Dermatology Flashcards
What is pruritus?
A sensation provoking a desire to scratch, with or without skin lesions
What are the categories of etiology for pruritus?
- Dermatologic - generalized
- Dermatologic - local
- Systemic disease – usually generalized
What systemic diseases can cause pruritus?
- Hepatic: obstructive biliary disease, cholestatic liver disease of pregnancy
- Renal: chronic renal failure, uremia secondary to hemodialysis
- Hematologic: Hodgkin’s lymphoma, multiple myeloma, leukemia, polycythemia vera, hemochromatosis, Fe deficiency anemia, cutaneous T-cell lymphoma
- Neoplastic: lung, breast, gastric (internal solid tumours), non-Hodgkin’s lymphoma
- Endocrine: carcinoid, DM, hypothyroid/thyrotoxicosis
- Infectious: HIV, trichinosis, echinococcosis, hepatitis C
- Psychiatric: depression, psychosis
- Neurologic: post-herpetic neuralgia, multiple sclerosis
What local dermatologic diseases can cause pruritus?
- Atopic and contact dermatitis, lichen planus, urticaria, insect bites, dermatitis herpetiformis
- Infection: varicella, candidiasis
- Lichen simplex chronicus
- Prurigo nodularis
What generalized dermatologic diseases can cause pruritus?
- Asteatotic dermatitis (“winter itch” due to dry skin)
- Pruritus of senescent skin (may not have dry skin, any time of year)
- Infestations: scabies, lice
- Drug eruptions: ASA, antidepressants, opiates
- psychogenic states
What should be asked on history for pruritus?
- New cosmetics or creams - Allergic contact dermatitis, urticaria, photodermatitis
- New medications, supplements, or illicit drugs - Urticaria, fixed drug eruptions
- Recent travel - Pediculosis, scabies infestation, photodermatitis, urticaria
- Hobby or occupational exposure to solvents, adhesives, cleaners - Irritant contact dermatitis, xerosis, atopic dermatitis, eczema
- New animal exposures - Flea infestation, allergic contact dermatitis, urticaria
- Sick contacts, especially those with febrile diseases and rashes - Rubeola, mumps, varicella, scarlet fever, cellulitis, fifth disease, folliculitis
- Unexplained weight changes, menstrual irregularity, heat/cold intolerance - Thyroid disease with secondary urticaria or xerosis
- Unexplained weight loss, night sweats, unexplained fevers, fatigue - Lymphoma with secondary generalized pruritus
- Malaise, nausea, decreased urine output - Renal failure with generalized pruritus
What should be done on physical exam for pruritus?
- An evaluation of the liver, spleen, and lymph nodes.
- Organomegaly increases the likelihood of an underlying systemic disease, such as lymphoma.
- The skin should also be examined. Finger webs, intertriginous regions, and the genitals should be evaluated for the presence of scabies or lice.
Investigations for pruritus?
CBC, TSH, fasting glucose, ALP, bili, Cr, BUN, LFT, stool culture
General management for pruritus?
- Treat underlying cause
- Cool water compresses to relieve pruritus
- Bath oil and emollient ointment (especially if xerosis is present)
- Topical corticosteroid and antipruritics (e.g. menthol, camphor, phenol, mirtazapine, capsaicin)
- Systemic antihistamines: H1 blockers are most effective, most useful for urticaria
- Phototherapy with UVB or PUVA
- Doxepin, amitriptyline
- Immunosuppressive agents if severe: steroids and steroid-sparing
How do you describe skin lesions?
- Size
- Colour
- Arrangement
- Lesion Morphology
- Distribution
- ALWAYS remember scalp, hair, nails, mucous membranes, feet
Type I acne
Type I: comedonal, sparse, no scarring
Type II acne
Type II: comedonal, papular, moderate ± little scarring
Type III acne
Type III: comedonal, papular, and pustular, with scarring
Type IV acne
Type IV: nodulocystic acne, risk of severe scarring
Pathophysiology of acne
- Hyperkeratinization at the follicular ostia (opening) blocks the secretion of sebum leading to the formation of microcomedones
- Androgens promote excess sebum production
Treatment of mild acne?
