cutaneous fungal infections susan massick, md osu dermatology e-mail:...
TRANSCRIPT
Cutaneous Fungal Infections
Susan Massick, MD
OSU Dermatology
E-mail: [email protected]
Phone: (614) 293-1707
Learning Objectives
Identify and diagnose cutaneous fungal infections
Plan treatment approaches for dermatophyte skin infections
What are Dermatophytes?
Dermatophytes: fungi that digest keratin Geophilic: soil keratin Zoophilic: animal keratin Anthrophilic: human keratin
Infection limited to keratin structures Stratum corneum Hair Nails
Types of Dermatophyte Infections
Tinea Capitis Tinea Corporis Tinea Cruris Tinea pedis and Onychomycosis Tinea Versicolor
Common genera: Microsporum, Trichophyton, and Epidermophyton
Tinea Capitis: Scalp Ringworm
Common fungal infection in children, especially African American children
Trichophyton tonsurans is most common anthrophilic organism to cause tinea capitis in U.S.
Microsporum canis is most common zoophilic organism to cause tinea capitis in U.S.
Clinical Manifestations of Tinea Capitis
Patches of alopecia with erythema and scaling
Small black dots
Diffuse dandruff
Kerion formation due to severe inflammation
Diagnosis of Tinea Capitis
Diagnosis can be established by KOH and fungal culture
Wood’s lamp can identify certain dermatophytes via fluorescence M. canis + fluorescence T. tonsurans - fluorescence
Treatment of Tinea Capitis
Tinea capitis must be treated with oral therapy
First line treatment: griseofulvin, which disrupts fungal microtubule formation
Other alternative oral medications include terbinafine, fluconazole, and itraconazole
Add shampoos, such as selenium sulfide, cicloprox, or ketoconazole, to decrease transmissibility of infection
Tinea Corporis
Also called ringworm
Red scaly ring with central clearing
May involve trunk, arms, legs, neck
Tinea Corporis: Diagnosis and Treatment
Most common fungal etiologies:
Trichophyton rubrum, Microsporum canis, and Trichophyton mentagrophytes
Diagnosis can be made by KOH exam
Can treat with topical antifungals for local disease and systemic oral antifungals, such as terbinafine or griseofulvin, if widespread
Tinea Cruris
Also known as “jock itch”
Presents as chronic brown to red patches in groin folds and upper/inner thighs
Rare before puberty, more common in men
Often spares scrotum, penile shaft, glans penis
Tinea Cruris
Should be differentiated from candidiasis, which is typically bright red, often involves scrotum, glans penis, may manifest satellite pustules
Common fungal etiologies include Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum
Usually responds to topical antifungal therapy
Tinea Pedis
Extremely common fungal infection of skin of feet
Commonly called “athlete’s foot”
Similar fungal organisms that cause tinea cruris: Trichophyton rubrum and mentagrophytes
Tinea pedis: Presentation and Treatment
Moccasin type causes redness and scaling of soles and sides of feet
Interdigital type produces white macerated fissures between the toes, usually 4th-5th spaces
Bullous type produces small blisters on sole of foot
Often responds to topical antifungal agents, such as topical terbinafine
Onychomycosis
Fungal infection of nails, or tinea unguium
When toenails involved, often associated with tinea pedis
May produce yellow or white discoloration of toenails with dystrophy or separation of nail from nailbed
Nails may become thickened or develop white powder under the nail
Fungal etiology is similar to tinea corporis: T. tonsurans, T. rubrum
Treatment of Onychomycosis
Usually requires systemic antifungal agents with terbenafine being most effective. Itraconazole is less effective.
Topical antifungals are less effective
Tinea pedis cannot be effectively treated long term unless onychomycosis is also eliminated.
Tinea versicolor (TV)
Due to an overgrowth of a yeast (Pityrosporum ovale), which thrives on lipids, such as sebum
Tinea versicolor (TV) usually presents as hypo or hyperpigmented macules with very fine scale on upper chest, upper back, shoulders
Hypopigmentation is due to dicarboxylic acid produced by the yeast, which inhibits melanin formation
Tinea versicolor: Diagnosis and Treatment
Diagnosis made on physical exam and KOH scraping with characteristic “spaghetti and meatballs” appearance of hyphae and spores
Treat with antifungal shampoos, such as selenium sulfide or ketoconazole, and/or with single doses of oral ketoconazole
Summary: Dermatophyte Infections
Very common superficial fungal infections
Often named for the body location targeted
Tinea capitis, corporis, cruris, pedis
Most common dermatophytes
T. tonsurans, rubrum, mentagrophytes and M. canis
Physical exam often characteristic, can confirm with KOH scraping and fungal culture
Treatment with topical/oral antifungals
Thank you for completing this module
• I hope that I was able to teach the subject clearly.• If you have any questions, write to me.
Survey
We would appreciate your feedback on this module. Click on the button below to complete a brief survey. Your responses and comments will be shared with the module’s author, the LSI EdTech team, and LSI curriculum leaders. We will use your feedback to improve future versions of the module.
The survey is both optional and anonymous and should take less than 5 minutes to complete.
Survey