Dermatophyte fungal infections

Question 1

Hair invasion types

Answer 1

Endothrix meaning fungal hyphae inside the hair shaft vs. exothrix meaning fungal hyphae inside the hair shaft and on the hair itself

Question 2

Classification of dermatophyte infections

Answer 2

All ringworm fungi: Microsporum, Trichophyton, and Epidermophyton

Question 3

Wet mount prep

Answer 3

For skin sample: heat up and then can look at it
For nail: can be left with KOH for 24hrs prior to examining
For hair: no need to prep it, just look under scope

Question 4

Mosaic artifact

Answer 4

lipid droplets in a line between cells that can look like hyphae, will disappear with more heat and presssure

Question 5

What type of hyphase in dermatophyte infection

Answer 5

branching hyphae

Question 6

Wood’s light examination

Answer 6

On hair:
- microsporum infection and trichophyton floresce blue-green to pale green
On skin:
- tinea versicolor turns white-yello
- Bacterium infection Corneybacterium minuteissiumum causing erythrasma turns bright coral

Question 7

Two-feet one hand syndrome

Answer 7

Usually caused by trichophyton rubrum

Question 8

Treatment of tinea pedis

Answer 8

• Lamisil (terbinafine) is very effective
• 2/2 ID reactions may need topical steroids
• if entire plantar surface affected, more difficult to tx

Question 9

Pitted keratolysis

Answer 9

Disease mimicking tinea pedis but Bacterial in etiology

on weight bearing part of soles of feet (slimy skin)

Question 10

Pitted keratolysis clinical presentation

Answer 10

circular pits &/ furrows

Question 11

Pitted keratolysis tx

Answer 11

Keep feet dry and antibacterial washing of feet

Question 12

Tinea cruris vs. candida of the groin

Answer 12

Tinea cruris typically presents as unilateral hald moon shaped plaque that does not extend onto scrotum.

Question 13

DDx of tinea cruris

Answer 13

Candida, intertrigo, erythrasma (scaly throughout not just at advancing border and a more red/brown)

Question 14

Erythrasma tx

Answer 14

Topical azole (but not ketoconazole) or PO erythromycin/clarithromycin

Question 15

Special fungal infections

Answer 15

Tinea verrucosum (very red and inflammed, caught from barn animals)
Tinea rubrum (granulomatous rxn)

Question 16

Is tinea capitis contagious

Answer 16

Yes, it can be spread by direct contact/through contaminated clothes unlike other fungal infections

Question 17

Kerion

Answer 17

severe inflammatory version of tinea capitis with a boggy, tumor like mass

Question 18

Lab medium for tinea capitis dx

Answer 18

Mycosels medium

Question 19

Clinical patterns of tinea capitis

Answer 19

Diffuse scale (DDx: seb/atopic derm, psoriasis)
Gray patch (DDx: seb/atopic derm, psoriasis)
Black dot (DDX: alopecia areata, trichotillomania)
Diffuse pustular (bacterial/dissecting folliculitis)
Kerion (DDx: abscess/neoplasia)

Question 20

Tineal capitis tx

Answer 20

Need oral antifungals (griseo is drug of choice in kids for 8-10 weeks)

Question 21

MCC of scalp ringworm

Answer 21

Trichophyton tonsurans (does not flouresce)

Question 22

Tinea amiantacea

Answer 22

Form of seb derm in kids with localized 2-8cm patches of large, brown polygonal shaped scale that adheres to the head and hair as it grows out

Question 23

Tinea barbae tx

Answer 23

oral antifungals

Question 24

Tinea barbae differentiation from bacterial folliculitis

Answer 24

Tinea usually starts in small area and grows, folliculitis outbreaks widely after shaving. And hair removal is easy and painless in tinea infection but difficult in folliculitis

Question 25

MOA of ntifungals

Answer 25

Azoles: P450 inhibitors
Griseo: fungistatic
Terbinafine: inhibits squalene epoxidase