On this Mnemonic Monday, we challenge you to remember dermatophytosis of the hair (Ectothrix) where spores are found on the outside of the hair shaft, and fluoresce with Wood’s light with the following mnemonic:
Ectothrix: “Cats And Dogs Fight and Growl Sometimes”
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Need a refresher on Dermatophytes? Check out the following pages of your 2019 Derm In-Review Study Guide:
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Check out the following article published in the Journal of Drugs in Dermatology (JDD):
Background: Tinea capitis periodically undergoes demographic shifts in causative dermatophyte and therapeutic response to oral anti-fungal therapy.
Objective: To determine prevalent fungal species and response to standard antifungal therapy in inner-city children of color.
Methods: An IRB-approved chart review of demographic, clinical, diagnostic, and therapeutic data was conducted for children and young adults (0 to 18 years of age) who had scalp fungal culture performed for scalp hyperkeratosis and/or alopecia over a 2.5 year time-period. Supplemental parental phone interview was performed for missing data points.
Results: A total of 84 patients with final diagnosis of tinea capitis were identified—52% male, 60.6% African-American, 28.2% Hispanic, and 9.9% Caucasian. Complete resolution at 4 weeks was uncommon in all demographic groups (Hispanic: 11.7%, African-American: 41.3%). The Hispanic group and the youngest patients (aged less than 4 years) were less likely to respond to initial therapy, but the results were not significant. Of the 80 tinea capitis patients initially treated with griseofulvin, 41 out of 54 children (76%) had complete response to micronized suspension +/- crushed tablet (33% required shift to tablets from suspension) and 20 out of 26 (76.9%) cleared on crushed tablets alone. Of the 19 griseofulvin failures, 5 cleared on fluconazole suspension, 7 on terbinafine sprinkles, 3 on itraconazole therapy, and 4 were lost to follow-up. Of the 47 patients who could be evaluated long-term after a single course of oral griseofulvin at 6 weeks or greater, 38 had documented long-term mycological cure (80.8%) and 42 had long-term clinical cure (89%). Trichophyton tonsurans (n=40) was the most prevalent causative species identified on culture, followed by Alternaria species (n=10) and Microsporum canis (n=1).
Limitations: Retrospective chart review: patient population has a high rate of usage of over-the-counter antifungal creams and shampoos, affecting culture results.
Conclusions: Tinea capitis is still the most common cause of Trichophyton tonsurans in New York City. Response rates to griseofulvin are similar to rates seen in the 1970s but require higher dosing and conversion to crushed tablets in partial responders. Usage of crushed ultramicronized griseofulvin, terbinafine sprinkles, itraconazole, and fluconazole are alternative regimens for those children whose tinea capitis does not clear on griseofulvin suspension.
J Drugs Dermatol. 2012;11(7):852-856. Read the full article here.
Test your knowledge!
A 3-year-old girl is brought into clinic by her father, who reports that she has an itchy rash on the scalp. On exam, you notice a large oval erythematous scaly thin plaque. Wood’s light examination of the lesion demonstrates fluorescence. What is the most likely causative organism?
A: Trichophyton tonsurans
B: Microsporum nanum
C: Trichophyton rubrum
D: Candida albicans
E: Microsporum canis
To find out the correct answer and read the explanation, click here.
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