fungals

Tinea Pedis: Moccasin Type

Also known as chronic hyperkeratotic type. Sharply marginated scale, distributed along lateral borders of feet, heels, and soles. At times, vesicles and erythema are present at the margins. Often associated with onychomycosis (nail fungal infection).

Tinea Corporis Tx

Annular lesion with central clearing is typical of tinea corporis Tx; begin wtih topical antifunglad (azoles or allylamines) Oral antifungals are indicated in the following situations: If there is a poor response to topical agents If an animal is the source of infection If eruptions involve a large surface area

Candidal Intertrigo: Basic Facts

Candidal intertrigo = candidiasis of large skin folds May arise in the following areas: Groin or armpits Between the buttocks *Under large pendulous breasts* Under overhanging abdominal folds KOH exam reveals pseudohyphae Burns more than itches

The KOH Exam Procedure

Clean and moisten skin with alcohol swab Collect scale with #15 scalpel blade Put scale on center of glass slide Add drop of KOH and coverslip; heat slide gently with flame to adequately dissolve keratin Microscopy: scan at 10X to locate hyphae; then study in detail at 40X if needed

Take Home Points

Cutaneous fungal infections are extremely common. There are three clinical patterns of tinea pedis infection: interdigital, moccasin, and vesiculobullous type. If it scales, scrape it! KOH examination is the easiest and most cost effective method used to diagnose fungal infections of the hair, skin, and nails. Fungal culture is important because it may be positive when KOH prep is negative, and is the only easily available method to definitively identify the organism. Culture is especially helpful in tinea corporis when the source of infection is not obvious (as opposed to tinea pedis).

dermatophyte

Dermatophytes cause infections of the skin, hair and nails. Some of these infections are known as ringworm or tinea. Toenail and fingernail infections are referred to as onychomycosis

predisposing factors

Diabetes mellitus Hot, humid weather Limited mobility Obesity All of the above

possible pitfalls of KOH prep?

False negative KOH due to prior partial treatment with antifungals Misidentification of clothing fibers or lint as hyphae Possibility of mistaking lipid or cell membranes for hyphae (hyphae have parallel walls throughout and tend to be longer)

Tx

For all types of tinea pedis, hygiene and topical antifungals are effective first-line therapies Hygiene: Dry the area after bathing Change socks daily and alternate shoes worn Consider wearing open shoes such as sandals Use foot powder (available over the counter) to keep feet dry Topical antifungals: apply until tinea shows resolution, then *continue treatment for a minimum of two weeks* Imidazoles: Fungistatic *(azoles)* Examples: clotrimazole, miconazole, sulconazole, oxiconazole, ketoconazole (least activity against dermatophytes) *Allylamines*: Fungicidal Examples: terbinafine, butenafine, naftifine Ciclopirox: Fungicidal and fungistatic Example: Ciclopirox olamine For vesiculobullous: compresses in conjunction w/ antifungals may require an oral agent (terbinafine or itraconazole)

Tinea Pedis: Vesiculobullous Type

Grouped, 2-3 mm vesicles or bullae are seen, often on the arch or instep. They may be itchy or painful. Is a delayed hypersensitivity immune response to a dermatophyte.

versicolor Dx & Tx

KOH exam micro: hyphae (short) with spore aka *spaghetti and* *meatballs* Tx: antifungal shampoo - leave on skin for at least 10 minutes then rinse can use azole creams: daily or BID for 2 weeks oral (when large area involved: azole (ketoconazole can be used as one time dose - med is delivered via sweat ( so take and then exercise) avoid shower 6 hours after taking many relapse: if more than one relapse use manienance therapy: topicals are used 1-2x/week Ketoconazole shampoo Selenium sulfide (2.5%) lotion or shampoo Salicylic acid/sulfur bar Pyrithione zinc (bar or shampoo)

Dx Tinea

KOH: KOH microscopy is the easiest and most cost effective method used to diagnose fungal infections of the hair, skin, and nail. Proper technique requires training. Sensitivity is dependent on the operator's experience. KOH dissolves keratinocytes to allow easy viewing of hyphae. Heat is used to accelerate this reaction.

Complications of tinea pedis

Lower leg cellulitis (the most common risk factor for lower leg cellulitis in immunocompetent non-diabetics is tinea pedis, which creates a portal of entry for bacteria) Tinea corporis (from autoinoculation) Onychomycosis: a chronic fungal infection of the nailbed that tends to spread to other nails. *First line treatment: oral terbinafine or itraconazole*

Tinea Pedis: Moccasin Type w/ Hands

Moccasin type may present as "one hand, two feet" syndrome. Affected hand shows unilateral fine scaling, particularly in the creases (see below), and nails are often involved.

Tinea Pedis: Interdigital Type

Most common, presents with scaling and redness between the toes and may have associated maceration.

Tinea Versicolor - aka Pityriasis versicolor

NOT a dermatophytosis patho: Malassezia (yeast - nml to skin Well-demarcated, pink and tan (or hypo pigmented), macules and patches. Macules will grow, coalesce in an asymmetric distribution Visible scale is not often present, but when rubbed with a finger or scalpel blade, scale is readily seen *This is a diagnostic feature of tinea versicolor*Tinea versicolor Dx Evoked scale will disappear after treatment Tends to recur annually in summer

KOH micro

Parallel walls throughout the entire length Septated and branching hyphae

Erythema and scaling are present on the plantar surface and between the toes. What is it?

Tinea pedis ("athlete's foot") common fungal infection seen in developed countries, and is most commonly caused by the fungus *Trichophyton rubrum* Shoes provide an ideal environment for fungus to grow due to moisture Public showers, gyms, and swimming pools are common sources of infection It is difficult to permanently cure and may often recur There are three clinical patterns of infection: interdigital, moccasin, and vesiculobullous type

Take Home Points Con't

Tinea versicolor is characterized by well-demarcated, tan, salmon, or hypopigmented patches, occurring most commonly on the trunk. Topical treatment is usually appropriate as a first-line agent for tinea pedis, tinea corporis, and candidal intertrigo, however oral medications are called for when involvement is extensive, when tinea corporis is thought to have been transmitted by an animal, and in fungal infections of the nails. Fungal infections have high rates of recurrence after treatment, but maintaining a dry, clean skin environment is helpful for prevention. Monitoring for recurrence and maintenance treatments may be helpful in patients with recurrent infection.

candidal intertrigo tx & managment

nystatin ointment Topical anti-inflammatory -Low strength glucocorticoid preparations rapidly improves the itching and burning, but should be *stopped after one week* Systemic antifungal agents (used for infections resistant to topical treatment) Oral fluconazole, itraconazole, or ketoconazole Topical antifungal agents Polyenes and Imidazoles: nystatin, miconazole, clotrimazole, or econazole *Allylamines are not used to treat candida* Prevention Keep intertriginous areas dry, clean, and cool Encourage weight loss for obese patients Washing with benzoyl peroxide bar may reduce Candida colonization

Ringworm- tinea corporis

sharply marginated, erythematous annular lesion with central clearing and raised papulovesicular border with scaling. Dx: KOH - scrape red scaly margin can also get a culture to determine specific fungal species ( will take forever to grow 4-6 wks) Micro: tinea corporis (dermatophyte affecting trunk and limbs- mostly) Most prominent sx: itching asymmetric distribution A variant of this is tinea cruris or "jock itch", which has a similar presentation but appears in the groin