DERM: Fungal infections

Question 1

what causes tinea?

Answer 1

ringworm

Dermatophyte infection

Question 2

what are some clinical features of tinea?

Answer 2

Ringworm presents as an itchy rash that is erythematous, scaly and well demarcated.

• unilateral
• superficial layers of skin

TOM TIP: Check the toenails in someone presenting with ringworm, you may find they have a fungal nail infection that has spread to the skin.

Question 3

what is Tinea capitis?

Answer 3

refers to ringworm affecting the scalp (caput meaning head)

Question 4

what is Tinea pedis?

Answer 4

Tinea pedis refers to ringworm affecting the feet, also known as athletes foot (pedis meaning foot)

Question 5

what is Tinea cruris?

Answer 5

Tinea cruris refers to ringworm of the groin (cruris meaning leg)

Question 6

what is Tinea corporis?

Answer 6

Tinea corporis refers to ringworm on the body (corporis meaning body)

Question 7

what is Onychomycosis?

Answer 7

Onychomycosis refers to a fungal nail infection

Question 8

what is Tinea unguium?

Answer 8

nails

• Yellow discolouration
• Nails thicken and crumble

Question 9

what is Tinea incognito?

Answer 9

Tinea incognito refers to a more extensive and less well recognised fungal skin infection that results from the use of steroids to treat an initial fungal infection. This often occurs when the initial presentation of ringworm was misdiagnosed as dermatitis and a topical steroid was prescribed.

• Arises from treating tinea with corticosteroids
• Ill-defined lesions
• Less scaly

Question 10

how do you diagnose tinea?

Answer 10

• Skin scrapings
• hair/nail clippings

It is possible to scrape some of the scales off and send them for microscopy and culture to identify the causative organism and confirm the diagnosis.

Question 11

how do you treat tinea?

Answer 11

antifungals:

• Anti-fungal creams such as clotrimazole and miconazole
• Anti-fungal shampoo such as ketoconazole for tinea capitis
• Oral anti-fungal medications such as fluconazole, griseofulvin and itraconazole

Question 12

why should you try to avoid treating tinea with topical steroids?

Answer 12

Can cause tinea incognito

A mild topical steroid can help settle the inflammation and itching. A common combination is miconazole 2% and hydrocortisone 1% cream (Daktacort).

Question 13

what is candidiasis?

Answer 13

Candidiasis is a common fungal infection, resulting from yeasts of the genus Candida, mostly C albicans.

It is commonly called “thrush”. It is more common in immunosuppressed patients and those with diabetes.

Question 14

what are some risk factors. for candidiasis?

Answer 14

• Infant/elderly
• Warm environment
• Occlusion e.g. plastic underwear, dentures
• High oestrogen contraceptive pill
• Pregnancy
• Diabetes mellitus
• Iron deficiency
• immunocompromised

Question 15

how do you diagnose candidiasis?

Answer 15

• Skin scrapings
• hair/nail clippings

HOWEVER candida can live on a skin/mucosal surface without developing infection

Question 16

how do you treat candidiasis?

Answer 16

• Treat known triggers (e.g. immunosuppressive condition
  Warm, wet environment
  Poor hygiene in affected areas)
• Topical antifungals
  E.g. terbinafine
• Oral antifungal – severe, widespread or nail infections
  E.g. Itraconazole
• Avoid use of topical steroids
  Can cause tinea incognito

Question 17

what is a complication of. candidiasis?

Answer 17

invasive candidiasis

• Spread of candida through bloodstream and infection of internal organs and tissues
• Occurs in severely immuno-compromised or unwell individuals
• Rare compared to thrush and other non-systemic candidal infection

Question 18

what is pityriasis versicolor?

Answer 18

A superficial fungal infection of the stratum corneum, due to dimorphic yeasts of the genus Malassezia, leading to hypo- or hyperpigmented macular lesions on seborrhoeic areas of the trunk.

Question 19

what causes pityriasis versicolor?

Answer 19

Malassezia Furfur

Question 20

what are general clinical features of pityriasis versicolor?

Answer 20

• usually asymptomatic
• hyper- or hypopigmented patchers of skin
• usually upper trunk (chest and back)
• do not tan on sun exposure

Question 21

how do you diagnose pityriasis versicolor?

Answer 21

Microscopy
Fungal culture
Skin biopsy

Question 22

how do you treat pityriasis versicolor?

Answer 22

• Treat known triggers
• Topical antifungals
  E.g. terbinafine
• Oral antifungal – severe or widespread E.g. Itraconazole
• Avoid use of topical steroids - Can cause tinea incognito