Dermatology/ Superficial Fungal Infections

Question 1

How can superficial fungal infections be diagnosed in the office using microscopy?

Answer 1

• Combine loose hair, scale, or subungual debris with 1-2 drops of 10%-20% KOH on a slide.
• Gently heat the slide and look for septate, branching, rod-shaped fungal elements (hyphae).

Question 2

What is a dermatophyte?

Answer 2

A fungus capable of living on the keratin found in hair, skin, and nails

Question 3

What three genera of fungi are collectively referred to as dermatophytes?

Answer 3

1. Microsporum
2. Trichophyton
3. Epidermophyton

Question 4

Which dermatophyte is the most common cause of superficial fungal infections?

Answer 4

Trichophyton rubrum

Question 5

Tinea capitis is a fungal infection … of

Answer 5

Scalp

Question 6

Tinea faciei is a fungal infection of ….

Answer 6

face

Question 7

Tinea barbae is fungal infection of the …

Answer 7

beard

Question 8

Tinea corporis is fungal infection of the …

Answer 8

trunk and extremities

Question 9

Tinea cruris is fungal infection of the …

Answer 9

Groin

Question 10

Tinea manuum is fungal infection of the …

Answer 10

Hands

Question 11

Tinea pedis is fungal infection of the …

Answer 11

feet

Question 12

Tinea unguim is fungal infection of the …

Answer 12

nails

Question 13

How does tinea corporis (ringworm) classically present?

Answer 13

• Well-demarcated scaling plaque with a red, elevated, advancing border and an area of central clearing
• may include pustules and vesicles at the margins

Question 14

What is the most common cause of tinea capitis in the United States?

Answer 14

Trichophyton tonsurans infections

Question 15

Describe the four classic clinical presentations of tinea capitis.

Answer 15

1. Seborrheic: scaly dandruff
2. Black-dot: patches of hair loss due to breakage at scalp surface
3. Kerion: tender, boggy scalp mass with enlarged posterior cervical lymph nodes
4. Favus: oval patches of hair loss with golden crust

Question 16

What is the preferred treatment for tinea capitis?

Answer 16

Oral griseofulvin for at least 4 weeks

Question 17

Describe the three clinical patterns of tinea pedis.

Answer 17

1. Interdigital: scaling in web spaces between toes
2. Moccasin-type: scaling on soles and lateral feet
3. Inflammatory/vesiculobullous: vesicles on lateral aspect of feet

Question 18

What type of tinea infection is often associated with a dermatophytid reaction (id reaction = acute cutaneous reaction at distant site)?

Answer 18

Tinea pedis. It can result in a generalized immunologic reaction producing a vesicular eruption at distant sites (ie, hand dermatitis) that resolves with treatment of the primary infection.

Question 19

How is tinea unguium treated?

Answer 19

Griseofulvin, Itraconazole, or Terbinafine

Question 20

Excluding tinea capitis and tinea unguium, what is an appropriate treatment approach for most tinea infections?

Answer 20

Topical therapy with fungicidal allylamines (terbinafine or naftifine)

Question 21

What are the potential complications of using combined steroid-antifungal agents?

Answer 21

• skin atrophy
• steroid-induced acne
• striae

Question 22

What are the nondermatophyte organisms that typically cause tinea versicolor?

Answer 22

• Pityrosporum orbiculare or Malassezia furfur

Question 23

How does tinea versicolor present?

Answer 23

Hypopigmented or hyperpigmented erythematous macules with fine scale predominantly on the trunk

Question 24

What is seen with a KOH preparation of tinea versicolor?

Answer 24

A “spaghetti and meatball” pattern with short hyphae and yeast

Question 25

Describe the clinical patterns of Candidal intertrigo

Answer 25

Well-demarcated confluent pustules on an erythematous base with satellite pustules at the periphery within skin folds

Question 26

Describe the clinical patterns of Thrush

Answer 26

Adherent, cottage cheese-like plaques on the oral mucosa

Question 27

Describe the clinical patterns of Perleche

Answer 27

Angular cheilitis with erythema, fissuring at the corner of the mouth

Question 28

Clinical patterns of Paronychia

Answer 28

Infection of the proximal nail fold that presents with tenderness, erythema, and hyperkeratosis

Question 29

What is the preferred topical therapy for superficial candidal infections?

Answer 29

Nystatin

Question 30

What are the three most common causes of a red groin rash?

Answer 30

1. Tinea cruris (scale) 2. Candidal intertrigo (satellite pustules) 3. Erythrasma ( Corynebacterium that fluoresces coralred on Wood lamp exam)