II. Pathophysiology
- Caused by Blastomyces dermatidis (dimorphic Fungus)
- Rarest, but most pathogenic of the Fungal Lung Infections (Coccidioidomycosis, Histoplasmosis)
- Transmitted by exposure to contaminated soil or decomposing timber
- Inhalation of spores
- Traumatized, non-intact skin exposure (see Cutaneous Blastomycosis)
- Endemic regions of United States (surrounding large water bodies)
- Ohio River Basin
- Mississippi River Basin
- Great Lakes
- St. Lawrence River
III. Symptoms
- Pulmonary involvement is initially asymptomatic in 50% of cases
- Symptomatic patients have similar presentations to viral and Bacterial Pneumonia (but more insidious)
- Fever
- Night Sweats
- Cough
- Dyspnea
- Chest Pain (may be Pleuritic Chest Pain)
- Weight loss
- Nocturnal Joint Pain
IV. Signs
- Acute disease
- Self-limited Pneumonia may clear spontaneously in most patients
- Skin involvement (most common extrapulmonary manifestation of Blastomycosis)
- See Cutaneous Blastomycosis
- Characterized by Skin Ulcers
- Disseminated blastomyces lesions from hematogenous spread (severe cases may be fatal)
V. Imaging
-
Chest XRay of Chronic Blastomycosis
- Test Sensitivity: 66%
- Osteolytic lesions
- Pleural Effusions
VI. Lab
- Microscopy
- Broad-based budding
- Skin lesion Evaluation
- Pustular discharge for Potassium Hydroxide
- Skin biopsy
- See Cutaneous Blastomycosis
- Systemic disease
VII. Management
- Progressive, refractory, or severe disease or Central Nervous System involvement
- Amphotericin B 0.5-0.6 mg/kg (max 2.0 - 2.5 g) daily until stable
- After Amphotericin B IV course, transition to oral Itraconazole for 12 months
- Indolent disease (mild to moderate cases)
- Adults: Itraconazole 200 mg orally daily for 6 months
- Children and Pregnant women: Amphotericin B at dosing above
VIII. Course
- Incubation: 30-45 days
- Untreated, develops into chronic disseminated disease with progressive wasting