Cutaneous and Subcu Mycoses - Stillwell

Question 1

mycosis

Answer 1

fungal infection

Question 2

superficial mycoses

Answer 2

-fungal infection limited to outer layer (ex. tinea versicolor)

Question 3

dermatophyte infection

Answer 3

• fungal infection requiring keratin growth
• superficial infections on dead part of skin
• spread by direct contact and fomites

Question 4

subcu mycoses

Answer 4

• fungal infection of dermis, subcu, muscle or fascia

- deeper tissues

Question 5

systemic mycoses

Answer 5

• fungal infection that enters through respiratory or GI tract –> spread to other organs
• dimorphic, opportunistic
• affect immunocompromised

Question 6

dimorphic

Answer 6

• fungal infection in yeast and mold form
• mold at room temp, yeast at body temp**
• candida is exception**

Question 7

mold

Answer 7

• fungal infection containing branching hyphae**
• septated with pores –> cytoplasmic connections
• called mycelium
• fillamentous hyphae (ex. aspergillus, fusarium, rhizopus)

Question 8

yeast

Answer 8

• single celled and reproduce by budding
• contain pseudohyphae** (no cytoplasmic connections)
• elongate and stick together
• pseudohyphae –> think CANDIDA**

Question 9

tinea

Answer 9

-fungal infection of outer part of skin (ringworm, athlete foot, jock itch)

Question 10

mycetoma

Answer 10

• fungal and bacterial infection of subcu tissue

- enter through skin releasing “grains” of microorganisms**

Question 11

chromoblastomycosis

Answer 11

• chronic subcu fungal infection of TROPICAL climates**

- sclerotic (medlar) bodies**

Question 12

onychomycosis

Answer 12

-fungal infection of toenails/fingernails

Question 13

superficial mycoses - Tinea (pityriasis) versicolor

Answer 13

• cause: malassezia yeast**
• on skin as normal flora; trouble in warm/humid environment
• hyper/hypopigmented** lesions
• azeliac acid produces scaling circles**
• worry about sepsis in immunocompromised**
• spaghetti and meatballs on KOH stain**
• fluoresces on woods lamp**
• tends to relapse

Question 14

superficial mycoses - seborrheic dermatitis

Answer 14

• cause: malessezia?? –> produce azeliac acid which irritates skin**
• immunocompromised, Parkinson’s, Down syndrome
• worse in winter**
• dandruff on skinfolds, eyebrows, nose**
• treat: topical azoles (antifungals)

Question 15

superficial mycoses - cutaneous candida

Answer 15

• cause: Candida albicans
• infectious when it outgrows normal flora (ex. following antibiotic use)**
• satellite lesions around intertrigo**
• more reddish than erythrasma (corneybacterium minuttismus - more brownish, no satellite lesions, fluoresces under woods)**
• treat with topical anti fungal
• contain pseudohyphae on KOH stain**

Question 16

Cutaneous mycoses - dermatophytes

Answer 16

• deeper infections of skin, hair, nails –> itching, pruritus
• 3 different mycoses –> 1. microsporum, epidermophyton, trichophyton**
• trichophyton rubrum (main) and mentagrophytes most common**
• direct contact, viable up to 15 months
• path: secrete proteases, elastases, and keratinases for virulence factors**
• treat: cell mediated immunity (type 4 hypersensitivity); use topical or systemic antifungals if bad enough
• hyphae or arthrospores on KOH stain

Question 17

types of dermatophyte infections - tinea aka ringworms

Answer 17

1. corporis - body
2. cruris (jock itch) - inguinal, perianal, perineum
3. pedis (athlete foot)
4. manum - hands
5. capitis - scalp; ectothrix (invade outside hair shaft, hair breaks above skin); endothrix (invade invade inside hair shaft, hair breaks at skin level –> black dot ringworm)
6. unguium (onychomycosis) - nails
7. faciei - face without hair
8. barbae - face/neck with hair
9. imbricata - tinea corporis in infants near tropics (waves of scales
10. incognito - fungal growth with bacterial infection due to corticosteroids (bad)

Question 18

subcutaneous mycoses - cutaneous sporotrichosis (sporothrix/rose Gardners)

Answer 18

• cause: dimorphic fungi in soil, rosebushes, hay, wood –> farmer, Gardner, cats, veterinarian
• enter through abrasions or lungs –> sever in immunocompromised causing pneumonia
• nodule lesions tracking up lymphatic chain**
• silver stain –> cigar lesions**; grows on fungal culture
• can see granulomas, fibrosis, necrosis on histo
• treat: itraconazole usually; amphotericin in immunocompromised

Question 19

subcutaneous mycoses - mycetoma (Madura foot)

Answer 19

• chronic subcu fungal and bacterial infection
• mainly farmers –> inoculated through splinter/thorn
• 70% of time lesions seen on foot
• sinus tracts full of “grains” of microorganisms** –> form tumor or plaque
• treat: debridement or amputation

