Selling a Product or Service FUNGAL SKIN INFECTIONS II IHAB YOUNIS, M.D

Selling a Product or ServiceFUNGAL SKIN INFECTIONS

II

IHAB YOUNIS, M.D.

B. Cutaneous mycoses

• Infections that extend deeper into the epidermis, as well as hair and nail and caused by dermatophytes:– Tinea capitis – Tinea corporis  – Tinea manus – Tinea cruris – Tinea pedis – Tinea unguium

Tinea capitis

Etymology: L. [caput] head

• Tinea capitis is the most common pediatric dermatophyte infection worldwide

• The age predilection is believed to result from the presence of Malassezia furfur which is part of normal flora, and from the fungistatic properties of fatty acids of short and medium chains in postpubertal sebum

Hair invasion by dermatophytes

• Ectothrix invasion: Arthroconidia on the exterior of the hair shaft. The cuticle of the hair is destroyed and infected hairs fluoresce under a Wood’s lamp

• Endothrix hair invasion: Arthroconidia within the hair shaft only. The cuticle of the hair remains intact and infected hairs do not fluoresce under a Wood’s lamp

Ectothrix

Endothrix

Hair

Conidia

Hair

Conidia

Types

1-Scaly type:• Erythematous papule(s) around the hair shaft appear initially• Subsequently, one or several patches of scaly alopecia are seen where the hairs are broken just above the level of scalp• The hair looks lusterless as it is covered with arthrospores

2-Black dots type: • It is an endothrix infection, so hairs become notably fragile and break easily at the level of the scalp• The rest of the infected follicle looks like "black dots". Variable degrees of scaling and inflamm-ation are seen

3-Kerion : • Scattered painful pruritic pustular

folliculitis generally associated with regional lymphadenopathy and even fever

• In about 2-3 %, boggy nodules studded with broken hairs and purulent sticky material "kerion" appear• Scarring alopecia develops subsequently

4-Favus :Etymology: L. honeycomb • Dense masses of mycelium and epithelial debris forming yellowish cup-shaped crusts called scutula

• The scutulum develops at the surface of a hair follicle with the shaft in the center of the raised lesion

• Removal of these crusts reveals an oozing,moist, red base

• After a period of years, atrophy of the skin occurs leaving a cicatricial

alopecia and scarring

Tinea corporis (circinata)

Etiology• Affects the glabrous skin (ie, skin

regions except the scalp, groin, palms, and soles)

• T rubrum is the most common infectious agent in the world

• May result from contact with infected humans, animals, or inanimate objects (eg contact with sports facilities)

Clinically•Patients can be asymptomatic or

pruritic•Begins as an erythematous, scaly

plaque that may rapidly worsen and enlarge•Central resolution causes the lesion to be annular

• Scales, crusts, vesicles, and papules often develop, especially in the advancing border

• Infections due to zoophilic or geophilic dermatophytes may produce a more intense

inflammatory response than those caused by anthropophilic fungi

• Majocchi granuloma manifests as perifollicular, granulomatous

nodules typically in a distinct location, which is the lower two thirds of the leg in females

• Tinea imbricata (Imbricate= Ovelapping) is recognized clinically by its distinct scaly plaques arranged in concentric rings

Tinea CrurisCrus=Fold

Etiology• Transmitted by fomites, such as

contaminated towels or hotel bedroom sheets

• Autoinoculation occurs in 50 % of cases from tinea manuum or tinea pedis

• Risk factors for initial infection or reinfection include wearing tight-fitting or wet clothing or undergarments

• Tinea cruris is 3 times more common in men than in women

Clinically

• Patients complain of pruritus and rash in the groin. A history of previous episodes of a similar problem usually is elicited

• Large patches of erythema with central clearing are centered on the inguinal creases

• Lesions extend to the thighs , lower abdomen , pubic area & buttocks

• The penis & scrotum typically are spared

• Scales demarcate sharply the edge

• In acute infections, the rash may be moist and exudative

• Chronic infections typically are dry with a papular annular or arciform border and barely perceptible scale at the margin

• Chronic infections modified by the application of topical corticosteroids are more erythematous, less scaly, and may have follicular pustules

• In response to the infection, the active border has an increased epidermal cell proliferation with resultant scaling

• This creates a partial defense by way of shedding the infected skin and leaving new, healthy skin central to the advancing lesion

Tinea pedisEtymology: L. foot

Etiology

• The first report of tinea pedis was in 1908 by Whitfield, who, with Sabouraud, believed that tinea pedis is caused by the same organisms that produce tinea capitis and that it is a very rare infection !

