Diagnosis and Treatment of cutaneous fungal infections Flashcards
What is a common superficial skin infection that may become chronic?
Tinea versicolor
What is tinea versicolor?
Superficial yeast infection caused by Pityrosporum ovale aka Malassezia furur
Where is Malassezia normally found?
What does it do on our skin?
is normally found on human skin
Organism oxidizes fatty acids in the skin and inhibits tyrosinase in the melanocytes leading to loss of pigmentation
Pathogenesis of tinea versicolor?
Transformation of Malassezia from yeast cells to a pathogenic mycelial form is associated with the development of clinical disease
Not related to poor hygiene
Risk factors for tinea versicolor?
5
What age group is it most common in?
Most common in teens (>15) and young adults
Risk factors:
- heat,
- humidity,
- excessive sweating,
- use of topical skin oils,
- HIV infection
Tinea versicolor is characterized by what?
by hypopigmented lesions on the trunk that are asymptomatic
Clinical presentation of tinea versicolor?
Describe the lesions?
6
- Asymptomatic (sometimes can be pruritic)
- Velvety tan, pink or white macules
- Hypopigmented areas that do not tan with the rest of the skin
- 4-5 mm or confluent
- Trunk, upper arms, neck and groin
- Lesions may scale if scraped
Laboratory tests for tinea versicolor and what do they reveal?
Diagnosis?
3
Skin scrapings seen on KOH prep show budding spores and large hyphae “spaghetti and meatballs” (but a clinical diagnosis really)
Fungal culture not helpful
DDX:
- vitiligo,
- seborrheic dermatitis,
- pityriasis alba
Treatment fo choice for tinea versicolor?
To prevent reocurrence?
Selenium sulfide lotion or shampoo 2.5% (Rx) once daily for 7 days
maintenance therapy twice a month
Treatment options for tinea versicolor?
4
Ketoconazole (shampoo)
Selenium sulfide (lotion)
Intraconazole (PO)
Fluconazole (PO)
How long may it take for hypopigmented areas to return to normal?
COuld take months
80% of cases are recurrent
3 species of fungi that cause human infection (dermatophytes)?
Trichophyton
Microsporum
Epidermophyton
Dermatophytes grows where?
3
grow in the 1. skin, 2. hair and 3. nails leading to localized symptoms
What do dermatophytes digest?
What does this cause? 3
Dermatophytes digest keratin
Scaling
Nails thicken and crumble
Hair loss
Risk factors for tinea infectious
4
- warm, moist, occluded environments,
- family history,
- compromised immune system,
- alteration in normal flora
How is dermatophytes spread?
3
Humans, animals, inanimate objects
Where are Tinea infections located and what fungal species cause it?
5
Located in the stratum corneum
Caused by dermatophytes
- Trichophyton rubrum
- Trichophyton tonsurans
- Trichophyton mentagrophytes
- Mircrosporum canis
- Epidermophyton floccosum
Tinea is classified by it’s anatomic location:
Tinea corporis?
Tinea cruris?
Tinea pedis?
Tinea capitis?
Tinea unguium?
Body “ring worm”
Groin “jock itch”
Feet “athlete’s foot”
Scalp
Nails
Symptoms generally include what? 3
What could accompany these symptoms? 2
- pruritus,
- burning and
- stinging.
If inflammatory reaction may have
- erythema and
- vesicles in addition to the symptoms listed above
Laboratory evaluation of tinea infections?
7
- Microscopic evaluation
- Skin margin scraping and 3. KOH prep
- Fungal culture
- Takes 2 weeks
- Wood’s lamp
- Will identify Microsporum species
Tinea Corpis is find where?
3
What do the lesions look like? 3
How is it transmitted? 3
How should we treat it?
Face, limbs, trunk
- Ring shaped lesion with well-demarcated margins
- Central clearing
- Scaly, erythematous border
Transmitted by contact Humans, animals, sports equipment
Treat with a topical azole antifungal (apply 1-2 x daily for 2-4 weeks) continue therapy for a week after lesions clear
Tinea Cruris is found where? 2 spots.
Where is it not found?
Describe the lesions? 4
What is the hallmark sign?
Treatment?
Groin, inguinal folds
Spares the scrotum
- Borders distinct
- Lesions large,
- erythematous
- Macular with central clearing
Hallmark: pruritus with burning
Treatment: topical azole antifungal
TInea pedis is found where? 2
Descibe the lesions?
Treatment?
- Interdigital: scaling, maceration, fissures b/w toes
- Plantar: diffuse scaling of the soles
Acute vesicular: vesicles and bullae on the sole of the foot, great toe and instep
Treatment: topical azole antifungal (dry spray and allowing the area to be exposed to air)- also spray shoes
What do the lesions look like in tinea capitis?
5
- Inflamed
- scaly,
- alopecic,
- raised
patches - can have tender pustular nodules