- Topical OTC therapies: benzoyl peroxide, salicylic acid
- Antimicrobials: clindamycin
- Retinoids: Vitamin A acid
Treatment of moderate acne?
- Tetracycline, minocycline
- Spironolactone
Treatment of severe acne?
Isotretinoin
What is rosacea
Chronic inflammation of skin and is especially associated with triggers that increase body temperature.
Triggers for rosacea
- Hot weather, hot drinks, spicy food
- Stress, alcohol, nicotine
- Demodex mites
Clinical features of erythematotelangiectatic rosacea
- Facial flushing
- Persistent erythema of the face (together with telangiectasias)
Clinical features of papulopustular rosacea
- Papules, pustules, and erythema
- Comedones are not present in patients with rosacea.
Clinical features of phymatous rosacea
- Skin and sebaceous glands thicken
- Inflammatory, widespread nodules
- Rhinophyma: enlarged, bulbous nose (almost exclusively in males)
- Similar changes may occur on the chin, forehead, cheeks, and ears
Clinical features of ocular rosacea
- Conjunctival hyperemia (most common)
- Blepharitis (inflammation of the eyelid margin), stye (hordeolum externum), chalazion
- Dry eyes and foreign-body sensation
- Keratitis
Treatment of rosacea
- Avoid triggers
- Medical therapy
- Laser therapy: for erythema, telangiectasias, and phymatous rosacea
- Surgical therapy: for phymatous rosacea; includes electrocautery and dermabrasion
Clinical features of atopic dermatitis?
- Subacute and chronic eczematous reaction associated with prolonged severe pruritus
- Inflammation, lichenification, excoriations are secondary to relentless scratching
- Atopic Palms: hyperlinearity of the palms
Pathophysiology of atopic dermatitis?
T-cell driven inflammatory process with epidermal barrier dysfunction
Epidemiology of atopic dermatitis?
Frequently affects infants/children/young adults; 10-20% children in developed countries under the age of 5 are affected - associated with PMHx/FHx of atopy (asthma, hay fever), anaphylaxis, eosinophilia
Distribution of atopic dermatitis?
- Infants: head + flexure surfaces (elbows)
- Children: neck + extensor surfaces (behind knees, in elbows)
- Adults: neck + hands/feet (lichenification of skin in adults)
Non-pharmacology treatment of atopic dermatitis?
- AVOID triggers: irritants, contact allergens, environmental, inappropriate bathing habits – long hot shower, sweating, microbes, stress
- Moisturizers: apply liberally and reapply at least BID with goal of minimizing xerosis; include in treatment of mild-severe disease as maintenance therapy
- Bathing Practices: bathe in plain warm water for a short period of time once daily followed by lightly but NOT completely drying the skin with a towel»_space;> immediately apply topical agents/moisturizers after this - use fragrance free hypoallergenic non-soap cleansers
Pharmacology treatment of atopic dermatitis?
- Topical Corticosteroids: effective in reducing acute/chronic sx as well as prevention of flares
- Topical Calcineurin Inhibitors (Tacrolimis, Pimecrolimus): use as steroid-sparing agents in the long-term
- Adjuncts: antihistamines + psychological interventions
Treatment of erythema, flushing, skin sensitivity, xerosis in rosacea
Topical brimonidine, Topical oxymetazoline
Treatment of mild papules and pustules in rosacea
Metronidazole (also for ocular rosacea), Azelaic acid, Ivermectin, Sodium sulfacetamide
Treatment of moderate to severe papules and pustules in rosacea
Tetracyclines: e.g., doxycycline (also for ocular rosacea), tetracycline, minocycline, Isotretinoin (first-line for phymatous rosacea)
Refractory treatment of atopic dermatitis?
Azathioprine + MTX + PO cyclosporine + PO steroids + phototherapy + potent topical steroids + psychotherapeutics
Two types of contact dermatitis?
