Skin Notes

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Mixed flora
components differ in various areas of the body
Where microbes reside in mixed flora
under fingernails, in hair follicles, and in glands
How infections may spread from skin lesion
systematically
Location from lesions results from
length of time lesion has been present; changes occur over time
Physical appearance of lesions
color, elevation, texture, types of exudate, pain or itching
Pruritus
itching
Diagnostic tests for skin lesions
culture and staining of specimen; biopsy; blood test
Culture and staining of specimens
bacterial infections: microscopic and direct observations; specific procedures for fungal or parasitic infections
Biopsy
detection of malignant changes; safeguard prior to or following removal of skin lesion
Blood tests
helpful in diagnosis of conditions caused by allergy or abnormal immune reaction
Skin testing
uses patch or scratch method
General Treatment Measures: Pruritus
topical agents to reduce sensation; may be antihistamine or gluccocorticoids
Treatment: Avoidance of allergens
reduce risk of recurrence
Treatment: Infections
may require antibiotic treatment
Treatment: Precancerous lesions
surgery, laser therapy, electrodessication
Treatment: Cryosurgery
freezing section
Contact Dermatitis
Inflammatory disorder
Etiology/Patho of Contact Dermatitis
exposure to an allergen- type IV cell-mediated hypersensitivity reaction
Common causes of contact Dermatitis
cosmetics, plants; sensation occurs on first exposure; does not involve immune response
Direct chemical or mechanical irritation- called "irritant contact dermatitis"
accounts for 80% of cases
Signs and symptoms of Contact Dermatitis
ICD is more painful than pruritic, range form mild erythema to hemorrhage, crusting, pustules
Diagnosis of Contact Dermatitis
clinical evaluation
Treatment of Contact Dermatitis
avoid offending agents, corticosteriods
Urticaria
Inflammatory disease; "Hives"
Etiology/Patho of Urticaria
result of type I hypersensitivity; ingestion of substances; lesions are highly pruritic
Examples of ingestion causing Urticaria
shellfish, drugs, certain fruits
Hives
part of anaphylactic shock; check for swelling around mouth and check airway; EpiPen
Signs and symptoms of Urticaria
migratory, well-circumscribed, erythematous, pruritic plaques on the skin
Migratory
spread form central location
Diagnosis of Urticaria
clinical evaluation
Treatment of Urticaria
remove identified causes, symptomatic treatment(cool bath, loose clothing), antihistamines taken on regular basis
Atopic Dermatitis- Eczema
inflammatory disease; Atopic(inherited tendency)
Etiology/Patho of Atopic Dermatitis
type I hypersensitivity reaction
Signs and Symptoms of Atopic Dermatitis in INFANTS
rash is erythematous, with serous exudate; commonly on face, chest and shoulders
Signs and Symptoms of Atopic Dermatitis in ADULTS
rash is dry, scaly and pruritic, often on flexor surfaces; eosinophilia and increased serum IgE levels
Potential complications of atopic dermatitis
secondary infections
Diagnosis of atopic dermatitis
clinical evaluation
Treatment of atopic dermatitis
topical glucocorticoids, antihistamines, more common in developed countries because smaller families, cleaner indoors
Psoriasis
inflammatory disease
Etiology of Psoriasis
results form abnormal T cell activation; excessive proliferation of keratinocytes
Signs and symptoms of Psoriasis
discrete, erythematous papules or plaques covered with thick, silvery, shiny scales
Diagnosis of Psoriasis
clinical evaluation
Treatment of Psoriasis
Glucocoritcoids, coal tar preparations, antimetabolites
Pemphigus
inflammatory disease
Etiology of Pemphigus
autoimmune disease
Pathophysiology of Pemphigus
autoantibodies disrupt cohesion between epidermal cells
Signs and symptoms of Pemphigus
causes blisters, skin sheds, leaving area painful and open to secondary infection, typically occur in first month, may be life-threatening
