derm Flashcards
what is the immune response in atopy? how does that play a role in dermatitis
CD4+ Th2 lymphocytes detect allergen causing exaggerated igE response to allergen (perfume, foods, clothes)
how does genetic play an role in atopic dermatitis
mutation of FLG gene that encode for filaggrin (protein for skin barrier)
what are the histological progression in atopic dermatitis?
- inflammatory infiltrate of CD4+ Th2 lymphocytes in the upper dermis which can diffuse into epidermis
- keratinocyte apoptosis
- Spongiosis-> vesicles
define keratocyte apoptosis in context of dermatitis
- process that regulates cell death
- can be activated by inflammation and help attract more inflammatory cells
define spongiosis
- intercellular edema or accumulation of fluid between the cells of the epidermis
- enough fluid=vesicle with WBC and proteinaceous fluid
how does keratinocyte apoptosis lead to spongiosis
As keratinocytes die and become detached from each other, the spaces between them fill with fluid, leading to spongiosis
what are the histological changes in chronic atopic dermatitis
lichenification, plaques
Symptoms of dermatitis in acute vs chronic phase?
- Acute: oozing, vesicles, swelling, blistering
- Chronic: plaques, skin thickening
children vs Enfant presentation of atopic dermatitis & associated conditions
- Children: dry, itchy, erythematous rash, no well defined border in flexor areas (ie, bends of elbow, behind knees)
- babies: face, trunk & extensor areas
- May also have asthma or allergic rhinitis (history of atopic disease)
How is the severity of atopic dermatitis/eczema defined?
- Mild: localized areas of dry skin, infrequent itching
- Moderate: localized areas of dry skin, frequent itching, redness
- Severe: widespread areas of dry skin, excessive itching, redness
what are the step by step treatments of atopic dermatisit/ eczema
- Emollients (ie, Dermol 200, E45 lotion)
- Topical hydrocortisone
- Topical betamethasone or clobetasol (can be titrated up except in private areas)
- Topical calcineurin inhibitors (inhibition of T-lymphocytes activation)
- phototherapy, systemic therapy
what are the primary and secondary complications of atopic dermatitis
- Primary infection: eczema herpeticum
- Secondary infection: staph aureus (crusty, oozing rash)
what is eczema herpeticum?
skin infection caused by HPV 1 & 2
seen in children with atopic eczema
what is the presentation of eczema herpeticum
rapid progressing painful rash with punched out erosions and vesicles
what is the treatment for eczema herpeticum
IV aciclovir
What are the cause & disease associated with dermatitis herpetiformis?
- deposition of IgA in the dermis
- associated with celiac disease (weight loss)
what is the presentation of dermatitis herpetiformis
Itchy small red vesicular lesions on extensor surfaces (ie, elbow, knee, butt, torso)
what is this?
dermatitis herpitformis
What is the diagnosis of dermatitis herpetiformis?
- Skin biopsy: igA in a granular pattern in upper dermis
- bloods: Anti-tissue transglutaminase (anti-TTG)
what is the treatment for dermatitis herpetiformis
gluten free diet
dapsone
What is the cause & associated conditions of seborrhoeic dermatitis?
- Inflammation from proliferation of Malassezia furfur fungus
- HIV, Parkinson’s disease
what are the symptoms of seborrhoeic dermatitis
itchy lesions on sebum-rich areas (ie, scalp, around eye, nose, ears)
may cause infections
How is seborrhoeic dermatitis treated?
- zinc pyrithione (‘Head & Shoulders’)
- topical ketoconazole, Topical steroids for short periods
how is seborrhoea dermatitis treated in babies
baby shampoo & oil, mild topical steroid (1% hydrocortisone)
what is the cause of irritant contact dermatitis
non-allergic reaction to weak acids or alkalis (ie, soap)
what is the presentation of irritant contact dermatitis
usually on hands, erythema will be present but usually no crusting and vesicles
cause & symptoms of allergic contact dermatitis
- type 4 hypersensitivity
- acute weeping eczema (dry, rashes, erythema, crusting & vesicles),
- ie, hairline & scalp following hair dye use
investigation & treatment allergic contact dermatitis
- skin patch test
- topical potent steroids (betamethasone)
can you define psoriasis?
- Epidermal proliferation/ thickening esp in keratin layer
- triggered by immune cells causing scaly plaques
what are the causes of psoriasis?
- Genetics: HLA-B, identical twins
- activated by Environmental trigger: trauma, injury, infection, sunburn
explain the pathophysiology of psoriasis
- environmental trigger
- keratinocytes to release chemicals that activate Th 1 & Th17 lymphocytes and neutrophils
- inflammatory response and keratinocyte proliferation
what is the function of T cells (Th1 and Th17) in activating psoriasis
- trigger inflammation
- keratinocyte growth & division
- breakdown of the protective barrier.
what is the function of neutrophils in activating psoriasis
- attracted by complement system to keratin layer/ stratum corneum
- build up forming muno micro abscess
- causes keratinocyte proliferation
what is the function of the complement system
innate immune system
helps to eliminate pathogens and damaged cells from the body.
what are the histological presentations of psoriasis
- parakeratosis: nuclei in keratinocytes due to rapid differentiation
- micro-abscess: retention of neutrophils
- elongated rete pegs: epidermis concave down to dermis become thicker and longer
What is the typical presentation of psoriasis? (skin and nail)
- raised, itchy, scaly, well-defined plaques w/ symmetrical distribution in the scalp, extensor surfaces, trunk, gluteal
- Nails: hyperkeratosis, pitting
What are the two signs of psoriasis?