- Irritant Dermatitis
- Allergic Contact Dermatitis
Mechanism of reaction for irritant dermatitis?
Toxic injury to skin; non-immune mechanism
Clinical features of irritant dermatitis?
- Erythema, dryness, fine scale, burning
- Acute: quick reaction, sharp margins (e.g. from acid/alkali exposure)
- Cumulative insult: slow to appear, poorly defined margins (e.g. from soap), more common
Management of irritant dermatitis?
- Avoidance of irritants
- Wet compresses with Burrow’s solution
- Barrier moisturizers
- Topical/oral steroids
Mechanism of reaction for allergic contact dermatitis?
Cell-mediated delayed (Type IV) hypersensitivity reaction
Clinical features of allergic contact dermatitis?
- Type of reaction: Erythema with a papulovesicular eruption, swelling, pruritus
- Distribution: Areas exposed to allergen
Treatment of allergic contact dermatitis?
- Patch testing to determine specific allergen
- Avoid allergen and its cross-reactants
- Wet compresses soaked in Burrow’s solution (drying agent)
- Topical steroids BID prn
- Systemic steroids prn if extensive
Clinical features of dyshidrotic dermatitis
- “tapioca pudding” papulovesicular dermatitis of hands and feet that coalesce into plaques, followed by painful fissuring
- Acute stage often very pruritic
- Lesions heal with desquamation and may lead to chronic lichenification
- Sites: palms and soles¬ ± dorsal surfaces of hands and feet
Pathophysiology of dyshidrotic dermatitis
- unknown
- NOT caused by hyperhidrosis (excessive sweating)
- Emotional stress may precipitate flares
Management of dyshidrotic dermatitis
- Topical: high potency corticosteroid with plastic cling wrap occlusion to increase penetration
- Intralesional triamcinolone injection
- Systemic
o prednisone in severe cases
o alitretinoin (Toctino) for all types of chronic hand dermatitis, including dyshidrotic dermatitis
o antibiotics for secondary S. aureus infection
Clinical features of nummular dermatitis
- Nummular (coin-shaped), pruritic, dry, scaly, erythematous plaques
- Often associated with atopic and dyshidrotic dermatitis
Management of nummular dermatitis
- Moisturization
- Mid to high potency corticosteroid ointment twice daily
Distribution of seborrheic dermatitis
- Infants: “cradle cap”
- Children: may be generalized with flexural and scalp involvement
- Adults: diffuse involvement of scalp margin with yellow to white flakes, pruritus, and underlying erythema
Clinical features of seborrheic dermatitis
Greasy, erythematous, yellow, scaling, minimally elevated papules and plaques in areas rich in sebaceous glands, can look moist and superficially eroded in flexural regions
Pathophysiology of seborrheic dermatitis
Possible etiologic association with Malassezia spp. (yeast)
Management of seborrheic dermatitis
- Face: ketoconazole cream daily or bid and/or mild steroid cream daily or bid
- Scalp: salicylic acid in olive oil or Derma-Smoothe lotion to remove dense scales, 2% ketoconazole shampoo, ciclopirox, shampoo, selenium sulfide or zinc pyrithione (e.g. Head and Shoulders) shampoo, steroid lotion (e.g. betamethasone valerate 0.1% lotion bid)
Clinical features of stasis dermatitis
- Erythematous, scaly, pruritic plaques in lower legs, particularly the medial ankle
- Brown hemosiderin deposition, woody fibrosis, atrophy blanche, and lipodermatosclerosis in late stages
- Usually bilateral, accompanied by swelling, oozing, crusting, may have accompanying varicosities
Pathophysiology of stasis dermatitis
- Chronic venous insufficiency leads to venous stasis
- Surrounding soft tissue inflammation and fibrosis results
Investigations of stasis dermatitis
- Doppler and colour-coded Duplex sonography if suspicious for DVT
- Swab for bacterial culture if there is crusting
Management of stasis dermatitis
- Compression stockings
- Rest and elevate legs (above the level of the heart)
- Moisturizer to treat xerosis
- Mid-high potency topical corticosteroids to control inflammation
Clinical features of lichen simplex chronicus
- Well-defined plaque(s) of lichenified skin with increased skin markings ± excoriations
- Common sites: neck, scalp, lower extremities, urogenital area
- Often seen in patients with atopy
Pathophysiology of lichen simplex chronicus
- Skin hyperexcitable to itch, continued rubbing/scratching of skin results
- Eventually lichenification occurs
