This is a brief video on infestations of the skin and infectious diseases of the dermis and epidermis.

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ADDITIONAL TAGS:
Cellulitis
Bacterial skin infection → red tender plaque, often on lower leg
Might see streaks of lymphangitis to lymph nodes
Fever, high WBCs, tender lymph nodes, pain
Risk factors: trauma/wounds, systemic infxn, edema, inflammatory state, bug bites
Erysipelas
more superficial, shiny, demarcated cellulitis
Notable dermal lymphatic involvement, usually on legs or face
Impetigo
AKA impetigo contagiosum
Superficial bacterial skin infection
Epi: often in children (2-5 yo), spread among contacts
Abscess
Large mass, red, warm, tender
Can drain pus/fluid
Treat with incision and drainage
If pt has multiple abscesses, immunosuppression, or other cellulitis, treat with oral abx
Furuncle: small perifollicular abscess, (boil)
Folliculitis
Bacterial infection of hair follicles
Looks like small, red, pustules with pus
Usually caused by staph aureus
Staphylococcal scalded skin syndrome
Secretion of staph aureus toxin into blood causes systemic blisters
“Skin peels away in sheets
Necrotizing fasciitis
Bacterial infection of fascia, spreads quickly
Pain unproportional to physical exam findings
Secondary syphilis
Second stage/presentation of sexually transmitted infection syphilis caused by bacterium Treponema pallidum
Secondary syphilis presents with diffuse rash which frequently involves palms of hands, soles of fee
Dermatophytes
Named “tinea _____” for the site of infection
Tinea pedis (athlete’s foot) → foot
Shoes create moisture → infected in public gym, pools, showers
Scaling/redness
Often recurs
Three patterns: interdigital, vesiculobullous, and moccasin types
Can involve nails → onychomycosis (requires oral antifungals (terbinafine) bc poor access with topicals)
Treat with hygiene (change socks, foot powder for dryness) and topical antifungals (imidazoles, allylamines, ciclopirox)
Can lead to lower leg cellulitis (fungal infxn creates portal of entry for bacteria)
Tinea corporis (ringworm) → trunk and limbs
Ring shaped lesion with central clearing → “ringworm”
Causes itching, affects all ages, often asymmetric
Treat similar to tinea pedis, use oral antifungals (terbinafine and fluconazole in severe cases)
Tinea cruris is similar in groin area
Tinea capitis → scalp and hair
Tinea (pityriasis) versicolor
AKA dermatomycosis furfuracea, tinea flava
Eruption of macules/patches on the skin, can be many colors .. tan, salmon, hypopigmented patches or macules
Usually on trunk
Diaper candidiasis
Presents in infant with red erosions in diaper area, with satellite lesions, involving skin folds
Pathogenesis: urease in feces breaks down urea from urine into ammonia → irritates skin → candida from feces enters the skin
Candidal intertrigo
Chicken pox
AKA varicella
Herpes zoster
AKA shingles
Herpes simplex
Kaposi sarcoma
Verruca vulgaris
AKA common wart
Genital warts
Sexually transmitted disease caused by HPV
→ verrucous sessile exophytic papules on external genitalia, perineum, perianal, inguinal fold
Extensive infection in immunocompromised (HIV, organ transplant)
HPV types 6 and 11 typically cause genital warts (recall 16 and 18 cause high grade intraepithelial neoplasia
Prevent with gardasil vaccine, protect against types 6, 11, 16, 18
Treatment: cryotherapy, electrocautery, laser, surgery, imiquimod (TLR7/8 agonist to stimulate immune system
Molluscum contagiosum
Pediculosis
AKA pediculosis capitis, lice
Lice infestation of the human head
Caused by human louse Pediculus humanus var capitis
Causes scalp pruritis (itchiness), might cause posterior cervical lymphadenopathy
Scabies
AKA seven-year itch
Contagious skin infestation by the mite Sarcoptes scabiei
Bed bugs
Human parasite that feeds on human blood found in bedding and sleep areas, active at night
Most common bed bug is Cimex lectularius
Saliva has antiplatelet agents, anticoagulant, vasodilators
Host presents with edematous papules scattered over the body
Treatment: bites resolve in a week or two; topical anti-itch or steroids for symptoms. Clean everything, hire exterminator.
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