skin 9: keratin layers- general Tinea

Question 1

Dermatophytes - Tineas

Answer 1

infections of the skin, nails or hair produced by keratinolytic (dermatophytic) fungi. Commonly referred to as tinea or “ringworm” infections.
generally named for the anatomic site affected

Question 2

Tinea classifications

Answer 2

Tinea capitis: ringworm of the scalp and hair
Tinea pedis: athlete’s foot
Tinea cruris: jock itch
Tinea unguium: oncychomycosis (nail infections)
Tinea manuum: ringworm of the hand
Tinea barbae: barber’s itch
Tinea corporis: ringworm of the smooth skin (i.e. trunk)
Tinea faciei: ringworm of the non-bearded areas of the face

Question 3

Tinea infection details

Answer 3

Keratin is required for growth
do not usually invade living tissue
Infections can occur at multiple sites.
Different organisms can cause the same tinea
presentation may vary with org/source
Disease is confined to the keratinized layers of the skin, primarily the epidermis.

Question 4

Tinea genera

Answer 4

Microsporum: Spindle-shaped macroconidia. Involves hair and skin.
Epidermophyton: Clavate-shaped macroconidia. Involves skin and nails.
Trichophyton: Elongated, pencil-shaped macroconidia. Involves hair, skin, and nails.

“Microsporum no nails, Epidermophyton no hair, Trichophyton everywhere”

Question 5

Tinea incidence

Answer 5

True incidence is unknown. It is estimated that the
prevalence is 20% of the global population. Studies report that 90% of all males have at least one bout.
The incidence and prevalence is lower in females.

Question 6

Tinea distribution??
cross-infection?
reservoir?

Answer 6

Tineas are globally distributed.
Cross-infection in families is 35-50% which is particularly important for infections in children.
Animals also act as reservoirs.

Question 7

Tinea (ringworm) is transmitted indirectly via ??

Answer 7

fallen hairs and desquamated epithelium more often than by direct bodily contact.

Sources of the organisms include: Contaminated barbershop instruments, hats, combs, bedding clothing, towels, furniture, theater seats, contaminated floors, infected mother-to-child, cats and dogs, cattle, rats, field mice, soil, etc.

Question 8

About 10% of the infectious material (w. tinea) was transferred from ??

Answer 8

contaminated textiles to sterile textiles during storage in a clothes basket simulation indicating a high infection risk during storage

While laundry wash temperature of 86oF will kill Candida spp., Washing at 140
oF will eliminated T. rubrum and C. albicans.

Question 9

Tinea Age and gender??
Seasonality??
risk factors??

Answer 9

More common in males and post-pubescents
Warmer months in general
Predisposing factors parallel that of pityriasis versicolor with the addition of obesity. Hydration and humidity are significant factors.

Question 10

Tinea pathogenesis: Dermatophyte colonization is limited to ??

Answer 10

the keratinized tissue of the epidermis

Although the cornified layers of the skin lack a specific immune response, both humoral and CMI immune systems and innate immunity act to limit invasion.

Question 11

major defenses against Tinea

Answer 11

• 2-macroglobulin keratinase inhibitor, unsaturated transferrin*, epidermal desquamation, lymphocytes, macrophages, epidermal Langerhans cells, dermal dendritic cells, neutrophils and mast cells.
• CMI is the major defense against dematophytic infections and fungal infections in general*

Question 12

Tinea Allergic manifestation

indicates what??

Answer 12

(dermatophytid (“id”))
sterile vesicle which can appear at a site distinct from the focus of infection.

This sign indicates a secondary inflammatory reaction as a result of an active CMI immune response.

would you rather have “bad” or mild infection? “bad!”: inflammatory infection implies immune response
-mild implies the organism as adapted to humans in order to self-preserve

Question 13

Tinea s/s: manifestations of mycotic agents are dependent on source of the organism

Answer 13

Geophilic: Normally inhabit the soil where they live on keratin that is shed by animals

Zoophilic: Infect or are carried by animals, but they can also infect humans who are in close contact with animals

Anthropophilic: Species whose principle reservoirs are human nails, skin and hair. rarely infect animals and cannot survive in the soil.

Question 14

Acute vs. chronic dermatophytoses infections: etiology

Answer 14

Acute: Geophilic or zoophilic species
Chronic: Anthropophilic species

Question 15

Acute vs. chronic dermatophytoses infections: inflammation

Answer 15

acute: severe
chronic: mild

Question 16

Acute vs. chronic dermatophytoses infections:s/s

Answer 16

acute: Erythema, vesicles, pruritus, pain
chronic: Erythema, scaling, pruritus

Question 17

Acute vs. chronic dermatophytoses infections: Spread of lesions

Answer 17

acute: Usually limited
chronic: Often extensive

Question 18

Acute vs. chronic dermatophytoses infections: duration

Answer 18

acute: weeks
chronic: months-years

Question 19

Acute vs. chronic dermatophytoses infections: DTH response

Answer 19

acute: high
chronic: low

Question 20

Acute vs. chronic dermatophytoses infections: prognosis (response to tx)

Answer 20

acute: good
chronic: poor

Question 21

Acute vs. chronic dermatophytoses infections:: recurrence

Answer 21

acute: rare
chronic: frequent

Question 22

Dermatophyte/Tinea dx: made by ??

problems??

