cutaneous fungal infections

Question 1

What is Tinea versicolor also known as?

Answer 1

• Pityriasis versicolor

Question 2

What is Tinea versicolor?

Answer 2

• common superficial skin infection that may become chronic
• superficial yeast infection caused by Pityrosporum ovale aka Malassezia furor
• Malassezia is normally found on human skin (overgrowth)
• organism oxidizes fatty acids in the skin and inhibits tyrosinase in the melanocytes leading to loss of pigmentation

Question 3

Pathogenesis of Malassezia?

Answer 3

transformation of Malassezia from yeast cells to a pathogenic mycelial form is assoc with the development of clinical disease
- not related to poor hygiene

Question 4

Who commonly gets Tinea versicolor and what are the risk factors?

Answer 4

• very common,
• mostly common in teens (>15), and young adults, athletes
• RFs: heat, humidity, excessive sweating, use of topical skin oils, HIV infection

Question 5

How is Tinea versicolor characterized?

Answer 5

• by hypo pigmented lesions on the trunk that are asymptomatic
• sometimes can be pruritic
• velvety tan, pink or white macules
• hypo pigmented areas that don’t tan with rest of the skin
• 4-5 mm or confluent
• Trunk, upper arms, neck and groin
• lesions may scale if scraped (looks like dry skin)

Question 6

Lab findings of tinea versicolor?

Answer 6

• skin scrapings seen on KOH prep show budding spores and large hyphae “spaghetti and meatballs” (KOH kills epithelial cells)
• fungal culture not helpful
• DDX: vitiligo, seborrheic dermatitis (seen in HIV), pityriasis alba

Question 7

Tx of Tinea versicolor?

Answer 7

DOC: Selenium sulfide lotion or shampoo 2.5% (Rx)

• apply once daily
• apply with a cotton ball, allow to dry 15 min prior to bathing
• once daily for 7 days
• to prevent recurrence maintenance therapy 2x a month (have chronic recurring condition)
• other txs:
  tablets: Fluconazole (Diflucan) -> 300 mg tablets or Intraconazole (sporanox) tablets 200 mg

or Ketoconazole shampoo

Question 8

Maintenance therapy for Tinea versicolor?

Answer 8

• up to 80% of cases will have recurrence in subsequent 2 years w/o maintenance therapy
• Selenium sulfide lotion or shampoo 2x monthly
• pt education: may take months for hypopigmented areas to normal (they may not ever)

Question 9

3 species of fungi that cause human infection? (dermatophytes)

Answer 9

• Trichophyton
• Microsporum
• Epidermophyton

Question 10

localized sxs of dermatophytes do to the fact that they grow in skin, hair and nails?

Answer 10

• digest keratin

so see scaling, nails thicken, and crumble and will see hair loss

Question 11

Risk factors for Tinea?

Answer 11

• warm, moist, occluded environments, family hx, compromised immune system, alteration in normal flora
• spread by contact: humans, animals, inanimate objects

Question 12

Where are Tinea infections located in the epidermis?

Answer 12

• in the stratum corneum (superficial 1/2) and are caused by a variety of fungal species
• caused by dermatophytes:
  Trichophyton rubrum
  Trichophyton tonsurans
  Trichophyton mentagrophytes
  Microsporum canis
  Epidermophyton floccosum

Question 13

Classification of Tinea?

Answer 13

• Tinea corporis: body “ring worm”
• Tinea cruris: groin “jock itch”
• Tinea pedis: feet “athlete’s foot”
• Tinea capitis: scalp
• Tinea unguium: nails

Question 14

sxs of a Tinea infection?

Answer 14

• generally include localized pruritus, burning and stinging

- if inflammatory reaction may have erythema and vesicles in addition to sxs listed above

Question 15

Dx of Tinea infection?

Answer 15

• microscopic eval: skin margin scraping and KOH prep
• fungal culture: takes 2 weeks (do when it is recurrent infection)
• Wood’s lamp: will ID microsporum species

Question 16

Tinea Corporis?

Answer 16

• Face, limbs, and trunk
  ring shaped lesion with well demarcated margins
• central clearing
• scaly, erythematous border
• transmitted by contact by humans, animals, sports equipment
  -tx: topical azole antifungal (apply 1-2 x daily for 2-4 weeks) continue for a week after lesions clear

Question 17

Tinea cruris?

Answer 17

• groin, inguinal folds, spares the scrotum
• borders distinct
• lesions are large, erythematous, macular with central clearing
• hallmark: pruritus with burning
  Tx: topical azole antifungal
  (Better to use powder, already a moist area)

Question 18

Tinea pedis?

Answer 18

interdigital: scaling, maceration, fissures b/t toes
plantar: diffuse scaling of soles
acute vesicular: vesicles and bull on the sole of foot, great toe and instep

tx: topical azole antifungal (dry spray, allow feet to be exposed to air)

Question 19

Tinea capitis?

Answer 19

• most cases in children
• inflamed scaly, alopecic patches
• diffuse scaling with round alopecic patches due to broken hair shafts
• tender, pustular nodules
• tx: griseofulvin for 8 weeks, or terbinafine for up to 4 weeks (cannot use topical therapy: must be systemic therapy)

Question 20

Tinea unguium

Answer 20

• also known as onychomycosis
• typically toenails but can affect fingernails as well
• oncholysis may occur
• infection usually moves distal to proximal
• usually asymptomatic
• tx with oral terbinafine (lamisal) 250 mg qday x 6 wks for fingernails and 12 weeks for toenails (have to have systemic tx)
  (monitor LFTs, and CBC)

alt: itraconazole (sporanox)
- are a variety of topical Rx meds that are available but they have limited efficacy (50%)
- systemic antifungals are very toxic and there are a lot of drug interactions -> just let go fungal infections in elderly sometimes

Question 21

Cutaneous candidiasis?

Answer 21

intertrigo: axillae, under breasts, groin, intergluteal folds
balantitis: glans penis

candidal folliculitis: follicular pustules

candidal paronychia: nail folds

Thrush: mouth and tongue

diaper dermatitis

** will be more inflamed and red compared to Tinea (this will be in a round pattern)

Question 22

RFs for candidiasis?

Answer 22

• infection
• recent abx therapy
• diabetes
• systemic and topical steroids
• immunosupression
• warm, moist conditions
• break in the skin

Question 23

Tx of candidiasis?

Answer 23

• Thrush: oral lozenge or swish and swallow -> nystatin, and clotrimazole

cutaneous:
powder for macerated areas (Nystatin)
topical clotrimazole (lotrimin), ketoconazole

-if failure of topical therapy: oral fluconazole (Diflucan)