Cutaneous Fungal Infections

Tinea Corporis

Also called ringworm Red scaly ring with central clearing May involve trunk, arms, legs, neck

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 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

Diagnosis of Tinea Capitis

Diagnosis can be established by KOH and fungal culture -KOH will dissolve keratin but not fungi because their cell walls will remain intact. In a +KOH prep, the keratin will have dissolved, leaving the fungi visible Wood's lamp can identify certain dermatophytes via fluorescence: M. canis + fluorescence T. tonsurans - fluorescence

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

Tinea versicolor

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 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

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

Most common genera of fungi causing dermatophyte infections

Microsporum Trichophyton Epidermophyton

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

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

Clinical Manifestations of Tinea Capitis

Patches of alopecia with erythema and scaling Small black dots Diffuse dandruff Kerion formation due to severe inflammation

Tinea Capitis

Scalp Ringworm Common fungal infection in children, especially African American children The infection is based upon the fungus invading and attacking the hair shafts Trichophyton tonsurans= most common anthrophilic organism to cause tinea capitis in U.S. Microsporum canis=most common zoophilic organism to cause tinea capitis in U.S.

Ectothrix

Spores outside hair sheath M. canis is an ectothrix type of infection

Endothrix

Spores within the hair shaft T. Tonsurans is an example of endothrix where the spores are found

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

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.

Dermatophytes

fungi that digest keratin Geophilic: soil keratin Zoophilic: animal keratin Anthrophilic: human keratin Infection limited to keratin structures