Skin Disorders
SKIN DISORDERS
SKIN INFECTIONS
Causes:
Skin infections may be caused by:
Bacteria
Viruses
Fungi
Other types of microbes
Parasites
Caused by opportunistic microbes
Can occur through minor abrasions or cuts
Serious infections may develop
Identifying causal organism is crucial for appropriate treatment
RESIDENT FLORA
Species: Approximately 1000 species are present as resident flora
Examples include:
Staphylococcus epidermidis
Corynebacterium
Functions:
Microbial antagonism: Competes with pathogens
Competition for nutrients: Inhibits growth of harmful microbes
Can cause infections in:
Sterile body cavities
The eyes
Non-intact skin
Primary infections: Caused chiefly by staphylococci or streptococci (excluding Group A β-hemolytic strep)
Secondary infections: Develop in wounds or pruritic lesions (including scabies, psoriasis, poison ivy, atopic dermatitis)
Risk Factors: Varies by individual health status
Prevention: Regular use of soap and water
BACTERIAL INFECTIONS
CELLULITIS (ERYSIPELAS)
Definition: Infection affecting the dermis and subcutaneous tissue
Common Cause:
UsuallyStaphylococcus aureus
Sometimes Streptococcus
Typical Areas Affected:
Lower trunks and legs
Population at Risk:
Individuals with restricted circulation to extremities
Immunocompromised individuals
Symptoms:
Area becomes red, swollen, and painful
Red streaks may develop along lymphatic vessels proximal to infection
SIGNS AND SYMPTOMS OF CELLULITIS
Reddened area
Edematous (swollen)
Pain
Red streaks along lymph vessels proximal to the infected area
FURUNCLES (BOILS)
Common Cause:
Usually caused by S. aureus
Origin: Begins at hair follicles
Common Locations:
Face, neck, and back
Key Feature: Frequently drains large amounts of purulent exudate
Auto-inoculation Risk:
Squeezing can spread infection to other skin areas
SIGNS AND SYMPTOMS OF FURUNCLES
Firm, red lesion
Painful nodule that may develop into a large abscess
Abscess produces significant amounts of purulent exudate (pus)
Carbuncles: A collection of furuncles that coalesce, forming a large infected mass
TREATMENT OF FURUNCLES
Compresses: Promote drainage
Analgesics: Provide pain relief from inflammation
Surgical Intervention:
Cut and drain abscess
Antibiotic therapy to prevent further infection
IMPETIGO
Population: Common in infants and children, can also affect adults
Causative Agent:
Primarily S. aureus, highly contagious in neonates
Affected Area: Lesions mostly on the face
Transmission:
Close physical contact or contact with fomites
Common Symptom: Pruritus leads to scratching, further spreading the infection
SIGNS AND SYMPTOMS OF IMPETIGO
Small red vesicles that rapidly enlarge
Vesicles rupture, forming yellowish-brown crusty masses
Additional vesicles may develop around the primary site through autoinoculation via hands, towels, or clothes
TREATMENT OF IMPETIGO
Topical antibiotics if detected in early stages
Concerns: Increasing numbers of antibiotic-resistant strains of S. aureus may lead to local outbreaks
Systemic antibiotics if lesions are extensive
ACUTE NECROTIZING FASCIITIS
Causative Agents: Mix of aerobic and anaerobic bacteria, typically at the infection site
Common Cause: Severe inflammation and tissue necrosis often initiated by virulent strains of group A beta-hemolytic Streptococcus
Pathophysiology: Bacteria secrete toxins breaking down fascia and connective tissue leading to massive tissue destruction
History: Often initiated by minor trauma or preceding skin infection
SIGNS AND SYMPTOMS OF NECROTIZING FASCIITIS
Infected area is markedly inflamed and very painful
Infected area rapidly increases in size
Dermal gangrene is often apparent
SYSTEMIC MANIFESTATIONS
Fever
Tachycardia
Hypotension
Mental confusion and disorientation
Possibility of organ failure
TREATMENT OF NECROTIZING FASCIITIS
Therapeutics:
Aggressive antimicrobial therapy
Fluid replacement
Excision of all infected tissue
High oxygen flow therapy, such as hyperbaric chambers
Amputation may be required
Consequences of Delayed Treatment:
Greater tissue loss
Higher mortality risk due to systemic toxicity (including fever, tachycardia, hypotension, and possible organ failure)
LEPROSY (HANSEN DISEASE)
Causative Agent: Mycobacterium leprae
Classification: Chronic disease classified into three major types
Impact: Generally affects skin, mucous membranes, and peripheral nerves, which can lead to limb loss
Pathogenic Mechanism: Largely unknown
Diagnosis: Through microscopic examination of skin biopsy
Treatment: Primarily through antibiotics
VIRAL INFECTIONS
HERPES SIMPLEX
Commonality: Most frequent cause of cold sores or fever blisters
Herpes simplex type 1 (HSV-1)
Herpes simplex type 2 (HSV-2)—causes genital herpes
Both types can cause similar effects
Latent State: Virus remains latent in sensory nerve ganglia
Primary Infection: May be asymptomatic
Recurrence Triggers: Common cold, sun exposure, stress
HERPES SIMPLEX (CONTINUED)
Transmission:
Spread by direct contact with fluid from lesions
Possible transmission prior to appearance of lesions
Complications: Virus can spread to the eye causing keratitis or to fingers (herpetic whitlow)
HERPES SIMPLEX PATHWAY
Virus enters human cell.