Answer 22

taking skin scrapings for microscopy and culture.

Because of misdx, scrapings to make the dx have often been delayed for months.
If steroid cream has recently been applied, there is little surface scale to scrape off so results: inadequate or negative. A few days after stopping the steroid cream, the rash becomes very inflamed and more fungal elements may be seen on microscopy than usual. The responsible organism generally grows promptly in culture.

Question 23

Tinea office/lab tests

Answer 23

Wood’s lamp.
KOH prep of hair, skin, or nail scrapings.(Cellufluor white aids in staining). Culture hair skin, or nail scrapings on Dermatophyte Test Medium or Sabouraud-glucose agar containing chloramphenicol and cycloheximide.
(when too deep to use Wood’s lamp)

Question 24

Dermatophytes that fluoresce apple to blue green w. Wood’s lamp

Answer 24

Microsporum and superficial Pityriasis (Mala. furfur)

Question 25

Dermatophytes that fluoresce a brilliant coral red w. Wood’s lamp

Answer 25

Erythrasma, caused by the bacterium Corynebacterium minutissimum

(in a brown, scaly rash in the scrotum or axilla)

Question 26

Dermatophytes that do not fluoresce fluoresce w. Wood’s lamp

Answer 26

tinea cruris or cutaneous candidal infections

a brown, scaly rash in the scrotum or axilla

Question 27

Differentials for Annular Skin Eruptions, OR “All Rings Aren’t Ringworm”

Answer 27

Fungal eruptions are one of the most common causes of ring shaped eruptions, however, there are at least 24 other disorders that can result in rings on the skin.

Question 28

In general, in classic ringworm, there is ??

Answer 28

an annular lesion with an active border that exhibits erythema and scaling; however, there can also be significant inflammation, vesicles or minimal inflammation.
presentation in part depends on the source of the organism.

Question 29

how to dx Tineas

Answer 29

No findings are pathognomonic for superficial tinea infections, thus lab testing needed to confirm dx

locationof the lesions also can help ID org

Question 30

A dermatophytosis can most likely be ruled out if a patient has ??
In this situation, the more probable diagnosis is a ??

Answer 30

mucosal involvement with an adjacent red, scaly skin rash.

candidal infection such as perlèche (if single or multiple fissures are present in the corners of the mouth) or vulvovaginitis or balanitis (if lesions are present in the genital mucosa).

Question 31

Tinea ddx: Infectious Etiology.

Answer 31

Impetigo, 
coalesced HSV lesions, 
lyme borreliosis (erythema migrans), 
secondary syphilitic lesions, 
tuberculoid leprosy, 
HPV coalesced papules (verruga vulgaris).

Question 32

Tinea ddx: Papulosquamous diseases.

Answer 32

Pityriasis rosea (cause unknown thought to be a virus),
eczema (cause unknown but many patients are atopic),
psoriasis (cause unknown),
lichen planus (cause unknown but may be drug related),
urticaria (multiple causes), erythema multiforme (viral infections, e.g. HSV, and many drugs),
drug-induced eruptions, SLE, sarcoidosis, etc.

Question 33

Tinea incognito: tinea when ?? (“tinea in disguise”)

Answer 33

clinical appearance has been altered by inappropriate treatment, usually a topical steroid cream.
initial improvement–>spread of the organisms due to local conditions of immunosuppression and an associated skin discoloration.

Question 34

Compared with an untreated tinea, tinea incognito: ??

Answer 34

Has a less raised margin, is less scaly, more pustular, more extensive, and more irritable.
may also be secondary changes caused by long term use of a topical steroid such as: Atrophy (thin skin, stretch marks [striae] in the skin folds); purpura and telangiectasia (broken blood vessels).

Question 35

Tinea tx

Answer 35

Remove infected and dead epithelial structure. Apply topical (palliative or antifungal) agents (depends on host’s reaction to fungus and area involved).

Question 36

Tinea considerations for choice of antifungal agent include ??

Answer 36

type of infection
location of infection
severity of infection
age
sex
occupation of patient
overall patient health
compliance potential
cost

Question 37

Tinea solution tx

Answer 37

Solutions include potassium permanganate 1:5,000, salicylic acid or 20% sodium hyposulfite. Gentian violet (vaginal candidiasis, oral thrush).

Question 38

Tinea ointment/powder tx

Answer 38

Ointments at night, and powders by day include Whitfield’s (salicylic acid and benzoic acid), sulfur, tolnaftate (Tinactin)R, DesenexR (undecylenic acid or zinc undecylenate), haloprogin, clotrimazole (Mycelex)R, griseofulvin, imidazole derivatives, naftin.

Question 39

tx for severe dermatophytic infections

Answer 39

lamisil, itraconzole griseofulvin or ketoconazole is administered orally.

Question 40

tinea px

Answer 40

Will vary upon the site, severity of infection, underlying disease, and heredity.