Dermatology - Eczema, Psoriasis and Infection Flashcards
Main features of eczema
Red, itchy, dry
Physical signs in eczema
Erythema Scale Excoriation Exudate Crusting Hyperkeratosis Lichenificaation
Excoriation
Scratch marks
Hyperkeratosis
Excessive production of epidermis which stays stuck and becomes thick (like on feet)
Lichenification
Increased roughened skin markings due to rubbing
Vesicles
Raised, clear fluid-filled lesion <0.5cm in diameter
Sub erythroderma vs erythroderma eczema
Sub erythroderma (70-90%) Erythroderma (>90%)
Exudate
Fluid oozing which dries to form crust
Who can atopic eczema affect
Adults or children
What are included in atopic disease
Eczema
Asthma
Urticaria
Hay fever
What gene abnormality is accosted w/ atopic eczema
Fillagrin gene abnormalities
Cross hatching in thenar eminence
How does atopic disease manifest in skin
Disruption in barrier function of skin - makes skin ‘leaky’
Typical sites of atopic eczema
Flexures
Different strengths of corticosteroids
Mild (e.g. 1% hydrocortisone) x4 - face
Medium (e.g. eumovate) x4 - flexures
Potent (e.g. betnovate) x4 - limbs
Very potent (e.g. dermovate) - thicker skin e.g. palms and soles
Difference in strength from mild and very potent steroids
64x
Are cushingoid features common w/ topical steroids
No
Asteatotic eczema
Cuased by lack of oil
Usually seen in older people nursing homes or long stay hosp pts
How much does oil production change per year
1% drop with age
Treatment of asteatotic asthma
Bathes less often, short and cooler
Use less detergent
Apply oil to skin or emollients
Keep air moist in home
Irritant contact eczema
Chemicals will irritate skin cells deepening on exposure and conc
Irritation isn’t same as allergy (due to immune process)
What can irritant contact eczema present as
Looks same as atopic eczema - hx is imperative
Allergic contact eczema
Comes on a few hrs to 96 hrs after contact
Investigate w/ patch tests
Common skin allergens
Nickel
Fragance
Chromate
Formaldehyde
Ix for allergic contact dermatitis
Patch tests
Apply patches day 1
Remove day 3
Read days 3 and 5 - redness, itch, scale
Select batteries according to hx and distribution
Why is diagnosing varicose eczema important
Commonly breaks down (infection or scratching) to form leg ulcer
Treatment of venous stasis
Lose wt Exercise Elevate legs Avoid standing/ sitting for long periods Compression bandages VV surgery
Eczema and scratching
Scratching causes lichenification long term
Excoriated skin exudes and crust
May become secondarily infected
What type of lichenification can be caused by scratching
Lichen simplex
Why are bandages used in eczema
Stops scratching and break scratch/ itch cycles
Paste bandages of wet wraps can be used in children
When should bandages not be used for eczema
If eczema is infected
Infected eczema (bacterial)
Often due to scratching and causes impetiginous change
Commonly due to presence of Staph A
Produces impetiginized eczema
Impetiginized eczema
Produces yellow (aureus) crust and/ or blisters of impetigo
Infected eczema (viral)
Herpes simples - causes cold sores
Also infects eczema on head and neck
Eczema herpeticum
Eczema herpeticum
Erythematous, vesicular, well defined crusted blisters
Discoid
Coin shaped
Discoid eczema
Variant of bacterial infected eczema
What is discoid eczema often confused with
Psoriasis
But has follicular areas, less well defined and lacks psoriasis scale usually
What does discoid eczema often co-exist with
W/ areas of follicular eczema
Treatment for discoid eczema
Abx and antiseptic/ steroid combi needed
Pompholyx eczema
Little blisters down the sides of fingers
Intensely itchy
Episodic
Causes of pompholyx eczema
Allergy or endogenous (atopic) or both
What is seborrhoeic eczema sue to
Sensitivity to yeast on skin
Not due to yeast in diet
Epidemiology of seborrhaeic eczema
Very common (esp in older pts)
What can negatively affect sebborhoeic
Made worse by stress
Severe in HIV disease
What does seborrhoeic eczema rash
Dandruff
Rash on eyebrows, nose, nasolabial folds and flexures
Treatment of seborrhoeic eczema
Treat w/ topical or systemic antifungals +/- corticosteroid creams
General treatment of eczema
Emollients if dry Antiseptic soaks if oozing Topical steroids depending on degree of infl Abx course if infected or discoid Antifungals if seborrheic Antivirals if herpes Bandaging if scratching Elevation etc in stasis
