FUNGAL SKIN INFECTIONS

Question 1

What is Tinea?

Answer 1

A superficial fungal infection of the skin caused by Dermatophytes

Question 2

What are dermatophytes?

Answer 2

A fungus that infects keratinous tissue and are able to invade the hair, skin and nails of a living host

Question 3

What is Tinea capitis?

Answer 3

A dermatophite fungal infection of the scalp
“Scalp ringworm”

Question 4

What is Tinea corporis?

Answer 4

A dermatophite fungal infection of the trunk/legs/arms
“Ring worm”

Question 5

What is Tinea pedis?

Answer 5

A dermatophite fungal infection of the feet
“Athlete’s foot”

Question 6

Most common cause of Tinea capitis?

Answer 6

Trichophyton tonsurans
May also be caused by microsporum canis acquired from cats or dogs

Question 7

Presentation of Tinea capitis?

Answer 7

Scaling and hair loss (scarring Alopecia mainly in children)
If untreated a raised, pustular, spongy/boggy mass called a Kerion may form

Question 8

Diagnosis of Tinea capitis?

Answer 8

Scalp scrapings
Wood’s lamp - microsporum canis shows green fluorescence

Question 9

Management of Tinea capitis?

Answer 9

Oral antifungal - terbinafine for Trichophyton tonsurans infections, griseofulvin for microsporum infections
Topical ketoconazole shampoo for the first 2 weeks to reduce transmission

Question 10

What can cause Tinea corporis?

Answer 10

Trichophyton rubrum
Trichophyton verrucosum - from contact with cattle

Question 11

How does Tinea corporis present?

Answer 11

As a well-defined annular, erythematous lesion with pustules and papules

Question 12

Management of Tinea corporis?

Answer 12

Oral fluconazole

Question 13

How does Tinea pedis present?

Answer 13

Itchy, peeling skin between the toes

Question 14

What is onychomycosis?

Answer 14

A fungal nail infection

Question 15

Is onychomycosis more likely to involve the toenails or fingernails?

Answer 15

Toenails

Question 16

Causative organisms of onychomycosis?

Answer 16

Dermatophites in 90% - mainly Trichophyton rubrum
Yeasts e.g. candida - 10%
Non-dermatophite moulds

Question 17

Risk factors for fungal nail infections?

Answer 17

Increasing age
diabetes mellitus
Psoriasis
Repeated nail trauma

Question 18

Features of fungal nail infections?

Answer 18

‘Unsightly’ nails
Thickened, rough, opaque nails

Question 19

Investigtaions for fungal nail infections?

Answer 19

Nail clippings and scrapings of the affected nail - microscopy&culture

Question 20

Management of mild, limited fungal nail infections?

Answer 20

Do not require Tx of asymptomatic

If dermatophyte or candida infection is confirmed…
If limited involvement - topical amorolfine 5% nail lacquer - 6 months for fingernails or 9-12 for toenails

Question 21

Management of extensive nail infection with dermatophytes?

Answer 21

Oral terbinafine 6 weeks-3 months for fingernails, or 3-6 months for toenails

Question 22

Management of extensive nail infection with candida?

Answer 22

Oral itraconazole
‘Pulsed’ weekly therapy

Question 23

What causes seborrheoic dermatitis?

Answer 23

Chronic dermatitis caused by an inflammatory reaction to a proliferation of Malassezia furfur

Question 24

Features of seborrheoic dermatitis?

Answer 24

Eczematous lesions on sebum-rich areas: scalp, periorbital, auricular, nasolabial folds
Otitis external and blepharitis may develop

Question 25

What disorders is seborrheoic keratosis associated with?

Answer 25

HIV
Parkinson’s disease

Question 26

Management of scalp seborrheoic dermatitis?

Answer 26

Ketoconazple 2% shampoo
OTC preparations containing zinc pyrithione (‘Head&Shoulders’) and tar (Neutrogena T/Gel) can be used
Selenium sulphide and topical corticosteroids may also be useful

Question 27

What is Pityriasis versicolor?

Answer 27

A superficial cutaneous fungal infection caused by malassezia furfur
Most commonly affects the trunk and causes hypopigmented/brown/pink patches with some scale and mild pruritus
Often more noticeable following a suntan

Question 28

Predisposing factors for pityriasis versicolor?

Answer 28

occurs in healthy individuals
immunosuppression
malnutrition
Cushing’s

Question 29

Management of pityriasis versicolor?

Answer 29

Topical antifungal - ketoconazole shampoos is most cost effective for large areas

Question 30

What is jock itch?

Answer 30

Tinea cruris
Tinea fungal infection in the groin, inner thighs and gluteal cleft

Question 31

What is Tinea incognito?

Answer 31

A fungal skin infection where the clinical appearance has been altered by inappropriate treatment, usually a topical steroid cream
The more steroid applied, the more extensive the fungal infection becomes, and the less recognisable

This is why you should never give topical steroids if considering a fungal infection