II. Etiology
- Not a true dermatophyte (tinea) infections
- Caused by yeasts (genus Malassezia)
- Pityrosporum orbiculare
- Pityrosporum ovale
- Malassezia furfur (prior name for organisms above)
III. Signs
IV. Diagnosis
-
Potassium Hydroxide (KOH)
- Scrape fine powdery scale with #15 blade
- Spaghetti (hyphae) and meatball (yeast) appearance
- Wood's Lamp (variably present)
- Irregular pale yellow fluorescence
- Fluorescence disappears with resolution
V. Differential Diagnosis
VI. Management
- Hypopigmentation resolves slowly after treatment
- Recurrent infections (recurrence rate is high)
- Consider repeat treatment prior to summer
- Frequently worn clothing may harbor fungus
- Consider discarding suspected clothing
- Consider boiling suspected clothing
- First Line: Topical Antifungal
- OTC versus prescription agents
- Both Selenium sulfide 1% (Selsun Blue) and Ketoconazole 1% (Nizoral A-D) are available OTC
- Best studied efficacy is with the higher concentration prescription items
- Efficacy of lower concentrations is unknown
- Selenium sulfide (Selsun, Exsel) 2.5% lotion
- Apply lather neck to knees
- Course
- Apply once daily for 7 days
- Wash off after 5-10 minutes
- Alternative regimen 1
- Apply three to five times per week for 2-4 weeks
- Wash off after 5-10 minutes
- Alternative regimen 2
- Apply once weekly for 4 weeks
- Wash off after 24 hours
- Zinc pyrithione
- Ketoconazole 2% cream
- Apply once daily for 14 days
- Terbinafine (Lamasil) topically
- May result in longer, sustained resolution
- OTC versus prescription agents
- Second line: Systemic Antifungal
- General
- Exercise to sweating after each dose
- May help distribute more medication to skin
- Avoid bathing for 12 hours after application
- Avoid oral Terbinafine due to low efficacy (possibly due to low skin concentrations)
- Exercise to sweating after each dose
- Fluconazole (preferred)
- 400 mg orally for one single dose OR
- 300 mg orally now and again in 2 weeks
- Itraconazole
- 400 mg orally daily for 3-7 days OR
- 200 mg twice daily for one day per month (to prevent recurrence)
- Ketoconazole
- Avoid due to hepatotoxicity risk (requires baseline and weekly Liver Function Test monitoring)
- Preveiously used at 400 mg orally for one single dose or 200 mg PO qd for 7 days
- General
VII. References
- (2014) Presc Lett 21(7): 41
- Habif (1996) Clinical Dermatology, Mosby, p. 402-5
- Gilbert (2013) Sanford Antibiotic Guide
- Plensdorf (2017) Am Fam Physician 96(12): 797-804 [PubMed]
- Savin (1996) J Fam Pract 43(2):127-32 [PubMed]
- Zuber (2001) Postgrad Med 109(1):117-32 [PubMed]