Superficial cutaneous and subcutaneous fungal infections

Question 1

Superficial mycoses

Answer 1

agents of superficial mycoses are fungi that colonize the keratinized outer layers of the skin, hair, and nails. infections caused by these organisms elicit little or no host immune response and are nondestructive and thus asymptomatic. They are usually of cosmetic concern only and are easy to diagnose and treat.

Question 2

Pityriasis versicolor

Answer 2

Asymptomiatic colonization of the stratum corneum. Pityriasis versicolor is a disease of healthy persons that occurs worldwide, but it is most prevalent in tropical and subtropical regions. Young adults are most commonly affected. Pityriasis versicolor has not been documented in animals. Human infection is thought to result from the direct or indirect transfer of infected keratinous material from one person to another.

Question 3

Pityriasis versicolor Etiological agent:

Answer 3

malassezia furfur

Question 4

Pityriasis versicolor Unique risk factor

Answer 4

condition that reduces the rate of desquamation, that is shedding of epidermal cells, predisposing factors; poor nutrition, excessive sweating and pregnant

Question 5

Pityriasis versicolor General characteristics, tissue affected and clinical features

Answer 5

General characteristics: a lipophilic, yeast like organisms. It is part of normal flora, found in areas of body rich in sebaceous glands

tissue: Skin

clinical features: hyper pigmented or hypopigmented macular lesions that scale readily, giving it chalkybranny appearance, that occurs most frequently on the upper torso, arms and abdomen.

Question 6

M. Furfur description

Answer 6

Dimorphic. Lipophilic, opportunistic, interfere with melanin production. Transient, superficial and scaly. Also associated with seborrheic dermatitis and dandruff.

upper trunk, arms, chest, shoulders, face and neck are most often involved, but any part can be affected.

Irregular, well demarcated patches of discoloration that may be raised and covered in fine scale.

NO host reaction occurs and the lesions are symptomatic with the exception of mild pruritus in severe cases.

Question 7

Diagnosis: pityriasis veresicolor

Answer 7

Diagnositc procedures: although not usually necessary for establishing the diagnosis, culture may be performed using synthetic mycologic media supplemented with olive oil. Microscopically, the colonies are compirsed of budding yeast like cells with occasional hyphae.

KOH treated

Woods lamp: pale yellow

Question 8

Pityriasis versicolor treatment

Answer 8

Preparation containing selneium disulfide, hyposulfite, thiosulfate or salicyclic acid, ketoconaozle.

Question 9

Tinea nigra: appearance

Answer 9

appears as a solitary, irregular, pigmented (brown to black) macule, usually on the palms or soles. There is no scaling or invasion of hair follicles, and the infection is not contagious.

Question 10

Tinea nigra: Considerations

Answer 10

Because of its superficial location, there is a little or no discomfort or host reaction. Because the lesion grossly may resemble a malignant melanoma, biopsy or local excision may be considered. Such invasive procedures may be avoided by a simple microscopic examination of skin scrapings of the affected area.

Question 11

Tinea nigra: laboratory diagnosis and tx

Answer 11

10 to 20% KOH treated

scraping yeast like cells with hyphal fragments

TX: with azole cream

Question 12

Cutaneous mycosis

Answer 12

involves diseases of the skin, ahir and nails. Generally affected keratnized layers of the itegument and its appendages. They can use keratin as nitrogen source. The organisms which participate in these infections are known as dermatophyte.

Question 13

tinea faciei

Answer 13

ringworm of the face

Question 14

tinea capitis

Answer 14

ringoworm head

highly contagious

hair becomes grayish, dull and brittle due to exctothrix invasion of hair, hair breaks off near the base of the shafts

more common in prepubescent children

t tonsurans is the principal agent of tinea capitiss in the united states

Question 15

tinea corpris

Answer 15

ringworm of body

Question 16

tinea manus

Answer 16

ringworm of hand

contact with another site of infection, particularly the feet or groin

direct contact with an infected animal or soil

Question 17

tinea pidea

Answer 17

ringworm of feet

Question 18

tidea unguium (oncherchyosis)

Answer 18

ringoworm of nails

candida: irregular boarder between the pink portion of the nail and the white outside edge of the nail when the nial has lifted from the nail bed. Larger portion of the nail is opaque, can be whitened or discolored to yellow or green. Discoloration underneath the nail may occur as a result of secondary infection.

Question 19

tinea cruris

Answer 19

ringworm of groin

Question 20

anthropophilic

Answer 20

associated with humans

Question 21

zoophilic

Answer 21

associated with animals

Question 22

geophilic

Answer 22

found in the soil

Question 23

microsporum

Answer 23

keratin of skin and hair

fusiform or spindle shape conidia

Question 24

epidermophyton

Answer 24

keratin of skin and nails

snow shoe or beaver’s tail macroconidia with thin smooth walls

Question 25

trichophyton

Answer 25

keratin of hair, skin, and nail

penic or cigar shaped microcondia more in number than macoconidia

Question 26

immunity of cutaneous mycosis

Answer 26

no classical humoral or cell mediated protective immunity

allergic reaction leads to lesions at different sites from the infection. these lesions are called dermatophytids or ids.

Question 27

diagnositcs features of cutaneous mycosis

Answer 27

KOH of hair or scalp scrapings

growth on speacialized media

wood’s lamp

Question 28

tx of cutaneous mycosis

Answer 28

local: azole
systemic: griseofulvin

Question 29

tidea unguium trichophyton rubrum

Answer 29

trichophyton rubrum most common etiological agent. Fluorescence yellow to green under wood’s lamp

finger nail infections cured more quickly than toenail infections.

