Fungal Infections of the Skin

Question 1

Name the 3 most common superficial and cutaneous mycoses, caused by “ringworm”, Malassezia furfur, and Cladosporium werneckii.

Answer 1

Dermatophytosis, tinea versicolor, and tinea nigra, respectively.

Question 2

What does “tinea” mean?

Answer 2

refers to fungal skin infections, most commonly ringworm/dermatophytes

Question 3

Epidermophyton, trichophyton, and microsporum are the 3 main genera of what mycosis, and how are they most commonly spread?

Answer 3

Dermatophytosis; spread by direct contact, autoinnoculation, and fomites

Question 4

What kind of body structures do dermatophytes infect, and where do they tend to form chronic infections?

Answer 4

superficial keratinized structures (ex. skin, hair, nails); chronic infections in warm, humid areas

Question 5

What causes dermatophytid “id” vesicles to form on a patient’s fingers?

Answer 5

Hypersensitivity reaction to circulating fungal antigen

Question 6

Name where the following infections occur: tinea capitis, tinea corporis, tinea cruris, tinea pedis.

Answer 6

head, body, groin, foot

Question 7

What diagnostic test for dermayophytosis involves putting a drop of antigen under the patient’s skin and looking for a hypersensitivity reaction?

Answer 7

PPD with trichophytin

Question 8

What is the predominant symptom of ringworm?

Answer 8

Itching

Question 9

What skin infection involves overgrowth of a normal fungal flora on patients who are immunocompromised or have a genetic predisposition?

Answer 9

Tinea versicolor

Question 10

What is the predominant symptom of tinea versicolor?

Answer 10

superficial hypo-pigmentation

Question 11

Which cutaneous mycosis presents as a brown spot that may look like melanoma?

Answer 11

Tinea nigra

Question 12

Which cutaneous mycosis grows shiny black colonies when cultured on Sabouraud’s agar at room temperature?

Answer 12

Tinea nigra

Question 13

Why does the treatment of tinea nigra require both salicyclic acid and a topical azole?

Answer 13

The salicyclic acid is keratolytic - it breaks down the outer skin so that the azole can get to the fungus, which is growing between keratinized skin layers

Question 14

How are tinea nigra, sporotrichosis, chromomycosis, and mycetoma introduced into the body?

Answer 14

via trauma that exposes subcutaneous tissue (or just keratizined tissue layers for tinea nigra)

Question 15

Which subcutaneous mycosis, known as “rose-picker’s disease,” is thermally dimorphic?

Answer 15

Sporotrichosis

Question 16

Which fungus, also known as chromoblastomycosis or dermititis verrucosa, can best be prevented by wearing shoes?

Answer 16

Chromomycosis

Question 17

Which subcutaneous mycosis forms granulomas, dark wart-like lesions, and crusting abscesses?

Answer 17

Chromomycosis

Question 18

Which subcutaneous mycosis forms abscesses, pus, colored granules, and granulomas that may extend to the bone?

Answer 18

Mycetoma

Question 19

What fungus can be mistaken for the bacteria actinomycosis on both microscopic and physical examination, but does not usually affect the face?

Answer 19

Mycetoma

Question 20

Which cutaneous mycosis can be diagnosed by PPD with trichophytin or by microsporum florescence under Wood’s lamp?

Answer 20

Dermatophytosis

Question 21

Which cutaneous fungus appears as thick septate branching hyphae with dark pigment after KOH mount?

Answer 21

Tinea nigra

Question 22

Which fungus appears as round or cigar-shaped budding yeasts in tissue biopsy, and as daisy-shaped conidia clusters in culture?

Answer 22

Sporotrichosis

Question 23

Which fungus appear as gray or black septate hyphae or conidia after KOH mount, or as dark brown round fungal cells inside leukocytes and giant cells after biopsy?

Answer 23

Chromomycosis/Chromoblastomycosis

Question 24

What rare infection can be caused by the soil fungi petriellidium or madurella?

Answer 24

Mycetoma

Question 25

Which 3 fungal infections are caused by organisms that usually live in soil?

Answer 25

Tinea nigra, chromomycosis, and mycetoma

Question 26

Which 2 subcutaneous mycoses are most likely to need surgical excision?

Answer 26

Chromoblastomycosis and mycetoma

Question 27

Is miconazole a topical or oral azole? What about griseofulvin, itraconazole, flucytosine, and selenium sulfide?

Answer 27

miconazole and selenium sulfide are usually topical; griseofulvin, itraconazole, and flucytosine are usually oral

Question 28

Which fungal infection often present as a painless, chronic ulcer that can develop into a pulmonary infection in a COPD patient, or meningitis in an immunosuppressed patient?

Answer 28

Sporotrichosis