B40: ICD10 Code for Blastomycosis
B40 is the ICD10 code used for documenting Blastomycosis in clinical and billing records.

B40 refers to Blastomycosis, a fungal infection that can affect the skin, lungs, brain, or other tissues. Mycoses vary in severity from superficial to systemic and may be life-threatening in immunocompromised individuals. Proper ICD10 coding ensures appropriate documentation, treatment, and tracking of fungal infections.
Symptoms
- Skin lesions – Scaling, redness, or itching in superficial infections
- Respiratory issues – Cough, chest pain, and shortness of breath in systemic mycoses
- Fever – Common in invasive fungal infections
- Fatigue – Especially in chronic or disseminated infections
- Swelling or abscesses – Seen in subcutaneous or deep mycoses
- Neurological signs – In infections like cryptococcosis affecting the CNS
- Weight loss – Often present in chronic systemic infections
Diagnosis
Diagnosis of Blastomycosis typically involves physical examination, microscopy, fungal cultures, histopathology, and molecular testing such as PCR. Imaging studies like X-rays or CT scans may be used to identify lung or brain involvement. Serologic tests may also aid in identifying systemic fungal pathogens.
ICD10 Code Usage
ICD10 code B40 is used to classify and report fungal infections across healthcare systems. It enables standardized documentation in EHRs, supports insurance claims, and contributes to epidemiological data. Accurate coding guides treatment protocols, especially for high-risk patients in hospitals or immunosuppressed populations.
Related Codes
- B35 – Dermatophytosis
- B36 – Other superficial mycoses
- B37 – Candidiasis
- B38 – Coccidioidomycosis
- B39 – Histoplasmosis
- B41 – Paracoccidioidomycosis
- B42 – Sporotrichosis
- B43 – Chromomycosis and pheomycotic abscess
- B44 – Aspergillosis
- B45 – Cryptococcosis
- B46 – Zygomycosis
- B47 – Mycetoma
- B48 – Other mycoses, not elsewhere classified
- B49 – Unspecified mycosis
FAQs
Q1: What is ICD10 code B40?
A: This code classifies Blastomycosis, a fungal infection, for clinical documentation and billing purposes.
Q2: Are fungal infections contagious?
A: Most are not contagious between humans, but can be acquired from the environment.
Q3: Are these infections dangerous?
A: Some superficial mycoses are mild, but systemic infections like aspergillosis or cryptococcosis can be life-threatening.
Q4: Who is at risk?
A: Immunocompromised individuals, transplant recipients, and those with chronic lung disease are at higher risk.
Q5: How are these treated?
A: Treatment involves antifungal medications such as fluconazole, amphotericin B, or topical agents for skin infections.
Conclusion
ICD10 code B40 is essential for identifying and managing Blastomycosis. It facilitates accurate diagnosis, guides clinical care, and helps public health authorities monitor the prevalence and impact of fungal infections. Proper coding improves patient outcomes and ensures effective medical and administrative handling.

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