Investigations of lichen simplex chronicus
- If patient has generalized pruritus, rule out systemic cause: CBC with differential count, transaminases, bilirubin, renal and thyroid function tests, TSH, glucose, SPEP
- CXR if lymphoma suspected
Management of lichen simplex chronicus
Antipruritics (e.g. antihistamines, topical or intralesional glucocorticoids, Unna boot)
Clinical features of lichen planus
- Morphology: pruritic, well-demarcated, violaceous, polygonal, flat-topped papules
- Characterized by the six P’s (pruritus, polygonal, planar, purple, papules, plaques)
- Koebner phenomenon
- Wickham’s striae: reticulate white-grey lines over mucosal surface; pathognomonic but may not be present
Pathophysiology of lichen planus
- autoimmune, antigen unknown
- lymphocyte activation leads to keratinocyte apoptosis
Investigations of lichen planus
- Clinical diagnosis but consider a punch biopsy
- Hepatitis C serology if patient has risk factors
Distribution of lichen planus
- Common sites: wrists, ankles, mucous membranes in 60% (mouth, vulva, glans), nails, scalp
- Distribution: symmetrical and bilateral
Management of lichen planus
- Topical or intralesional corticosteroids
- Short courses of oral prednisone (rarely)
- Phototherapy or oral retinoids or systemic immunosuppressants (e.g. azathioprine, methotrexate, cyclosporine) for extensive or recalcitrant cases
Clinical features of initial eruption of pityriasis rosea?
Initial eruption: herald patch (mother patch)
- Single ovoid macule or patch, 2-10 cm in diameter
- Slightly raised, dark red border with a central salmon-colored clearing zone
- Surrounded by a collarette: a collar of fine, white scales (like cigarette paper)
- Typically on the back
Clinical features of secondary eruption of pityriasis rosea?
- Bilateral diffuse, oval-shaped, salmon-colored papules and plaques (< 1.5 cm) with scaly collarette
- Papules appear along Langer lines, which align on the back like the branches of a Christmas tree (Christmas tree appearance)
- Typically seen on the trunk (thorax, back, abdomen), neck, and upper extremities
Etiology of pityriasis rosea?
Suspected HHV-7 or HHV-6 reactivation
Management of pityriasis rosea?
- None required; clears spontaneously in 6-12wk
- Symptomatic: topical glucocorticoids if pruritic, cool compresses, emollients
Classification of psoriasis
- plaque psoriasis
- guttate psoriasis
- erythrodermic psoriasis
- pustular psoriasis
- inverse psoriasis
Clinical features of plaque psoriasis
- Chronic and recurrent disease characterized by well-circumscribed erythematous papules/plaques with silvery-white scales
- Often worse in winter (lack of sun)
- Auspitz sign: bleeds from minute points when scale is removed
- Common sites: scalp, extensor surfaces of elbows and knees, trunk (especially buttocks), nails, pressure areas
Management of mild (<3% BSA) plaque psoriasis
- topical steroids, topical vitamin D3 analogues, or a combination of the two are first line
- topical retinoid ± topical steroid combination, anthralin, and tar are also effective but tend to be less tolerated than first line therapies
- emollients
- phototherapy or systemic treatment may be necessary if the lesions are scattered or if it involves sites that are difficult to treat such as palms, soles, scalp, genitals
Management of moderate (3-10% BSA) to severe (>10% BSA) plaque psoriasis
- goal of treatment is to attain symptom control that is adequate from patient’s perspective
- phototherapy if accessible
- systemic or biological therapy based on patient’s treatment history and comorbidities
- topical steroid ± topical vitamin D3 analogue as adjunct therapy
Clinical features of guttate psoriasis
- Discrete, scattered salmon-pink small scaling papules
- Sites: diffuse, usually on trunk and legs, sparing palms and soles
- Often antecedent streptococcal pharyngitis
Management of guttate psoriasis
- UVB phototherapy, sunlight, lubricants, topical steroids
- Penicillin V or erythromycin if Group A β-hemolytic Streptococcus on throat culture
Clinical features of erythrodermic psoriasis
- Generalized erythema (>90% of BSA) with fine desquamative scale on surface
- Associated signs and symptoms: arthralgia, pruritus, dehydration, electrolyte imbalance
- Triggered by having a Hx of psoriasis then start new drug/steroids/etc.