Question 20

subcutaneous mycoses - chromoblastomycosis

Answer 20

• traumatic inoculation of fungi –> granulomatous response
• usually lower extremities
• high rate of secondary bacterial infection
• sclerotic (medlar, copper penny) bodies on KOH stain**
• dark molds on fungal culture
• treat: surgical removal/amputation

Question 21

systemic mycoses - cryptococcosis (cryptococcus neoformans)

Answer 21

• encapsulated yeast that lives in soil or rotting wood
• enter through inhalation (respiratory problems)
• cause meningitis –> loves to travel to brain
• disseminated form causes skin lesions in immunocompromised (ex. HIV with low CD4)
• GMS (silver) and mucicarime stain –> narrow base budding**
• treat: amphotericin B

Question 22

systemic mycoses - histoplasmosis (H. capsulatum)

Answer 22

• get from inhalation of spores
• pulmonary infection
• secondary immune rxn with erythema nodosum
• immunocompromised –> skin and non healing oral lesions **
• granulomas and macrophages/monocytes engorged with yeasts** - parasites in Macs**
• common in AR

Question 23

systemic mycoses - blastomycosis (B. dermatitidis)

Answer 23

• enter through lungs (pneumonia)
• nodules in lungs and lymphadenopathy
• plaque like lesions
• broad/wide based budding on silver stain**
• commin in AR

Question 24

systemic mycoses - coccidioidomycosis (C. immitus)

Answer 24

• inhale spores –> pulmonary infections
• immunocompromised –> loves to travel to brain
• spherules enclosing multiple spores on stain**

Question 25

systemic mycoses - Paracoccidioidomycosis (P. brasiliensis)

Answer 25

• pulmonary symptoms
• mulberry like lesions on lips/face**
• silver stain showing multiple buds of single yeast**
• treat: azoles or amphotericin B

Question 26

zygomycetes (mucormycosis)

Answer 26

• caused by multiple types of fungi (very severe)
• in uncontrolled diabetic or immunocompromised**
• nonseptate hyphae that branch at 90 degrees**
• get through inhalation of spores and skin abrasions
• black necrotic plaques/eschars** –> invade tissue and blood vessels
• hard to treat, resistant to voriconazole**

Question 27

aspergillosis (Aspergillus)

Answer 27

• colonize bronchiole tubes in lungs –> affect COPD patients**
• disseminate in immunocompromised causing skin lesions
• septate hyphae branch at 45 degrees on silver stain**
• gang sign fungus**
• voriconazole drug of choice**

Question 28

parasite - pediculosis

Answer 28

• infestation of lice
• spread by direct/sexual contact and fomites (ex. helmets)
• vectors of louse-borne typhus, trench fever, relapsing fever**
• cannot burrow, look for nits
  1. capitis - scalp region = head lice
  2. corporis - body = Vagabond’s disease
  3. pubis - pubic region = crabs

Question 29

parasite - scabies

Answer 29

• 7 year itch**
• due to burrowing mite (Sarcoptes scabiei) –> form tracts**
• allergic rxn to mites dying
• spread by direct/sexual contact or fomites
• b/w fingers, toes, hands, arms, waistline**
• symptoms/itch lasts for long time after treatment**
• treat: ivermectin

Question 30

parasite - chiggers (trombiculidae)

Answer 30

• small mites in forests or grasslands
• found on ankles and exposed areas**
• do not suck blood or burrow
• inject saliva/digestive enzymes that kill cells –> inflammatory response and itching**
• treatment: prevention, scratching makes it worse

Question 31

parasite - bedbugs (cimex)

Answer 31

• feed on human blood
• come out at night and bite**
• treat: hot steam cleaning

Question 32

parasite - myiasis (maggots/fly larvae)

Answer 32

• flies lay eggs on open wounds
• maggots/larvae usually only eat dead tissue (clean infection with sterile maggots)
• due to trauma or infected leg
• treat: lure with rotten meat

Question 33

parasite - cutaneous larva migrans** (Ancyclostoma braziliense)

Answer 33

• nematode larva of hookworms**
• found on beach in animal feces
• larvae burrow and crawl through human skin
• ground itch, creeping pruritic eruption**
• cannot live whole life in body or penetrate basement membrane (stay in epidermis)

Question 34

parasite - swimmers itch** - (cercarial dermatitis)

Answer 34

• schistosomes from infected birds or mammals that are released from snails in fresh/salt water**
• lesions after swimming (summer) –> allergic rxn to parasite
• cannot finish life cycle in humans and die
• treat: anti-itch and corticosteroids

Question 35

parasite - cutaneous leishmaniasis (oriental sore, delhi boil)

Answer 35

• transmitted by sandfly and is a zoonosis (animal–> human vector and vice versa)**
• in texas and middle east
• scar remains after healing
• soldier coming back from Iraq***
• amastigotes in monocytes with a nucleus and rod-shaped kinetoplasts**
• PCR also available