B40 Blastomycosis

Name of the Condition

• Blastomycosis

Summary

Blastomycosis is a fungal infection caused by Blastomyces dermatitidis (and related species) that primarily affects the lungs but can disseminate to other body sites. The condition may present as an acute or chronic pulmonary infection, with potential for systemic involvement in severe cases. Clinical manifestations range from asymptomatic infection to severe, life-threatening disease, particularly in immunocompromised individuals.

Causes

The infection is caused by inhaling airborne spores of Blastomyces fungi, which are found in soil and decaying organic matter (e.g., wood, leaves) in endemic regions. The spores convert to yeast in the lungs, where they multiply and may spread hematogenously to other organs, including the skin, bones, and central nervous system. Direct inoculation (e.g., 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.
• Disseminated: Skin lesions (nodules, ulcers, or verrucous plaques, often on the face/ extremities), bone pain, genitourinary symptoms, or central nervous system involvement (headache, confusion).

Diagnosis

Diagnosis is confirmed by identifying Blastomyces organisms in clinical specimens (e.g., sputum, tissue biopsy, or cultures). Microscopic examination of specimens may show broad-based budding yeast. Serologic tests (antigen/antibody) and imaging (chest X-ray/CT) support diagnosis, especially when cultures are negative. Histopathology of tissue samples is definitive.

Treatment Options

• Mild-to-moderate pulmonary disease: Oral antifungals (e.g., itraconazole) for 6–12 months.
• Severe pulmonary or disseminated disease: Intravenous amphotericin B initially, followed by oral azole therapy.
• Monitoring for treatment response and potential toxicity is essential.

Prognosis and Follow-Up

Prognosis is generally good with early treatment, but severe or delayed treatment may lead to complications. Follow-up includes clinical assessment, imaging, and laboratory monitoring to ensure resolution. Immunocompromised patients require longer treatment and closer surveillance.

Complications

• Acute respiratory distress syndrome (ARDS).
• Disseminated infection (skin, bones, CNS).
• Chronic lung disease or fibrosis.
• Meningitis or brain abscesses (rare but severe).

Lifestyle & Prevention

• Avoid disturbing soil in endemic areas (e.g., wear masks during excavation).
• Promptly clean skin wounds exposed to soil.
• Immunocompromised individuals should minimize high-risk exposures.

When to Seek Professional Help

Seek care if respiratory symptoms (cough, fever, chest pain) or unexplained skin lesions develop after potential exposure. Urgent evaluation is needed for severe respiratory distress, confusion, or systemic symptoms.

Tips for Medical Coders

Code B40 is assigned for blastomycosis, regardless of site (e.g., pulmonary, cutaneous, disseminated). Documentation should specify the infection site and severity (e.g., acute vs. chronic, localized vs. disseminated) to support coding accuracy. Ensure no conflicting diagnoses (e.g., other fungal infections) are present.