- Koebner phenomenon: psoriasis that develops in an area of trauma
- Auspitz sign: bleeding points where surface scale is removes
what is plaque psoriasis
- Plaque psoriasis: well-demarcated red, scaly patches affecting extensor surface, sacrum and scalp
what is flexural and guttate psoriasis
- Flexural psoriasis: skin is smooth
- Guttate psoriasis: many small red psoriatic rash on torso/ trunk & limb, triggered by streptococcal infection
What are the exacerbating factors of psoriasis?
- trauma, alcohol
- Beta blockers, lithium, chloroquine, hydroxychloroquine, ACE inhibitors
- Withdrawal of systemic steroids
What is the management plan for psoriasis?
- topical Potent corticosteroid + vitamin D analog applied once per day
- Vitamin D analogue twice
- topical Potent corticosteroid twice for 4 weeks
(emollients given to all)
give me an examples of topical potent corticosteroid and vitamin D analogue combo
topical betamethasone + calcipotriol
What is the cause + patient profile of impetigo?
- staph aureus or strep pyogenes
- Children during warm weathers, very contagious spread via toys & clothing
what is the presentation of impetigo
- Golden-crusted skin lesions and red sores around the mouth, Face, flexures limbs
what is this?
impetigo
what is the investigation for impetigo? when is it done?
- clinical diagostic
- bacterial swab for culture if its extensive or severe, suspect MRSA (antibiotic resistant bacteria), recurrent
What is the treatment for impetigo? Can the patient go to school?
- hydrogen peroxide 1% cream
- topical fusidic acid
- Oral flucloxacillin or erythromycin
(No school until lesions are crusted & healed or 48 hours after starting antibiotics treatment)
What is the typical presentation of basal cell carcinoma skin?
- Rodent ulcer that is slow progressive
- Telangiectasia, ill- defined border
- papule then becomes nodular (raised)
What is the histological presentation of basal cell carcinoma skin?
- Basal nest in the dermis
- Irregular strands invading dermis and palisading nucleus
What are the risk factors and treatment of basal cell carcinoma skin?
Sun exposed skin (scalp, arms)
Routine referral
Surgical excision
Topical imiquimod if no risk of metastasis
What are actinic keratoses?
- Partial dysplasia of epidermal keratinocytes due to chronic sun exposure
- Less than 1% may develop into squamous cell carcinoma
What is the presentation of actinic keratoses?
- Scaly erythema papules or patches, gritty and rough
- Occurs on sun exposed skin like scalp, face, hands, ear
What is the treatment for actinic keratoses?
- Sun avoidance and sunscreen
- Fluorouracil cream
- Topical diclofenac and imiquimod
- Cryotherapy
What is bowen’s disease
- Full thickness dysplasia of epidermal keratinocytes
- can develop in squamous cell carcinoma (5-10%)
- Seen commonly in fair skinned women
What is the typical presentation of bowen’s disease
- Women (fair skin, red hair) present with slow growing lesion
- Scaly red patch/ plaque, well-demarcated with irregular border
Are there any variants of bowen’s disease?
- Neoplasia in genital mucosa (vulval, penile, anal, intraepithelial)
- Linked to HPV-16 and 18, common in HIV
How is Bowen’s disease managed?
Topical 5- fluorouracil
Cryotherapy and excision
What is the typical presentation of squamous cell carcinoma of the skin?
- Rapid expanding ulcerative nodule w/ well defined border
- May bleed, central erythema, red scaling plaques
- Can be on face, lip, ear
What are the risk factors of squamous cell carcinoma of the skin?
- Sun exposed skin
- Immunosuppression (HIV, renal transplant)
Smoker - Pre-malignancy: actinic keratosis and Bowen’s disease
What is the treatment for squamous cell carcinoma of the skin
Surgical excision
4mm margin for -20mm
6 mm margin for +20mm
What is the typical presentation of lichen planus?
- Itchy papular rash in palms, forearm, legs flexor surfaces, gentility
- Polygonal, violaceous papules
- White lines in buccal mucosa in mouth
What is the treatment for lichen planus?
- Potent topical steroids (ie, betamethasone, clobetasone)
- Benzydamine mouthwash or spray for oral lichen planus
What is the cause and risk factor of cellulitis?
Mainly Strep pyogenes
staph aureus
Risk factor: Diabetes
What are the clinical presentations of cellulitis?
Swelling in legs
Macular hot erythema with ill defined margins that spread
Fever, rigors, nausea
what is this?
cellulitis
What are the investigations for cellulitis?
- Clinical diagnosis, ERON classification
- Blood culture/ swab only if patient is not responding to treatment or atypical presentation
What is the management for cellulitis?
- Rest, elevation, analgesia, splint
- Flucloxacillin
- Doxycycline, clarithromycin for pen allergy
- IV flucloxacillin (confusion, tachycardia, sepsis)