• T rubrum being the most common cause worldwide

• Tinea pedis is thought to be the world's most common dermatophytosis. Rippon states that 70% of the population will be infected with tinea pedis at some time

• Childhood tinea pedis is rare

Risk factors

• A hot, humid, tropical environment • Prolonged use of occlusive footwear• Certain activities, such as swimming

and communal bathing, may also increase the risk of infection

• A defect may be present in the immune system, such as in cell-mediated immunity, that predisposes some individuals to tinea pedis, but this is not certain

Clinical types

1- Interdigital type

2- Chronic hyperkeratotic type(moccasin)

3-Inflammatory/vesicular type

1- Interdigital type:

• The most characteristic type, with erythema, maceration, fissuring, and scaling, most often between the fourth

and fifth toes & often is accompanied by pruritus

• The dorsal surface of the foot is usually clear, but some extension onto the plantar

surface of the foot may occur

2-Chronic hyperkeratotic type(moccasin)

• Chronic plantar erythema with slight scaling to diffuse hyperkeratosis that can be asymptomatic or pruritic• Both feet are usually affected

• Typically, the dorsal surface of the foot is clear, but, in severe cases, the condition may extend

onto the sides of the foot

3-Inflammatory/vesicular type:• Painful, pruritic vesicles or bullae• Most often on the instep or anterior plantar surface• After they rupture, scaling with erythema persists• Cellulitis,lymphangitis and adenopathy can complicate this type

• Dermatophytid reactions are associated with vesicular tinea pedis

• They mimic dyshidrosis (pompholyx) • They develop on the palmar surface

of one or both hands and/or the sides of the fingers as papules, vesicles, and,

occasionally, bullae or pustules may occur, often in a symmetrical fashion

• This is an allergy or hypersensitivity response to the infection on the foot, and it contains no fungal elements. The specific explanation of this phenomenon is still unclear

• Distinguishing between a dermatophytid reaction and dyshidrosis can be difficult. Therefore, a close inspection of the feet is necessary in patients with vesicular hand dermatoses

• The dermatophytid reaction resolves when the tinea pedis infection is treated, and treatment of the hands with topical steroids can hasten resolution

Tinea Manuum

  Etymology: L. hand  

• It is less common than tinea pedis• Erythema and hyperkeratosis of

the palms and fingers affecting the skin diffusely is the commonest variety, and is unilateral in about half

the cases• The accentuation of the flexural creases is a characteristic feature

• Other clinical variants include crescentic, exfoliating scales, circumscribed, vesicular patches, discrete, red papular and follicular scaly patches, and erythematous, scaly sheets on the dorsal surface of the hand. The latter forms are more likely to be zoophilic

• When the palms are infected, the feet are also commonly infected. A typical pattern of involvement is either one hand and both feet or both

hands and one foot

Tinea Barbae

Etiology• The mechanism that causes tinea barbae is

similar to that of tinea capitis. In both diseases, hair and hair follicles are invaded by fungi, producing an inflammatory response

• Currently, tinea barbae is infrequent around the world

• Tinea barbae was observed more frequently in the past when infection frequently was transmitted by barbers who used unsanitary razors, so it was termed barber's itch

1 -Inflammatory deep type (kerion)

• It is the most common clinical presentation

• caused primarily by zoophilic dermatophytes

• Most patients show solitary plaques or nodules; however, multiple plaques are relatively common

• Usually localized on the chin, cheeks, or neck, involvement of the upper lip is rare

• The characteristic lesion is an inflammatory reddish nodule with pustules and draining sinuses on the surface. Hairs are loose or broken, and depilation is easy

and painless

• Over time, the surface of the indurated nodule is covered by exudate and crust

• This variety of tinea barbae usually is associated with generalized symptoms, such as regional lymphadenopathy, malaise, and fever

2-Noninflammatory superficial type • Caused by anthropophilic

dermatophytes• This variety is less common and resembles bacterial folliculitis • Typically, erythematous patches

show an active border composed of papules, vesicles, and/or crusts. Hairs are broken next to the skin

Tinea Unguium and Onychomycosis

• Tinea unguium is clinically defined as a dermatophyte infection of the nailplate

• Onychomycosisincludes all infection of the nail caused by any fungus, including nondermatophytes and yeasts

Etiology

• It accounts for 20 % of all nail disease• Approximately 30 percent of patients

with dermatophyte infections on other parts of their body also have tinea unguium

• The most common dermatophytes causing tinea unguium worldwide are T. rubrum, T.mentagrophytes ,E. floccosum &Candida

Clinically

• Characteristically, infected nails coexist with normal-appearing nails

• Four types are recognized:– Distal subungual onychomycosis – Proximal subungual onychomycosis– White superficial onychomycosis – Candidal onychomycosis

Distal subungual onychomycosis

• It is the most common type and starts by invasion of the stratum corneum of the hyponychium and distal nail bed

