Dermatology Flashcards
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What is contact dermatitis?
- Inflammatory skin reaction resulting from contact with an external agent
- Rhus dermatitis is an allergic dermatitis caused by contact with poison ivy or oak
What are the signs of contact dermatitis?
- Patients complain of itching and burning in the effected area
- Sharply demarcated, erythematous vesicles and plaques at site of contact with agent
- Chronic lesions may be linchenified
- Satellite papules and excoriations are common
How do we diagnose contact dermatitis?
- Clinical: consider location, relationship to external factors, particular configurations
- Patch tests that result in similar reactions support the diagnosis
How do we treat contact dermatits?
- Remove offending agent
- Topical lubrication
- Wet dressings soaked in Burrow’s solution (aluminum acetate in water)
- Topical corticosteroids for chronic lesions
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Atopic dermatitis
What is atopic dermatitis?
- Eczema is a broad term used to describe several inflammatory skin reactions; used synonymously with dermatitis.
- By definition atopic dermatitis is a hypersensitivity response.
Etiology:
- Type 1 (IgE) immediate hypersensitivity response
- Atopic dermatitis is part of the atopic triad: allergic rhinitis, asthma, and eczema
What are the signs and symptoms of atopic dermatitis?
- Patients complain of dry, pruritus, scaly skin. Scratching leads to lichenification
- Pruritic, you can think of atopic dermatitis as “the itch that rashes”
- Susceptible to secondary bacterial (S. aureus) and viral (herpes simplex virus) infections
How do we diagnose atopic dermatitis?
- Clinical; supported by personal or family history of atopy
- Don’t’ culture skin in atopic dermatitis – 90% of atopic patients are carriers for S. aureus
How do we treat atopic dermatitis?
- Topical corticosteroids are the mainstay of therapy
- Oral antihistamines to help reduce itching
- Lubricate dry skin
- Oral antibiotics only if clinical signs of secondary infection
How does the presentation of atopic dermatitis change amongst the pediatric population?
Lesions vary with patient age:
- Infantile- red, exudative, crusty, and oozing lesions primarily affecting face (especially cheeks) and extensor surfaces. Nose and paranasal areas often spared, the diaper area is also spared
- Juvenile/adult: dry, lichenified, pruritic plaques distributed over flexural areas (antecubital, popliteal, neck)
What is diaper dermatitis?
- Irritant contact dermatitis: Prolonged dampness, interaction of urine (ammonia) and feces with the skin, reactions to medications/creams, type of diaper
- Candida or bacterial secondary infection can occur with satellite lesions
Pathophysiology:
- Overhydrating, friction, maceration, allergy, etc.
What are the signs and symptoms of diaper dermatitis?
- Red, scaly, fissured, eroded skin within the boarders of the diaper
- Patchy or confluent
What is the treatment for diaper dermatitis?
- Keep infant dry, change diapers often
- Avoid harsh detergents, wipes with alcohol, and plastic pants
- Ointment can reduce friction and protect skin from irritation
What is periorbital dermatitis?
- Typically occurs in young women; often with a history or prior topical steroid use in the area exists
What are the signs and symptoms of periorbital dermatitis?
- Papulopustules form on erythematous bases and may become confluent with plaques and scales, vermillion boarder is spared and satellite lesions are common
How do we treat periorbital dermatitis?
- Use topical metronidazole or erythromycin or oral minocycline, doxycycline, or tetracycline
- Untreated lesions will fluctuate over time, similar to rosacea
What are drug eruptions?
- Abnormal immunologically mediated hypersensitivity responses
- Relatively rare
What are the signs and symptoms of a drug eruption?
- Mild rash to anaphylaxis
- Fixed drug eruptions: recur at the same site after each administration of causative drug (sulfonamides are the most common)
- Most are afebrile. May worsen before improving after discontinuation of the drug
How do we diagnose a drug eruption?
- Eosinophilia is a clue but is not diagnostic
- Skin test is available for penicillin. It is not indicated for the patients with a history of penicillin-associated anaphylaxis, urticarial, or serum sickness
What is the treatment for a drug eruption?
- Discontinue likely offending agent
What are the most common causes of drug eruptions?
- Potentially any drug can cause a drug reaction
- Most common causes of drug reactions: penicillin, sulfonamide
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Drug eruption
What is lichen planus?
- This is an acute or chronic inflammatory dermatitis that occurs in adults.
What causes lichen planus?
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What are the signs and symptoms of lichen planus?
