B40.8 Other forms of blastomycosis

Name of the Condition

• Other forms of blastomycosis

Summary

Other forms of blastomycosis are fungal infections caused by Blastomyces dermatitidis (and related species) that affect body sites beyond the lungs, skin, bones, or central nervous system. These infections result from hematogenous spread of the fungus from a primary pulmonary site or, rarely, direct inoculation. Clinical manifestations vary by affected organ but typically involve localized symptoms related to the involved tissue. The condition is part of the broader blastomycosis spectrum and requires targeted evaluation based on the specific site of infection.

Causes

The infection arises from the dissemination of Blastomyces yeast, which originates from a primary pulmonary infection. Inhalation of airborne spores from soil or decaying organic matter in endemic regions initiates the disease. Once in the lungs, spores convert to yeast, multiply, and may enter the bloodstream to spread to other organs. Direct inoculation through skin wounds is uncommon but possible in certain exposures.

Risk Factors

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

Symptoms

Symptoms depend on the affected organ system and may include localized pain, swelling, or dysfunction. For example, genitourinary involvement could cause dysuria or hematuria, while gastrointestinal involvement might lead to abdominal pain or diarrhea. Systemic symptoms like fever, fatigue, or weight loss may also occur.

Diagnosis

Diagnosis involves clinical evaluation, imaging (e.g., CT, MRI) of the affected site, and laboratory testing. Tissue or fluid samples from the involved area are examined for Blastomyces yeast via microscopy, culture, or antigen testing. Histopathology may show characteristic broad-based budding yeast. Serologic tests or PCR may support diagnosis but are less commonly used.

Treatment Options

Treatment typically includes antifungal therapy, such as itraconazole for mild to moderate cases or amphotericin B for severe or disseminated disease. Duration depends on the site and severity of infection, often ranging from 6 months to a year. Surgical intervention may be needed for abscesses or tissue damage.

Prognosis and Follow-Up

Prognosis is generally good with prompt treatment, though outcomes depend on the site of infection and patient’s immune status. Follow-up includes monitoring for treatment response, symptom resolution, and potential recurrence. Immunocompromised patients may require longer therapy and closer surveillance.

Complications

Complications can include chronic organ damage (e.g., renal scarring, bone destruction), dissemination to other sites, or treatment-related toxicity (e.g., nephrotoxicity from amphotericin B). Delayed diagnosis may worsen outcomes.

Lifestyle & Prevention

Avoiding exposure to endemic soil (e.g., during excavation or outdoor activities) reduces risk. Wearing protective gear in high-risk environments and prompt treatment of pulmonary blastomycosis may prevent dissemination. Immunocompromised individuals should take extra precautions.

When to Seek Professional Help

Seek care if symptoms of localized infection (e.g., pain, swelling, or organ-specific dysfunction) develop, especially after potential exposure. Immediate evaluation is needed for severe symptoms (e.g., high fever, confusion) or if immunocompromised.

Tips for Medical Coders

Code B40.8 is used for blastomycosis affecting sites other than the lungs, skin, bones, or central nervous system. Document the specific affected organ (e.g., genitourinary, gastrointestinal) to support coding. Ensure clinical correlation with lab or imaging results to confirm the diagnosis and site of infection.