Skin Infections Flashcards
Common types of cutaneous infections
Bacterial, viral, dermatophyte (fungal), treponema (syphilis), arthropod
Langerhans cell function
Immune cells of the epidermis responsible for antigen presentation to lymphocytes
Impetigo cause
Superficial bacterial infection, usually staph aureus or strep pyogenes
Impetigo location
Around mouth or perineum
Impetigo clinical characteristics
Crusted, “glazed” eroded papule to plaques, peripheral rim of scale, may be tender or asymptomatic, uncommon but can be bullous
Impetigo treatment
Topical or oral antibiotics
Impetigo histology
Subcorneal neutrophils and scattered gram-positive cocci
Cellulitis definition
Common but potentially serious bacterial skin and soft tissue infection
Cellulitis clinical characteristics
Edematous, erythematous, warm, sometimes taut/shiny localized plaque, uncommonly blisters on surface from edema, usually solitary with or without fever and systemic symptoms
Cellulitis initiation
May be initiated by skin injury
Cellulitis treatment
Systemic antibiotics, rest, elevation
Necrotizing fasciitis definition
Rare “flesh-eating bacteria” of the deeper tissue
Necrotizing fasciitis cause
Usually anaerobic bacteria or group A strep pyogenes
Necrotizing fasciitis clinical characteristics
Crepitus, purple, dusky, necrotic color with or without ulcers and bullae, associated with severe pain and systemic symptoms
Necrotizing fasciitis treatment
Emergency surgery, antibiotics
Staph scalded skin syndrome cause
Epidermolytic-toxin producing staph aureus
Staph scalded skin syndrome age affected
Infants and younger kids, possibly adults with decreased renal function or that are immunocompromised
Staph scalded skin syndrome clinical characteristics
Cleavage/split within epidermis, desquamative erythema in body folds, starts as a localized infection and becomes systemic, usually febrile, peeling perioral and body folds, no mucosal involvement
Staph scalded skin syndrome treatment
Systemic anti-staph antibiotic
Staph scalded skin syndrome histology
Subcorneal split without neutrophils or bacterial organisms
Herpes simplex virus clinical characteristics
Recurrent, painful, tingling vesicles on lips and around mouth, “fever blisters”, “cold sores”, genital erosions
Herpes simplex virus types
Two types - 1 more common oral and 2 more common genital
Herpes simplex virus treatment
Systemic antiviral if indicated, but recurrence is common
Herpes simplex virus histology
Cytopathic effect on keratinocytes, margination, multi nucleation, molding
Varicella zoster virus clinical characteristics
Multiple tender, pruritic, diffuse pink papules or vesicles, disseminated papules and vesicles
Varicella zoster virus associated symptoms
Systemic symptoms
Varicella zoster virus reactivation
Zoster or shingles
Shingles clinical characteristics
Dermatomal distribution of papules, vesicles, and plaques that are itchy and painful
Varicella zoster virus histology
Inflammatory cells, identical to HSV, cytopathic effect on keratinocytes, margination, multi nucleation, molding
Verruca causative agent
Human papillomavirus
Verruca subtypes
Vulgaris (common), palmoplantar (on soles of feet or palms), plana (flat), condyloma acuminate (genital)
Verruca vulgaris histology
Papillomatous epidermal hyperplasia with hyperkeratosis and hypergranulosis
Verruca treatments
Extensive - immunosuppression, not extensive - freezing, chemical destruction, topical immunomodulators or irritants
Verruca clinical characteristics
Thick warty papules and plaques
Molluscum contagiosum clinical characteristics
Papule with central umbilication, dome shaped, waxy surface, may be single or multiple, might be pruritic
Molluscum contagiosum location
Trunk, face, axillae, genital area
Molluscum contagiosum spreading
Spread by scratching, curdlike core can be expressed from center and spreads virus
Molluscum contagiosum causative agent
Pox virus
Molluscum contagiosum histology
Prominent infected keratinocytes with accumulation of Pox virus (aka Henderson-Patterson bodies)
Molluscum contagiosum treatment
Watchful waiting, curetting after topical anesthetic
Tinea causative agent
Dermatophyte infection, fungi feed on dead skin (trichophyton, microsporum, epidermophyton)
Tinea diagnosis
KOH stain, fungal culture if inconclusive
Tinea histology
Altered cornified layer with introcorneal neutrophils, special stains can reveal fungal hyphae within cornified layer
Tinea subtypes
Pedis (athlete’s foot), corporis (ringworm body), manuum (hands), cruris (jock itch groin), capitis (scalp), onychomycosis (nails), versicolor (pityrosporum)
Syphilis causative agent
Treponema pallidum
Syphillis clinical presentation
Painless, asymptomatic eruption of scaly papules on hands, feet, and trunk, subjective fevers and mild fatigue
Syphillis - primary
Solitary or multiple painless genital chancres
Syphillis - secondary
Rash and condyloma lata, systemic symptoms
Syphillis - tertiary
Gummas, aortitis, neurosyphilis
Syphillis - congenital
Stillbirth, acral bull/erosions, rhinitis, rhagades, deafness
Syphillis - secondary histology
Psoriasiform and lichenoid inflammation with abundant plasma cells
Scabies clinical characteristics
Very itchy rash, vesicles, papules, “moth-eaten” burrows
Scabies causative agents
Sarcoptes scabiei, human itch mite female burrows into epidermis and lays eggs
Scabies transmission
Close skin to skin contact
Scabies location
Hands, feet, waistline, genitals
Scabies treatment
Permethrin cream topically
Scabies histology
Can actually see the mite… EWWWWWW