- Designated as the 4 P’s: purple, polygonal, pruritic and papule
- Lesions are flat topped, shiny, violaceous papules with fine white lines on the surface (Wickham striae). They typically are grouped and most commonly occur on the flexor aspect of the wrists, lumbar area, eyelids, shins, and scalp. Koebner phenomenon is seen.
- Lesions may affect hair (scarring alopecia) or nails (destruction of nail fold and nail bed with longitudinal splintering
How do we diagnose lichen planus?
- Biopsy and immunofluorescence confirm diagnosis
What is the treatment for lichen planus?
- Topical steroids with occlusive dressings are used
- Intralesional steroids or topical tretinoin is used for severe localized lesions
- Cyclosporine mouthwash is used for oral lesions
- Systemic therapy (cyclosporine, corticosteroids, or retinoids) may be needed in severe, painful cases
What is pityriasis rosea?
- Common, self-limited eruption of single herald patch followed by a generalized secondary widespread symmetrical papular eruption
What causes pityriasis rosea?
- Unknown but us thought to be viral
What are the signs and symptoms of pityriasis rosea?
- There may be a mild upper respiratory tract infection-like prodrome before onset of rash
- Herald plaque- 2 to 10 cm solitary, oval, erythematous, with collarette of scale. It typically precedes rash by a week or so
- After a few days to a few weeks, followed in 80% by generalized eruption of multiple smaller, pink, oval, scaly patches over trunk and upper extremities in a “Christmas tree” distribution (oriented parallel to ribs).
- Pruritus
How is pityriasis rosea diagnosed?
- Clinical
- Rapid plasma reagin (RPR) to differentiate from syphilis if suspected, KOH to differentiate from fungal infection.
- The herald patch may be mistaken for tinea corpis
What is the treatment for pityriasis rosea?
- Self-limited, resolves in 3-8 weeks
- Symptomatic: the goal is to control pruritus (baths, calamine, topical corticosteroids, oral antihistamines)
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pityriasis rosea
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Steven-Johnson Syndrome
What is steven-johnson syndrome?
- Extreme variant of erythema multiforme (EM) with systemic toxicity and involvement of the mucous membranes.
What causes steven johnson syndrome?
- Often viruses (herpes) or drugs
- Drugs: sulfonamides and anticonvulsants
- Mycoplasma pneumonia, herpes simplex virus
What are the signs and symptoms of steven-johnson syndrome?
- Prodromal phase (1-14 days): fever, headache, malaise
- Severe mucous membranes involvement (oral, vaginal conjunctival). Oral erosions on the palate and gingivae.
- Extensive target like lesions and mucosal erosions covering < 10% of body surface area. Annular, with pink halo surrounding a pale halo and erythematous center. Palms and soles are involved.
- Nikolsky sign: separation of normal epidermis at the basal layer caused by sliding finger pressure (“rubbed off” line)
- Ocular involvement (purulent uveitis/exudative conjunctivitis) may result in scaring or corneal ulcers
How is steven-johnson syndrome diagnosed?
- Clinical criteria: cutaneous lesion plus at least two mucosal surfaces involved
- Skin biopsy is diagnostic (would show perivascular mononuclear cell infiltrate)
How is steven-johnson syndrome treated?
- Hospitalization for supportive care, IV hydration
- Discontinue offending agent (if identified)
- Mouthwashes, topical steroids and anesthetics, pain control as needed
- Regrowth of skin for SJS and TEN takes 3 weeks and is delayed in pinpoint areas
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Toxic Epidermal Necrosis
What is Toxic Epidermal Necrosis?
- Increased severe variant/progression of erythema multiforme with widespread involvement.
- Widespread blister formation and morbilliform or confluent erythema with skin tenderness
- Sudden onset and generalization within 24-48 hours
- Can be life threatening
What are the signs and symptoms of Toxic Epidermal Necrosis?
- TEN exhibits a higher fever and more severe epidermal separation and loss compared with SJS
- Widespread, full-thickness necrosis of skin, covering > 30% body surface area
- Abrupt onset of fever and influenza like symptoms
- Pruritus, pain, tenderness and burning
- Absence of target lesions
How do we diagnose Toxic Epidermal Necrosis?
- Clinical; confirm biopsy
How is Toxic Epidermal Necrosis treated?
- Removal and/or treatment of causative agent
- Hospitalization for severe disease
- Fluid and electrolyte replacement
- Systemic corticosteroids
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Erythema Multiforme