Virus replicates inside the human cell and spreads to adjacent cells.
Viral replication causes necrosis and vesicle formation.
Immune defense controls the infection; virus migrates along the trigeminal nerve to sensory ganglion and remains in a latent state.
Recurrence triggers activation of HSV, which migrates back along the nerve to the mucocutaneous site, replicates, and a new lesion develops.
VERRUCAE (WARTS)
Causative Agent: Human papillomavirus (HPV) types 1 to 4
Population: Frequently develop in children and young adults
Common Types:
Plantar warts are common
Genital warts (HPV types 6 and 11)
Transmission: Spreads by viral shedding from the skin surface
May resolve spontaneously over time
FUNGAL INFECTIONS (MYCOSES)
Classification: Most are superficial
Systemic Spread: Candida infections can be associated with diabetes and can spread systemically in immunocompromised individuals
Diagnosis Methods:
Skin scrapings
Fluorescence under ultraviolet light
Microscopic examination
Culturing of samples
TINEA INFECTIONS
Tinea capitis:
Location: Infection of the scalp
Common in: School-age children
Appearance: Erythema may be present
Treatment: Oral antifungal medication
Tinea corporis:
Location: Infection of body on non-hairy parts
Appearance: Round lesion with a clear center (ringworm)
Symptoms: May include pruritus
Treatment: Topical antifungal medication
Tinea pedis (Athlete’s foot):
Location: Involves the feet, particularly the toes
Associated with: Swimming pools and gymnasiums
Risk: May be part of normal flora that turns opportunistic
Possible Complication: Secondary bacterial infection may occur
Treatment: Topical antifungal medication
Tinea unguium:
Location: Infection of the nails, particularly toenails
Symptoms: Nails turn white then brown, thicken, and crack; infection tends to spread to other nails
OTHER INFECTIONS
Scabies:
Caused by invasion of the mite Sarcoptes scabiei
Life Cycle:
Female burrows into epidermis, lays eggs for several weeks
Male dies after fertilization; female dies after laying eggs
Larvae migrate to the skin surface
Symptoms: Intensively pruritic; larvae create tiny light brown burrows in skin
Pediculosis (lice):
Types:
Pediculus humanus corporis (body louse)
Pediculus humanus capitis (head louse)
Pediculus humanus pubis (pubic louse)
Life Cycle:
Female lice lay eggs on hair shafts
After hatching, lice bite host and suck blood, leading to excoriations from scratching
SKIN TUMORS
KERATOSES
Definition: Benign lesions usually linked to aging or skin damage
Types:
Seborrheic keratoses:
Proliferation of basal cells leading to oval elevation
May be smooth or rough in texture
Actinic keratoses:
Develop on skin exposed to ultraviolet radiation
Common in fair-skinned individuals
Appears as pigmented, scaly patches
WARNING SIGNS OF SKIN CANCER
A sore that does not heal
Changes in the shape, size, color, or texture of a lesion, particularly if expanding with an irregular circumference
New moles or oddly shaped lesions developing
A skin lesion that repeatedly bleeds, oozes fluid, or itches
GUIDELINES TO REDUCE RISK OF SKIN CANCERS
Reduce sun exposure, especially midday and early afternoon
Cover skin with clothing
Stay in the shade
Wear broad-brimmed hats for face and neck protection
Use sunscreen or sunblock
Protect infants and children from exposure and skin damage
SQUAMOUS CELL CARCINOMA
Definition: Painless, malignant tumor of the epidermis
Common Locations: Typically on sun-exposed areas of skin and may also occur in the oral cavity
Common sites include face, neck, and base of tongue
Prognosis: Excellent prognosis with timely removal of the lesion;
Invasive forms arise from premalignant conditions
MALIGNANT MELANOMA
Definition: Highly metastatic form of skin cancer
Origins: Develops in melanocytes, often from a nevus (mole)
Characteristics:
Often appears as a multicolored lesion with an irregular border
Rapid growth and changes in shape, color, size, and texture
May bleed
Treatment Options: Surgical removal followed by radiation and chemotherapy
ABCD OF MELANOMA
A: Change in appearance
B: Change in border
C: Change in color
D: Increase in diameter
KAPOSI SARCOMA
Association: Occurs in individuals with AIDS and other immunodeficiencies
Impact: May affect both viscera and skin
Cell Origin: Malignant cells arise from endothelium in small blood vessels
Symptoms:
Appears as purplish macules
Nonpruritic and nonpainful
Key Distinction: Lesions develop rapidly over the upper body in immunocompromised patients
Treatment Options: Combination of radiation, chemotherapy, surgery, and biological therapy