- Aggravating factors: lithium, β-blockers, NSAIDs, antimalarials, phototoxic reaction, infection
Management of erythrodermic psoriasis
- IV fluids, monitor fluids and electrolytes, may require hospitalization
- Treat underlying aggravating condition, suna voidance
- Cyclosporine, acitretin, methotrexate, UV, biologics
Clinical features of pustular psoriasis
- Sudden onset of erythematous macules and papules which evolve rapidly into pustules, can be painful
- May be generalized or localized
- Patient usually has a history of psoriasis; may occur with sudden withdrawal from steroid therapy
Management of pustular psoriasis
- methotrexate, cyclosporine, acitretin, UV, biologics
Clinical features of inverse psoriasis
- Erythematous plaques on flexural surfaces such as axillae, inframammary folds, gluteal fold, inguinal folds
- Lesions may be macerated
Management of inverse psoriasis
- Low potency topical corticosteroids
- Topical vitamin D derivatives (e.g. calcipotriene, calcitriol)
- Topical calcineurin inhibitors (e.g. tacrolimus, pimecrolimus)
Clinical features of bullous pemphigoid
- Chronic autoimmune bullous eruption characterized by pruritic, tense, subepidermal bullae on an erythematous or normal skin base. Affects skin, not mucous membranes. Tense bullae – may be serous or hemorrhagic. As the bullae age, they eventually become flaccid and rupture, leaving erosions and serous or hemorrhagic crusts. NEGATIVE NIKOLSKY’S SIGN.
- Can present as urticarial plaques without bullae
- Common sites: flexor aspect of forearms, axillae, medial thighs, groin, abdomen
Pathophysiology of bullous pemphigoid
- IgG produced against dermal-epidermal basement membrane proteins (hemidesmosomes) leads to subepidermal bullae
Investigations of bullous pemphigoid
- Immunofluorescence shows linear deposition of IgG and C3 along the basement membrane
- Anti-basement membrane antibody (IgG) (pemphigoid antibody detectable in serum)
Management of bullous pemphigoid
- Prednisone 0.5-1 mg/kg/d until clear, then taper ¬ ± steroid-sparing agents (e.g. azathioprine, cyclosporine, mycophenolate mofetil)
- Topical potent steroids (clobetasol) may be as effective as systemic steroids in limited disease
- Tetracycline ¬ ± nicotinamide is effective for some cases
- Immunosuppressants such as azathioprine, mycophenolate mofetil, cyclosporine
- IVIg and plasmapheresis for refractory cases
Clinical features of pemphigus vulgaris
- Autoimmune blistering disease characterized by flaccid, non-pruritic intraepidermal bullae/vesicles on an erythematous or normal skin base. Affects skin and mucous membranes
- May present with erosions and secondary bacterial infection
- Sites: mouth (90%), scalp, face, chest, axillae, groin, umbilicus
- Nikolsky’s sign: epidermal detachment with shear stress
- Asboe-Hansen sign: pressure applied to bulla causes it to extend laterally
Pathophysiology of pemphigus vulgaris
IgG against epidermal desmoglein-1 and -3 lead to loss of intercellular adhesion in the epidermis
Epidemiology of pemphigus vulgaris
Paraneoplastic pemphigus may be associated with thymoma, myasthenia gravis, malignancy, and use of D-penicillamine
Investigations of pemphigus vulgaris
- Immunofluorescence: shows IgG and C3 deposition intraepidermally
- Circulating serum anti-desmoglein IgG antibodies
Management of pemphigus vulgaris
Prednisone 1-2mg/kg until no new blisters, then 1-1.5mg/kg until clear, then taper ¬ ± steroid-sparing agents (e.g. azathioprine, cyclophosphamide, cyclosporine, IVIg, mycophenolate mofetil, rituximab)
Clinical features of dermatitis herpetiformis
- Grouped papules/vesicles/urticarial wheals on an erythematous base, associated with intense pruritus, burning, stinging, excoriations
- Lesions grouped,bilaterallysymmetrical
- Common sites: extensor surfaces of elbows/knees, sacrum, buttocks, scalp
