II. Pathophysiology
- Caused by Saprophytic, Dimorphic Fungus (Sporothrix schenckii) that inhabits soil and plants
- Prototypal example of Nodular Lymphangitis
III. Risk Factors: Exposures
- Soil or plant debris
- Thorns (gardening, esp. rose bushes, is a classic exposure)
- Sphagnum moss
- Timber
- Animal Bites or scratches
IV. Signs
- Primary lesion after 1-12 week incubation
- Small, painless pink nodular lesions develop at site of inoculation
- Secondary lesions
- Erythematous Papules, Nodules develop up lymph chain (Nodular Lymphangitis)
- Lesions ulcerate and drain clear serous fluid
- Other findings
- Rarely fever or regional adenopathy occur
- Extensive disseminated skin involvement without treatment
V. Differential Diagnosis
VI. Labs
- Routine fluid culture negative
- Culture of biopsied tissue shows saprophytic fungi
- Dimorphic fungi
- Yeast cells that reproduce via budding when cultured at 37 C
- Branching hyphae when cultured at 25 C
- Dimorphic fungi
VII. Management
- Apply warm compresses for 40 to 60 minutes per day
-
Antifungal for 2 months after lesion resolution
- Itraconazole 200 mg orally daily (preferred)
- Terbinafine (Lamisil) 250 mg orally twice daily
- Saturated Solution Potassium iodide (SSKI)
- Used in under-resourced regions
- Start 5 drops orally three times daily
- Titrated to 40-50 drops three times daily