SKIN DISORDERS Flashcards
Layers of the skin
- Epidermis—avascular
- Dermis
- Subcutaneous tissue (hypodermis)
Epidermis
Five layers—vary in thickness
Keratin: Waterproofing of the skin
Melanin: Skin pigment—determines skin color
• Production depends on multiple genes and environment
Albinism : Lack of melatonin production
Vitiligo: Small areas of hypopigmentation
Melasma: Patches of darker skin
Dermis
Connective tissue
- Contains elastic and collagen fibers
-Flexibility and strength of the skin
-Contains nerves and blood vessels: Includes sensory receptors for: Pressure Touch Pain Heat Cold
Appendages of the Skin
Hair follicles
-Stratum basale—hair-producing
• Arrector pili muscle associated with hair follicle
Sebaceous glands
-Produce sebum
• Secretion increases at puberty—influence of sex hormones
Sweat glands
-Eccrine—all over body
-Apocrine
• Axillae, scalp, face, external genitalia
Skin lesions may be caused by:
Systemic disorders • Liver disease Systemic infections • Chickenpox Allergies to ingested food or drugs Localized factors • Include exposure to toxins
Types of lesions
Location Length of time lesion has been present Changes occurring over time Physical appearance • Color • Elevation • Texture • Type of exudate Presence of pain or pruritus (itching)
Pruritus
Release of histamine in a hypersensitivity response causes marked pruritus
Diagnostic Tests for Skin Lesions
Culture and staining of specimens:Bacterial infections: microscopic and direct observations AND Specific procedures for fungal or parasitic infections
Biopsy: Detection of malignant changes
• Safeguard prior to or following removal of skin lesions
Blood tests: Helpful in diagnosis of conditions caused by allergy or abnormal immune reaction
Skin testing using patch or scratch method
General Treatment Measures
General Treatment Measures Pruritus -Topical agents to reduce sensation -May be treated by antihistamines or glucocorticoids Avoidance of allergens -Reduce risk of recurrence Infections -May require antibiotic treatment Precancerous lesions -Surgery, laser therapy, electrodessication, cryosurgery
Contact Dermatitis
Pruritic rash develops at site a few hours after exposure.
Urticaria (Hives)
Result of type I hypersensitivity
-Ingestion of substances
• Examples: shellfish, drugs, certain fruits
Lesions are highly pruritic.
Hives are often part of anaphylaxis!
-Check for swelling around mouth and check airway.
-Administer EpiPen or other first aid as required.
Atopic Dermatitis (Eczema)
Atopic—inherited tendency
Common problem in infancy
-Rash is erythematous, with serous exudate.
-Commonly occurs on face, chest, and shoulders
In adults, rash is dry, scaly, and pruritic, often on flexor surfaces.
Chronic inflammation results from response to allergens.
-Eosinophilia and increased serum IgE levels
Potential complication—secondary infections
Treatment
-Topical glucocorticoids, antihistamines
Psoriasis
Chronic inflammatory skin disorder
Onset usually in the teenage years
Psoriasis results from abnormal T cell activation.
–Excessive proliferation of keratinocytes
–Cellular proliferation is greatly increased.
Lesions found on face, scalp, elbows, knees
–Itching or burning sensations
Treatment
–Glucocorticoids, tar preparations, antimetabolites
Pemphigus
Autoimmune disorder
Autoantibodies disrupt cohesion between epidermal cells.
-Causes blisters (bullae) to form
-Skin sheds, leaving area painful and open to secondary infection.
-May be life-threatening if extensive (e.g., Stevens-Johnson syndrome)
Systemic glucocorticoids and immunosuppressants
Scleroderma
May occur as skin disorder
May be systemic and affect viscera
Primary cause unknown
-Increased collagen deposition is observed in all cases.
-Inflammation and fibrosis with decreased capillary networks
• Hard, shiny, tight, immovable areas of skin
• Impaired movement of mouth and eyes
May cause renal failure, intestinal obstruction, respiratory failure caused by distortion of tissues
Skin Infections
May be caused by bacteria, viruses, fungi, other types of microbes, parasites
Caused by opportunistic microbes
Minor abrasions or cuts
Serious infections may develop.
Causative organism needs to be identified for appropriate treatment
Cellulitis (erysipelas)
bacterial infections
Infection of the dermis and subcutaneous tissue
Usually secondary to an injury
May be iatrogenic
Causative organism
• Usually Staphylococcus aureus
• Sometimes Streptococcus
Frequently in lower trunks and legs
• Especially in individuals with restricted circulation in the extremities; also in immunocompromised individuals
• Area becomes red, swollen, and painful
• Red streaks may develop, running along lymph vessels proximal to infected area
Furuncles (boils)
Usually caused by S. aureus
• Begins at hair follicles
• Face, neck, back
• Frequently drains large amounts of purulent exudate
Autoinoculation
• Squeezing boils can result in spread of infection to other areas of the skin.
Carbuncles
• Collection of furuncles that coalesce to form a large infected mass
Impetigo
Common infection in infants and children
-May also occur in adults
-S. aureus—highly contagious in neonates
Lesions commonly on face
Transmission may occur through close physical contact or through fomites
Pruritus common
-Leads to scratching and further spread of infection
Impetigo: Treatment
Topical antibiotics in early stages
Systemic administration if lesions are extensive
-Antibiotic-resistant strains of S. aureus are increasing in numbers.
• Local outbreaks of infection may result.
Acute Necrotizing Fasciitis
Mixture of aerobic and anaerobic bacteria usually at site of infection
Severe inflammation and tissue necrosis
-Usually caused by virulent strain of gram-positive, group A beta-hemolytic Streptococcus
-Bacteria secrete toxins that break down fascia and connective tissue, causing massive tissue destruction.
Often a history of minor trauma or infection in the skin and subcutaneous tissue of an extremity
Delay in treatment—greater tissue loss, potential amputation, higher probability of mortality
Systemic toxicity develops with fever, tachycardia, hypotension, mental confusion, disorientation, possible organ failure
Treatment
-Aggressive antimicrobial therapy, fluid replacement
-Excision of all infected tissue; amputation
Leprosy (Hansen’s Disease)
Caused by Mycobacterium leprae
Chronic disease classified into three major types
Clinical signs and symptoms vary.
-Generally affects skin, mucous membranes, and peripheral nerves
-Damage can lead to loss of limbs.
Mechanism of pathogenicity largely unknown
Diagnosis through microscopic examination of skin biopsy
Treatment primarily with antibiotics
Herpes Simplex
Herpes simplex type 1 (HSV-1)
-Most common cause of cold sores or fever blisters
Herpes simplex type 2 (HSV-2)—genital herpes
Both types of HSV cause similar effects.
Primary infection may be asymptomatic
-Virus remains latent in sensory nerve ganglia.
Recurrence may be triggered by:
-Common cold, sun exposure, stress
Herpes Simplex (Cont.) SPREAD
Spread by direct contact with fluid from lesion
Spread of infection to others possible prior to appearance of lesions
Potential complication
-Spread of virus to eye
• Keratitis
-Herpetic whitlow
• Painful infection of the fingers
