Skin Fungal Infections Flashcards
What are superficial mycoses?
Fungi that colonize the keratinized outer layers of the skin, hair and nails
Usually asymptomatic, and only of cosmetic concern
What agent causes Pityriasis Versicolor?
Malassezia Furfur
Part of normal flora, found in areas of body rich in sebacous glands
What are the clinical features of Pityriasis Versicolor?
Hyperpigmented or hypopigmented macular lesions that scale readily - chalkybranny appearance
Occurs mot frequently on the upper torso, arms and abdomen
How is Pityriasis diagnosed and treated?
Direct microscopic examination of KOH treated skin, Wood’s lamp (lesions appear yellow)
Treatment - Selenium disulfide, hyposulfite, thiosulfate or salycylic acid. Ketoconazole 1% in cream
What is Tinea Nigra and what agent causes the infection?
Superficial fungal infection of the stratum corneum
Hortaea werneckii
What is the clinical presentation of Tinea Nigra?
Solitary, irregular, pigmented macule usually on the palms or soles
No scaling or invasion of hair follicles
How is Tinea Nigra diagnosed and treated?
KOH-treated scraping
Azole cream
What are cutaneous mycoses and what is the name of the organisms that cause these infections?
Infections that extend deeper into the epidermis, as well as invasive hair and nail diseases
Dermatophytes
Also referred to as ringworm or tinea
How are dermatophyte infections clinically classified?
Location
Tinea Capitis - head
Tinea corporis - smooth or glabrous skin
etc.
What is the clinical presentation of Tinea Capitis?
Hair becomes grayish, dull and brittle due to ectothrix invasion of hair, hair breaks off near the base
More common in prepubescent children
How do tinea infections present generally on the body?
Itchy, red, scaling or fissuring of the skin
Ring with irregular borders and a cleared central area may occur
What are dermatophytids?
Allergic reactions to dermatophyte infections that lead to lesions at different sites from the infection
What is the treatment for tinea infections?
Azole creams for local
Griseofulvin for early systemic infections
What is Wood’s lamp test?
Light that uses longwave UV light that makes fungus glow
Detects the presence of a fungal scalp or skin infection
What are subcutaneous fungal infections?
Infections that involve the deeper layres of the dermis, subcutaneous tissue or bone
Usually associated with some form of trauma (i.e. splinter, thorn, insect bite)
What is Sportrichosis?
Chronic infection characterized by nodular lesions of the cutaneous or subcutaneous tissues and adjacent lymphatics that suppurate, ulcerate and drain
What is the agent of lymphocutaneous sporotrichosis?
Sporothrix schenckii
Affects the skin and lymphatic system
Rose gardener’s disease
What are the clinical features of lymphocutaneous sporotrichosis?
Nodular and ulcerative lesions that develop along lymphatics and drain the primary site of inoculation
No systemic symptoms, despite lymph node involvement
How is S. Schenckii diagnosed?
KOH stain demonstrates “cigar-shaped” budding
Asteroid bodies - star shaped rays of eosinophilic material
What is the treatment for an S. schenckii infection?
Potassium iodide
Amphotericin B
What is Chromoblastomycosis?
Chronic infection of the skin characterized by the development of cauliflower-like lesions
Often seen in workers injured with woods
What agent causes Chromoblastomycosis?
Fonsecaea pedrosi
Dematiaceous fungi
How is chromoblastomycosis diagnosed and treated?
Presence of pigmented fungi in tissue sections or pus, sclerotic bodies
Treatment - excision, flucytosine
What are medlar bodies?
Copper-colored spherical yeast in tissue culture
What is Phaeohyphomycosis?
Heterogenous group of subcutaneous fungal infections characterized by the presence of darkly-pigemented fungal elements
What can phaeohyphomycosis cause?
Chronic paranasal sinus
Prosthetic valve endocarditis
Keratomycosis
Widely disseminated infections
How is phaeohyphomycosis diagnosed and treated?
Periodic acid-Schiff or methenamine silver stain
Treatment: surgical resection, Amphotericin B, Oral ketoconazole and itraconazole
What is fungal mycetoma?
Clinical syndrome characterized by tumefaction, draining sinuses, and sclerotia.
May progress to maduromycosis
What is maduromycosis?
Madura foot deforming infection on the foot or hand
What is the most common etiological agent of fungal mycetoma?
Petriellidium boydii
How is fungal mycetoma diagnosed and treated?
Macroscopic examination of sclerotia
Difficult to treat, amputation may be necessary
