II. Pathophysiology
- See Blastomycosis
- Caused by Blastomyces dermatidis
- Direct contact of non-intact skin with contaminated soil or decomposing timber
III. Symptoms
- Painful facial lesions (Pustules, ulcers or wart-type lesions)
IV. Signs
- Distribution: Face (esp. eyebrows)
- Verrucous form
- Starts as Papule or Pustule with slow enlargement
- Later, the lesion forms crust with irregular borders
- Secondary Subcutaneous Nodules and micro-abscesses may drain pus
- Ulcerative form
- Ulcerated lesion with sharp border
- Friable red granulation tissue at ulcer base may bleed easily
V. Diagnosis
- Fungal Culture
- Skin biopsy
- Microscopy of purulent discharge (with Potassium Hydroxide or Calcofluor stain)
- Yeast with broad-based buds (8-15 mm diameter)
- Urine Blastomyces Antigen test
- False Positive Histoplasma (high cross reactivity between organisms)
VI. Differential Diagnosis
- Furuncle
- Contagious Ecthyma (Orf)
- Pyogenic Granuloma
- Squamous Cell Carcinoma
VII. Management
- See Blastomycosis