• Infection moves proximally in the nail bed and invades the ventral surfaceof the nail plate

• Subungual hyperkeratosis results from a hyperproliferative reaction of the nail bed in response to the infection

• Invasion of the nail plate results in a progressively dystrophic nail unit

Proximal subungual onychomycosis

• It is the least common variant of onychomycosis

• It starts by fungal invasion of the stratum corneum of

the proximal nail fold and subsequently the nail plate

White superficial onychomycosis

• Well-delineated opaque "white islands" on the plate

• Patches coalesce to involve the entire nail plate. The nail becomes rough, soft and crumbly

Sporotrichosis

Etiology

• Caused by Sporothrix schenckii• The organism derives its name from R B

Schenck, who first reported the infection in 1898

• Sporothrix typically exists as a saprophytic mold on vegetative matter in humid climates worldwide

• It is a dimorphic fungus i.e. the organism exhibits mycelial forms at 25°C and a yeast form at 37°C

• Cutaneous infection often results from a puncture wound involving thorns or other plant matter

• Other more unusual reported causes include squirrel bites and trauma induced by liposuction

Clinically

1-Lymphocutaneous type• It is the most common presentation• Symptoms usually arise within 3 weeks

of injury• A subcutaneous nodule develops at the

site of inoculation and may ulcerate as the result of central abscess formation

• Satellite lesions form along the associated lymphatic chain and lymphadenopathy subsequently develops

2-Fixed (nonlymphatic) type:

• scaly, acneform, verrucous or ulcerative nodule that remains localized

• Satellite lesions and lymphadeno- pathy do not occur in this form

3-Disseminated type Can result in pyelonephritis,

orchitis, mastitis, arthritis, synovitis, meningitis or osseous infection

Mycetoma(Madura foot)

Etiology

• Gill first described the disease in the Madura district of India in 1842

• In 1813, Pinoy described the mycetoma produced by actinomycetes (aerobic bacteria) and classified mycetomas as those produced by true fungi (eumycetoma) versus those due to aerobic bacteria (actinomycetoma). Both types have similar clinical findings

• Causative agents are implanted subcutaneously, usually after a penetrating injury

True fungi (eumycetoma) 40%

Filamentous bacteria (actinomycetoma) 60%

Dark grain:• Madurella mycetomatis• Madurella grisea• Leptosphaeria senegalensis• Curvularia lunata

Pale grain:• Scedospor. apiospermum• Neotestudina rosatii• Acremonium spp.

• Actinomadura madurae• Actinomadura pelletieri• Streptomyces somaliensis• Nocardia brasiliensis• Nocardia otitidis-caviarum• Nocardia asteroides

Clinically

• The skin is usually darker and firmer than the surrounding areas

• Nodules, abscesses, and fistulae draining a clear viscous or purulent exudate can be seen

• Granules of the microorganisms (sulpher granules) may occasionally be seen The most common site is the feet

• In advanced cases, destruction of bone within an infected area may be almost complete, and gross deformity may result

Lab diagnosis of fungal infections

Clinical Material• Patients with suspected dermatophytosis of

skin: – any ointments or other local

applications present should first be removed with alcohol

– Using a blunt scalpel, firmly scrape the lesion, particularly at the advancing border. In cases of vesicular tinea pedis, the tops of any fresh vesicles should be removed as the fungus is often plentiful in the roof of the vesicle

• In patients with suspected dermatophytosis of nails:– The nail should be pared and

scraped using a blunt scalpel until the crumbling white degenerating portion is reached

– Any white keratin debris beneath the free edge of the nail should also be collected

• Up to 30% of suspicious material collected from nail specimens may be negative by either direct microscopy or culture

• Repeat collections should always be considered in cases of suspected dermatophytosis with negative laboratory reports

Direct Microscopy

• Skin Scrapings, nail scrapings and epilated hairs should be examined using 10% KOH

Culture

• Specimens should be inoculated onto primary isolation media, like Sabouraud's dextrose agar containing cycloheximide and incubated at 26-28C for 4 weeks. The growth of any dermatophyte is significant

Wood's lamp examination

• It consists of UV light of wavelength above 365nm filtered through glass which contains about 9% nickel oxide

• Value: generally of limited usefulness, because most dermatophytes currently seen do not fluoresce

• May have value in the following situations:– For diagnosing a brown, scaly rash

in the scrotum or axilla: erythrasma fluoresces a brilliant coral red, whereas tinea cruris or cutaneous candidal infections do not fluoresce

– For diagnosing tinea versicolor, which fluoresces pale yellow to white

– For diagnosing tinea capitis caused by two zoophilic Microsporum species that fluoresce blue-green

Histopathology

PAS stain: Spores & hyphae in the keratin

Tinea versico;or: Spaghetti & meat balls