Blastomycosis
Background
- Fungus: Blastomyces dermatitidis
- Lives in moist soil, wooded areas
- Spores are airborne
- North, Central and South America
- Southeast and Midwest US (Mississippi and Ohio River valleys)
- Causes a systemic pyogranulomatous infection
- Reportable disease
Clinical Features
- Up to 50% of cases will be asymptomatic
- Incubation period: 3-6 weeks
- Flu like symptoms: Fever, chills, cough, muscle aches, joint pain, chest pain
- Other systemic symptoms: Weight loss, night sweats, chills
- Pulmonary: most common
- Acute or chronic pneumonia
- Diffuse pneumonitis, ARDS
- Skin:
- Verrucous lesion with irregular borders
- Microabscess (cold), subcutaneous nodules like erythema nodosum
- Ulcers that bleed easily and well-demarcated
- Bone: Osteomyelitis, chronic draining sinus, paravertebral abscess
- Genitourinary: Prostatitis, Epididymorchitis
- CNS: Meningitis, epidural abscess Brain abscess in immunocompromised
- Can involve breast, adrenal, thyroid, eye, lymph node, liver, spleen
Differential Diagnosis
- Pneumonia
- Malignancy
- Tuberculosis
- Histoplasmosis
- Pyoderma gangrenosum
- Keratoacanthoma
Evaluation
Workup
- Fungal culture (Blood, sputum, bone marrow, liver or skin) : Broad based buds
- Antigen test (Serum or urine)
- Histopathology
- Serologic testing
- HIV testing
- CXR: Alveolar infiltrates +/- cavitation, mass lesions, miliary or reticulo- or fibronodular pattern, pleural effusions, upper lobe infiltrate, perihilar lymph nodes
- Chest CT: Nodules, consolidation +/- cavitation, tree-in-bud opacities, pleural effusion, lack hilar adenopathy
- Xray of bone: Well-circumscribed osteolytic lesion
- Xray vertebrae: Lytic lesion in anterior vertebral body and destruction of disc space
- Bronchoscopy
Management
- ID consult
- Mild or moderate infections: Itraconazole (200mg TID x 3 days then once or twice daily x 6-12 months)
- Alternative: Fluconazole or ketoconazole (400-800mg/day)
- Azoles embryotoxic and teratogenic, avoid in pregnancy
- Severe infection: Amphotericin B (Lipid 3-5mg/kg IV daily or deoxycholate 0.7-1mg/kg IV daily)
- All immunocompromised patient should receive amphotericin B
- Lipid for all patients, except children
- If CNS involvement, lipid for all patients
Disposition
- Subclinical disease: Observation and no treatment
- Patients with immunosuppression or progressive pulmonary or extrapulmonary symptoms need treatment and often admission
- Some may need ICU