Superficial:cutaneous mycoses

Thursday, January 19, 2012

SUPERFICIAL MYCOSES


WHAT ARE SUPERFICIAL MYCOSES?

Superficial mycoses are cosmetic fungal infections of the skin or shaft

No living tissue is invaded

No cellular response from the host

No pathological changes elicited

These infections are often so innocuous that patients are often unaware of their condition.


TINEA VERSICOLOR (Pityriasis versicolor)

Malassezia furfur: commonly known as “an-an”

Direct microscopic examination of alkali stain (KOH or PAS) treated with skin scrapings: “spaghetti and meatballs”

CONFIRMATION: cultures are not routinely done

ORGANISMS: lipophilic = requires fatty acid-supplemented http://missinglink.ucsf.edu


http://missinglink.ucsf.edu

http://missinglink.ucsf.edu

TINEA VERSICOLOR (Pityriasis versicolor)

Lesions occur most frequently on the upper torso, arms, and abdomen as discrete hyper – or hypopigmented macular lesions.

They scale very easily, giving the affected area a dry, or chalky appearance.

Sometimes, lesions appeared to be elevated and folliculitis may occur if hair follicles were involved.

http://dermimages.med.jhmi.edu






TREATMENT

1% selenium sulfide applied every other day for 15 minutes and then washed off


TINEA NIGRA(Exophiala werneckii)

usually asymptomatic and consist of well demarcated macular lesions (discolored spots on the skin that are not raised above the surface) that enlarge by peripheral extension

brown to black lesions = often seen at the sole of the foot or at the palmar surface of the hand (other body areas may also be affected)


TINEA NIGRA(Exophiala werneckii)

Diagnosis: darkly pigmented yeast like cells and hyphal fragments in microscopic examination of KOH tested scrapings taken from affected area

confirmatory test is made by culture


TREATMENTundecyclenic acid

keratolytic agent

Whitfield’s ointment (daily)

Tincture of iodine, 2% salicylic acid or 3% sulfur


WHITE PIEDRA(Trichosporon beigelii)

soft, white to light brown nodules

form on axillary, pubic, beard and scalp hair

relapse common


WHITE PIEDRA(Trichosporon beigelii)

hyaline septate hyphae that fragment into oval or rectangular arthroconida

blastospores can also occur at one or more points on the arthrospores


TREATMENT & DIAGNOSIS

DIAGNOSIS

direct microscopic exam of hairs

culture: asexual phase of the fungus

TREATMENT

shaving or cutting the infected hair

Topical fungicides: bichloride of mercury (1:200)

Benzoic and salicylic acid combinations

3% sulfur ointments


BLACK PIEDRA(Piedraia hortae)

hard black nodules formed around the scalp hair (carbonaceous; can house an asci)

thick-walled closely septate hyphe, with chlamydoconidia

growth is dimorphic – hyphae arthroconidia, and blastoconidia.


DIAGNOSIS & TREATMENT

DIAGNOSIS:

direct microscopic examination of affected hair

culture: Saborauds dextrose agar

TREATMENT

therapy: shaving and cutting the infected hair

topical fungicides, bichloride of mercury

Benzoic acid/salicylic acid combinations


BLACK VERSUS WHITE

CHARACTERISTIC BLACK PIEDRA WHITE PIEDRA

Etiology Piedraia hortae Trichosporon beigelii

Nodules

Over and around the hair shaft , hard, difficult to detach from the hair

On the surface of the hair shaft, softer, easy to separate from hair

Direct ExaminationsTightly packed dichotomous branched hyphae

Arthrospores and blastopores can be seen

Presence of asci Positive Negative


CUTANEOUS MYCOSES


CUTANEOUS MYCOSES : DERMATOPHYTESsuperficial fungal infections of the skin, hair and nails

may stimulate immune response

no living tissues are involved = generally restricted to the keratinized layers of the integument and its appendages

NOTE: a variety of pathological changes may occur in the host because of the presence of infectious agent and its metabolic product


CLASSIFICATION OF DERMATOPHYTES


REPRESENTATIVE DERMATOPHYTES


CLINICAL FEATURES OF DERMATOPHYTE INFECTIONS

SKIN DISEASE LOCATION OF LESIONS CLINICAL APPEARANCE

FUNGI MOST FREQUENTLY RESPONSIBLE

TINEA CORPORIS(ringworm) Non-hairy smooth skin

clinical patches with advancing red,

vesiculated border and central scaling =

pruritic

Microsporum canis, Trichophyton

mentagrophytes

TINEA PEDIS (athlete’s foot)

interdigital spaces on feet of persons wearing

shoes

acute: itching, red vesicular

chronic: itching, scaling, fissures

T. rubrumT. mentagrophytesEpidermophyton

floccosum

TINEA CRURIS (jock itch) groin

erythematousnscaling lesion in intertriginous

areas = pruritic

T. rubrumT. mentagrophytes

E. floccosum


CLINICAL FEATURES OF DERMATOPHYTE INFECTIONS

SKIN DISEASE LOCATION OF LESIONS CLINICAL APPEARANCE FUNGI MOST FREQUENTLY RESPONSIBLE

TINEA CAPITIS

scalp hair

ENDOTHRIX: fungus inside hair shaft

EXOTHRIX: fungus on surface of hair

circular bald patches with short hair stubs or broken hair within hair follicles = Mircosporum-infected hair fluoresce

M. canisT. tonsurans

TINEA BARBAE beard hair edematous, erythematous lesion


TINEA UNGUIUM (onychomycosis) nail

nails thickened or crumbling distally, discolored = usally

associated with Tinea pedis


E. floccosum


TINEA CAPITIS (ringworm of the scalp)


TINEA BARBAE


TINEA CORPORIS(ringworm)


TINEA CRURIS (jock itch)


TINEA PEDIS (athlete’s foot))


TINEA MANUUM


TINEA UNGUIUM (onychomycosis)


Microsporum audoinii

Tinea capitis = intercalary chlamydoconidium


Microsporum canis

Tinea capitis, corporis and barbae = pyriform shaped conidia


Microsporum cookei

saprophytic = may be found in animal hairs (dogs and rodents)


Microsporum ferrugineum

Tinea capitis, corporis = bamboo-shaped hyphae


Microsporum gypseum

Tinea capitis, corporis, favosa = ellipsoidal; 4-6 cells in macroconidia


Microsporum gallinae

white comb lesion in chicken = blunt tip; cylindrofusiform-shaped


Microsporum nanum

Tinea capitis, corporis = ringworm of pigs


Epidermophyton floccosum

Tinea cruris, pedis, unguium = rarely invades hair


Microsporum equinum

Tinea in horses = large chain of spores


Microsporum fulvum

Tinea capitis = bullet-shaped septa


Trichophyton mentagrophytes

all types of tinea = spiral hyphae “en grappe”


Trichophyton rubrum

all types of tinea = “en thyrse”


Trichophyton veruccosum

Tinea corporis, barbae = ringworm in cattle (culture requires inositol)


Trichophyton tonsurans

Tinea capitis, corporis - originates from aborigines


Trichophyton schoenleinii

Tinea capitis, favosa, corporisfavus = scutula (permanent hair loss)


Trichophyton violaceum

Tinea capitis, favosa, corporis = black dot (deep violet in culture)


Trichophyton concentricum

Tinea imbricata = resembles antler tip


ECOLOGICAL NICHE OF CUTANEOUS MYCOSES


COMPARING HAIR INFECTIONS


Health & Medicine

Superficial:cutaneous mycoses