Question 30

tinea ungium candida

Answer 30

candida: irregular boarder between the pink portion of the nail and the white outside edge of the nail when the nial has lifted from the nail bed. Larger portion of the nail is opaque, can be whitened or discolored to yellow or green. Discoloration underneath the nail may occur as a result of secondary infection.

Question 31

laboratory diagnosis of cutaneous mycosis and tx

Answer 31

KOH of the hair or scalp scrapings

growth on specialized media. Characteried by a specfic pattern of growth in culture and by production of macro conidia and micro conidia

miconazole, clotrimazole and econazole.

oral: griseofulfivn, itraconazole, fluconazole, and terbinafine.

Question 32

Woods lamp

Answer 32

light that uses long wave ultraviolet light. When an area of scalp that is infected with tinea (a type of ringworm fungus) is viewed under a wood’s light the fungus may glow. this test may be done to detect the presence of a fungal scalp or skin infection.

Question 33

Subcutaneous mycoses common features

Answer 33

fungal infections that are implanted by trauma. The infections initially involve the deeper layers of the dermis, subcutaneous tissue or bone.

they are associated with some form of trauma occurring at the site of infection before the lesions developed

the infections occur on parts of the body that are most prone to be traumatized

the etiological agents are usually organisms commonly found in the soil or on decaying vegetation

they all produce granuloma

Question 34

Sporotrichosis: gross and the five types of infection

Answer 34

chronic infection charactereized by nodular lesions of the cutaneous or subcutaneous tissues and adjacent lymphatics that suppurate, ulcerate, and drain. Sporothrichosis can be separated into five types of infection, lymphocutaneous, fixed cutannous, mucocutaenous, disseminated, and pulmonary.

Question 35

Lymphocutaenolus sporotrichosis Etioogy

Answer 35

Etiology: Sporothrix schenckii. Dimorphic (mold to yeast). Common in the USA. Fungus that aaffets the skin and lymphatic system.

Question 36

Lymphocutaenolus sporotrichosis: clinical features

Answer 36

nodular and ulcerative lesions that develop along lymphatics that drain the primary site of incoulation. Despite involvement of the lymph channel, is localized without fever or malaise and without involvement of the regional lymph nodes. those in the axilla or groin.

Question 37

Fixed cutanneous lesions

Answer 37

Fungus remains limited to the skin and does not involve the lymphatics

Question 38

Diagnosis of Sporothrix schenckii

Answer 38

Culture, skin tissue specimen presevered in 10% KOH show cigar shaped budding yeast form of S. Schenckii.

Asteroid bodies may be present. Star shaped with rays of an eosinophjillic material radiating from central yeast like cell or cells. The yeast like cell is basophilic, 3-5 um in diamter. The entire complex may be 10 to 15 um in diameter.

Question 39

TX of Sporothrix schenckii

Answer 39

potassium iodid (oral in milk) (cutaneous infection

amphotericin B (disseminated infection)

Question 40

Chromoblastomycosis etiology

Answer 40

dematiaceous (pigmented) fungi (phialophora and cladosporium). The most common agent is Fonsecaeea pedrosi. most common in tropical and subtropical regions.

Question 41

Chromoblastomycosis clinical features

Answer 41

see in workers injured with woods

characterized by the development of papules at the site of incoulation which over the years become verrucous (warty) crusted. At the progression of the lesion: appears to vegetate, “cauliflower like” appearance, it is characterized by the development of Verrucous (warty) nodules at the site of inoculation.

Question 42

Chromoblastomycosis DIagnosis and treatment

Answer 42

presence of pigmented fungi in tissue sections or pus. The thick walled cells are called sclerotic bodies or medlar bodies (copper colored spherical yeast). Culture

Surgical excision in the early stages. 5FU.

Question 43

Phaeohyphomycosis (subcutaneous fungal infection) description

Answer 43

Darkly pigmented fungal elements. Cerebral or subcutaneous infection. These fugni can also cause chronic paransal sinusitis, prosthetic valve endocarditis, keratomycosis and widely disseminated infections

Question 44

Phaeohyphomycosis Causative agents

Answer 44

numerous and varied. Dematiaceous hyphomycetes and most common and they rpoduce melanin in the cell wall

Question 45

Phaeohyphomycosis Diagnosis and tx

Answer 45

DX: periodic acid schiff or methenamine silver stain: dark walled hyphae

TX: surgical resection of well localized lesions. Amphotericin B, oral ketoconazole and itraconazole

Question 46

Fungal mycetoma clinical

Answer 46

tumefaction, draining sinuses and sclerotia (granules, grains). Maduromycosis, madura foot defroming infection on the foot or the hand may take years to develop. The infections start as small indurated subcutaneous papules. The tissue exudates white, yellow or black granules.

Question 47

Fungal mycetoma: etiology and SX

Answer 47

petriellidium boydii is the most common eumycotic mycetoma in the united states and europe.

SX: massive induration with draining sinuses

Question 48

Fungal mycetoma: DX and TX

Answer 48

DX: macroscopically examination fo sclerotia. Sclerotia are mounted in sterile salin and then crushed microscopically fungal hyphae with many intercalary swollen cell can be seen.

TX: difficult to treat with antimycotic drugs. Amputation is usually the final action.