Diagnosis of Pemphigus
clinical evaluation, sometimes biopsy
Treatment of Pemphigus
systemic glucocoritcoids and immunosuppressants
Cellulitis
Bacterial skin infection
Etiology of cellulitis
infection from dermis and subcutaneous tissue; usually staphylococcus aureus (MRSA); sometimes streptococcus
Signs and Symptoms of cellulitis
in lower trunks and legs; especially in people with restricted circulation in extremities; in immunocompromised individuals; areas become red, swollen painful, warm to touch, red streaks develop
Diagnosis of cellulitis
clinical exam
Treatment of cellulitis
antibiotics
Furuncles (boils)
skin abscess; bacterial infection
Etiology of boils
usually caused by S. aureus; begins at hair follicles; face, neck, back; frequently drains large amounts of purulent exudate
Carbuncles
collection of furuncles that coalesce to form a large infected mass
Impetigo
bacterial infection
Etiology of impetigo
S. aureus
Signs and symptoms of impetigo
superficial skin infection with honey-colored crusting or bullae; highly contagious in neonates; lesions on face
Transmission of impetigo
through close physical contact or through fomites; leads to scratching and further spread of infection
Diagnosis of impetigo
by examination
Treatment of impetigo
topical antibiotics in early stages
Necrotizing Subcutaneous Infection
acute necrotizing fasciitis
Etiology of Necrotizing
caused by "flush eating bacteria"; mixture of aerobic and anaerobic bacteria; caused by virulent strain of gram-positive, group A beta-hemolytic strep; bacteria secrete toxins that break down fascia and connective tissue, widespread occlusion of subcutaneous vessels
Signs and symptoms of necrotizing
acutely ill, tachycarida, high fever, intense pain, affected tissue becomes rapidly discolored, muscles are spared initially
Diagnosis of necrotizing
clinical exam, blood and wound cultures
Treatment of necrotizing
surgical debridement, antibiotics, amputation
Leprosy
cases in U.S. involve people who emigrated from developing countries; unclear spreading; people with this probably have genetic predisposition
Etiology of Leprosy
chronic infection from mycobacterium leprae
Signs and Symptoms of Leprosy
usually don't begin until after year of infection, skin macules, papules, nodules, peripheral numbness, destruction of nasal septum
Diagnosis of Leprosy
microscopic examination of skin biopsy
Treatment of leprosy
primarily with antibiotics
Scabies
parasitic infection
Etiology of Scabies
invasion by mite sarcoptes scabie; easily transmitted through physical contact
Pathogenesis of Scabies
female burrows into epidermis, lays eggs, male dies after fertilizing female, female dies after laying eggs, burrow into skin in search of nutrients
Signs and symptoms of Scabies
erythematous papules appear in finger web spaces, itchy, burrows appear on skin as tiny, light brown or grey lines
Diagnosis of scabies
clinical evaluation, burrow scrapings
Treatment of scabies
topical scabicides
Pediculosis
lice
Etiology of pediculosis
infestation from pedicures humans capitis- head louse; female lays eggs on hair shaft, after hatching louse bites human host, sucking blood for protection of ova, exoriations result from scratching
Skin Tumors- Squamous Cell Carcinoma
malignant tumor of epidermal keratinocytes that invades the dermis; 2nd most common
signs and symptoms of carcinoma
may begin as red papule or plaque; may have scaly or crusted surface; may become nodular
diagnosis of head lice
demonstration
treatment of head lice
oral invermectin, topical pedicuoide hair treatments
Diagnosis of carcinoma& melanoma
biopsy essential
Malignant melanoma
malignant tumors of melanocytes; occur mainly on skin but also on mucosa; 40-50% develop from moles
ABCD of Melanoma- A
change in appearance
B
Change in border
C
change in color
D
increase in diameter
treatment of melanoma
curettage, electrodissection, cryosurery, topical chemotherapy