain, dyspnea) or systemic signs (e.g., fever, weight loss) develop, especially after potential exposure. Immunocompromised individuals should seek care promptly due to higher risk of severe disease.

Tips for Medical Coders

Code B40.0 is used for acute pulmonary blastomycosis. Documentation should specify the acute nature of the pulmonary infection and exclude chronic or disseminated forms. Ensure clinical notes support the diagnosis, including symptoms, diagnostic testing, and treatment. Avoid coding for asymptomatic or unspecified blastomycosis.