Sporotrichosis USMLE Notes & Mnemonics contains all the high-yield points you need to know.
- Sporotrichosis: A fungal infection caused by Sporothrix schenckii, typically affecting the skin, subcutaneous tissues, and sometimes lungs or other organs.
Epidemiology:
- Often seen in gardeners, farmers, and others who work with soil or plants.
- Common in tropical and subtropical regions.
Transmission:
- Inoculation through skin from contaminated plant material, soil, or wood.
- Not transmitted from person to person.
Pathophysiology:
- The fungus enters through a break in the skin and then causes a localized or lymphocutaneous infection.
Clinical Features:
- Cutaneous Sporotrichosis: Most common form.
- Small painless nodule at the site of inoculation.
- Nodules may ulcerate and spread along lymphatic channels.
- Lymphocutaneous Sporotrichosis:
- Ascending lymphangitis with nodules along the lymphatic vessels.
- Disseminated and Pulmonary Forms: Rare, may occur in immunocompromised individuals.
Diagnosis:
- Culture: Gold standard; samples from skin lesions or sputum.
- Biopsy: Reveals granulomas with asteroid bodies.
- Serologic Tests: Can support the diagnosis but are less commonly used.
Treatment:
- Itraconazole: First-line therapy for cutaneous and lymphocutaneous forms.
- Potassium Iodide: Oral solution can be effective, especially in resource-limited settings.
- Amphotericin B: For severe, disseminated, or pulmonary disease.
Prevention:
- Protective clothing and gloves for those handling soil, moss, or plants. (Ref)
Mnemonic: “SPORO”
- Soil and plants (source)
- Painless nodule (initial symptom)
- Oral Itraconazole (treatment)
- Rising lesions along lymphatics (lymphocutaneous form)
- Occupational risk (gardeners, farmers)
Chart: Forms of Sporotrichosis and Their Features
| Form | Features | Treatment |
|---|---|---|
| Cutaneous | Painless nodules, ulceration | Itraconazole |
| Lymphocutaneous | Nodules along lymphatic channels | Itraconazole or Potassium Iodide |
| Disseminated/Pulmonary | Systemic symptoms, lung involvement | Amphotericin B |
Note: In USMLE exams, sporotrichosis might be presented in a vignette describing a patient with a history of gardening or outdoor work who presents with nodular skin lesions following the lymphatic distribution. Knowing the first-line treatment and the disease’s association with certain occupational exposures is crucial.
Check other important USMLE Notes
A Visual Learning Platform
