Cutaneous Mycoses

Question 1

List the common cutaneous mycoses (3)

Answer 1

Malassezia furfur
Dermatophytes
Sporothrix

Question 2

What disease does Malessezia cause?

Answer 2

Pityriasis Versicolor

Question 3

What does Malessezia look like?

Answer 3

On KOH prep of skin scrapings, you will see a characteristic spaghetti and meatball appearance.

Diagnostic

Question 4

What environments does Malessezia prefer?

Answer 4

Hot and Humind

It is most active/disease causing in the humidity

Part of normal skin flora

Question 5

Malessezia infection presentation

Answer 5

In healthy people, it causes Pityriasis Versicolor (hypo or hyper pigmented patches)

• just a dermatologic annoyance
• it isn’t even itchy
• patches are on back and chest (esp in people who spend a lot of time in the sun)

Patches form due to lipid degradation which produces acids that damages melanocytes, causing pigmentation issues (Malessezia is lipophilic)

Fungus generally stays confined to skin - stays in stratum corneum (most superficial layer)

Question 6

Malessezia dissemination

Answer 6

In immunocompromised

Neonates that are receiving TPN (Total parenteral nutrition):

Along w/ TPN is a lipid infusion that travels through catheters into the body

Neonates in NICU receive this a lot

The fungus loves lipids and since the catheter allows access through the blood, the fungus can grow in the lipid transfusion and enter the body to cause sepsis and thrombocytopenia

Adults getting lipid transfusions have issues too - symptoms usually aren’t as severe though.

Question 7

Malessezia Tx

Answer 7

Topical selenium sulfide

Question 8

What fungi are included in the dermatophyte family?

Answer 8

Trichophyton

Epidermophyton

Microsporum

Question 9

What infections do dermatophytes cause?

Answer 9

Tinea (ringworm) infections - ring-shaped lesions

Tinea capitis - head and scalp

Tinea corporis - on body

Tinea cruris - Jock itch

Tinea pedis - Athlete’s foot

Question 10

Who is most at risk of dermatophyte infection?

Answer 10

Athletes - swimmers/wrestlers especially

Animals (Pets) can also be a source of transmission - esp in younger kids

Question 11

Tinea infection presentation

Answer 11

Dermatophytes live on skin. Plant themselves on skin and rarely actually invade.

Lesions are pruritic

Dermatophytes can also infect the nails (Onychomycosis)

Question 12

Tinea Tx

Answer 12

Topical azoles (clotrimazole)

For onychomycosis, Tx is more difficult. It requires an oral drug like Terbinafine.

For more severe Tinea or a nail infection that won’t go away step up the antifungals to Griseofulvin - it deposits in keratin-rich tissue like skin and nails

Griseofulvin has GI side effects and isn’t well-tolerated.

Question 13

Tinea dx

Answer 13

Through Hx/PE

Seeing hyphae with KOH Prep of skin scrapings to confirm

Question 14

Sporothrix transmission

Answer 14

Trauma

Classically contracted by cuts from thorns of a rose bush - Rose Gardener’s Disease

Also found on tree bark, bushes, and plants

Question 15

What does sporothrix look like?

Answer 15

Cigar-shaped budding yeast

Branching hyphae seen at 25C

Question 16

Sporothrix presentation

Answer 16

Get the cut - results in local pustule/ulcer at site of trauma

Further nodules can develop in ascending pattern along the path of draining lymphatics

Red bumps on skin

Question 17

Sporothrix diagnosis

Answer 17

Confirm with culture (gold standard)

Biopsy shows granulomas consisting of histiocytes, multi-nucleated Giant Cells and cigar-shaped budding yeast

Question 18

Lymphocutaneous Sporotrichosis (Sporothrix) Tx

Answer 18

Itraconazole

Another form of treatment is a saturated solution of KI (not used anymore)