Pathophysiology of dermatitis herpetiformis
Transglutaminase IgA deposits in the skin alone or in immune complexes leading to eosinophil and neutrophil infiltration
Investigations of dermatitis herpetiformis
- Biopsy
- Immunofluorescence shows IgA deposits in perilesional skin
Management of dermatitis herpetiformis
- Dapsone (sulfapyridine if contraindicated or poorly tolerated)
- Gluten-free diet for life – this can reduce risk of lymphoma
Diagnosis of Drug Reaction
1-4 = DEFINITE, #1-3 = PROBABLE, #1 only = POSSIBLE
- Temporal relationship between drug exposure and reaction
- Recognized response to suspected drug
- Improvement after drug withdrawal
- Recurrence of reaction on re-challenge with the drug
Clinical features of porphyria cutaneous tarda
- Skin fragility followed by formation often sevesicles/bullae and erosions on photo exposed skin gradual healing to scars, milia
- Periorbital violaceous discolouration, diffuse hypermelanosis, facial hypertrichosis
- Common sites: light-exposed areas subjected to trauma, dorsum of hands and feet, nose, and upper trunk
Pathophysiology of porphyria cutaneous tarda
- Uroporphyrinogen decarboxylase deficiency leads to excess hemeprecursors
Investigations of porphyria cutaneous tarda
- Urine and 5% HCl shows orange-red fluorescence under Wood’s lamp (UV rays)
- 24h urine has elevated uroporphyrins
- Stool contains elevated coproporphyrins
- Immunofluorescence shows IgE at dermal-epidermal junctions
Management of porphyria cutaneous tarda
- Discontinue aggravating substances (alcohol, estrogen therapy)
- Phlebotomy to decrease body iron load
- Low dose hydroxychloroquine
Presentation of exanthematous drug reaction
Erythematous macules/papules +/- scale, symmetrical, trunk to extremities
Typical course of exanthematous drug reaction
7-14d after drug initiation, fades 7-14d after drug d/c
Management of exanthematous drug reaction
d/c drug (weigh risks/benefits) + antihistamines + emollients + topical steroids
Clinical presentation of drug reaction with eosinophilia + systemic symptoms (DRESS)
- morbilliform rash (face, trunk, arms) + can have facial edema
- systemic Features: fever + malaise + arthralgia + cervical lymphadenopathy + internal organ involvement (hepatitis, nephritis, pneumonitis, hematologic abnormalities, thyroid dysfunction)
Typical spread of DRESS
Starts with face/periorbital + spread CAUDALLY + no mucosal involvement
Classic triad of DRESS
Fever + exanthematous eruption + internal organ involvement
Management of DRESS
- Discontinue drug +/- prednisone (0.5mg/kg/d) + consider cyclosporine if severe
- MAY progress to generalized exfoliative dermatitis/erythroderma if drug is NOT discontinued
Clinical presentation of drug induced urticarial angioedema
- Intensely pruritic, well-circumscribed, erythematous, elevated wheals lasting >24hr (unlike non-drug induced urticarial). Individual lesions may coalesce and wax and wane over several hours + angioedema (face and mucous membranes)
- Systemic Features: ~ associated with systemic anaphylaxis (bronchospasm, laryngeal edema, shock)
Management of drug induced urticarial angioedema
d/c drug + antihistamines + steroids + epinephrine if anaphylactic
Clinical features of serum sickness-like reaction
- Morphology: symmetrical cutaneous eruption (usually urticarial)
- Systemic features: malaise, low grade fever, arthralgia, lymph adenopathy
- Time course: appears 1-3 wk after drug initiation, resolve 2-3 wk after withdrawal
Management of serum sickness-like reaction
Discontinue off ending drug ¬ ± topical/oral corticosteroids
What is stevens-johnson syndrome
- Type IV Hypersensitivity Reaction
- A consequence of rapid, synchronous cell death of deeper layer keratinocytes resulting in separation of the skin at the dermal– epidermal junction (therefore subepidermal cleavage)
Clinical features of stevens-johnson syndrome?
- Morphology: prodromal rash (morbilliform/targetoid lesions ± purpura, or diffuse erythema), confluence of flaccid blisters, positive Nikolsky sign (epidermal detachment with shear stress), full thickness epidermal loss; dusky tender skin, bullae, desquamation/skin sloughing, atypical targets. PAINFUL macular exanthem. Most drug rashes are itchy, not painful
- Systemic features: fever (higher in TEN), cytopenias, renal tubular necrosis/AKI, tracheal erosion, infection, contractures, corneal scarring, phimosis, vaginal synechiae
Classification of stevens-johnson syndrome
BSA with epidermal detachment: <10% in SJS, 10-30% in SJS/TEN overlap, and >30% in TEN
Spread of stevens-johnson syndrome
Face and extremities; may generalize; scalp, palms, soles relatively spared; erosion of mucous membranes (lips, oral mucosa, conjunctiva, GU mucosa)
Causes of stevens-johnson syndrome
Often associated with medications (e.g. antibiotics, analgesics, antihistamines, contrast agents)! The most well recognized is SJS/TEN in response to carbamazepine therapy in Han Chinese individuals carrying the HLA-B*1502 allele.
Management of stevens-johnson syndrome
- Discontinue offending drug
- Admit to intermediate/intensive care/burn unit
- Supportive care: IV fluids, electrolyte replacement, nutritional support, pain control, wound care, sterile handling, monitor for and treat infection
- IVIg or cyclosporine or etanercept
Clinical presentation of impetigo
Vesicles, bullae (large vesicles), and pustules which become covered by golden yellow crust (honey brown).
Etiology of impetigo
- Group A beta-hemolytic streptococci, but also staph aureus.
- Certain strains of Group A will cause post-streptococcal glomerulonephritis; uncommon, but can happen during nephritogenic strain epidemics. If suspect endemic like this, follow pt for glomerulonephritis and urinalysis 7 weeks following impetigo. Phage group II staphylococci can cause bullous impetigo.
Investigations of impetigo
Gram stain and culture of lesion fluid or biopsy
Treatment of impetigo
- Remove crusts, use saline compresses, and topical antiseptic soaks bid
- Topical antibacterials (e.g. 2% mupirocin or fusidic acid (Canada only) tid; continue for 7-10d after resolution)
- Systemic antibiotics (e.g. cloxacillin or cephalexin for 7-10d)
Etiology of erysipelas
GAS
Clinical features of erysipelas?
- Superficial cellulitis involving the upper dermis and lymphatics
- Confluent, erythematous, sharp raised edge, warm plaque, well demarcated
- Very painful (“St. Anthony’s fire”)
- Erysipelas is nonpurulent
- Sites: face and legs
- Systemic symptoms: fever, chills, headache, weakness (if present, sign of more serious infection)
- Classic descriptions of erysipelas note “butterfly” involvement of the face