More aggressive treatments for eczema
PUVA
Oral alitretinoin
Oral azathioprine, ciclosporin - broad spectrum immunosuppressants
Ddx of eczema
Scabies Fungal infection in hands Psoriasis Drug eruption Rarer diseases e.g. bullous pemphigoid, dermatitis herpetiformis, mycosis fungoides
Scabies as ddx of eczema
Burrows between the fingers and friends/ family usually affected
Fungal infection in hands as ddx of eczema
Often unilateral (one hand, tow feet)
Psoriasis as ddx of eczema
Can be itchy but different Physical signs
Tineal (fungal) hand infection
Fine, silver scale in creases, lack of cracking and often unilateral
Take fungal scrapings if unsure
Psoriasis and discoid eczema
Similar, nail changes can occur in both
But different physical signs, look at scalp
Skin functions
Protective barrier Temperature regualtion Sensation Immunosurveillance Appearances/ cosmesis Waterproofing
Cell types in epidermis
Keratinocytes
Langerhans’ cells
Melanocytes
Merkel cells
Keratinocytes function
Protective barrier
Langerhan’s cell function
Present antigens and activate T-lymphocytes for immune protection
Melanocytes function
Produce melanin, which gives pigment to the skin and protects the cell nuclei from UV radiation-induced DNA damage
Merkel cells
Contain specialised nerve endings for sensation
How many layers does the epidermis have
4, each representing a different stage of maturation of the keratinocytes
Epidermal layers
Stratum basale (basal cell) Stratum spinosum (pickle cell layer) Stratum granulosa (granular cell layer) Stratum lucidem - found in thicker skin Stratum corneum (horny layer)
Come Let’s Get Sun Burnt
Stratum basale
Actively dividing cells
Deepest layer of epidermis
What is found in the stratum spinosum
Differentiating cells
Cells are bound together by desmosomes
Function of stratum granulosum
Secrete lipids in extracellular areas
Stratum corneum
Layer of keratin
Most superficial layer of epidermis
Lichen planus
C/c autoimmune disorder affecting skin (esp flexor surfaces), mucosa and genitals
Scaliness and itchy skin may be seen
A/c px of lichen planus
Affects flexor surfaces
Itchy and can be painful
Distinct, often round, purpuric, raised lesion
Healing of lichen planus lesions
Aa the initial lesions heal, leave a small, flat brown discoloured circle
Mx of lichen planus
Many cases resolve spontaneously within a yr, can give topical steroids
Epidemiology of granuloma annular
Relatively common disorder
Affects children and young adults
Granuloma annulare px
Localised ring of beaded papules on the extremities
Mx of granuloma annulare
Many cases resolve spontaneously within a year
What does the efficacy of a topical drug depends on
Its internet potency and its ability to penetrate skin
Factors affecting penetration of topical drugs
Conc of medication
Thickness and integrity of stratum corneum
Frequency of application
Compliance
Factors affecting pharmcokinetics of topical drugs
Anatomy/ site
hydration of skin
Type of compound - hydrophilic vs phobic
Age
Common drugs given for derm
Steroids Retinoids Calcineurin inhibitors Topical abx Imiquimod Sunscreens
Why are steroids given in derm
Effective at reducing symptoms tops of infl, but dint address underlying cause of disease
Which dermatoses are most responsive of steroids
Psoriasis
Atopic dermatitis
Topical calcineurin inhibitors
NSAIDs that reduce pro-infl cytokines responsive for itch and rash of atopic dermatitis
Imiquimod
Topical immunotherapy (enhances cell-mediated immune response)
Indications of imiquimod
Genital warts
Superficial BCC
Actinic keratosis
Clinically important immune deficiency as a rare cause of skin disease
Infections in HIV (cold sore, thrush)
Skin cancer sin organ transplant recipient
Congenital deficiencies e.g. Wiskott-Aldrich syndrome
Allergy vs autoimmunity
Both are examples of overactivity/ abnormal regulation of immune system
Allergy - bad clinical reaction to immune system to environmental antigens (allergens)
Autoimmunity - bad clinical reaction by the immune system to self-antigens (auto antigens)
Basis of hypersensitivity reaction in skin
Immunological reactions cause disease by promoting infl
Infl leads to diff clinical patterns of disease
A pattern of disease may be caused by more than one type of immunological reaction
What is urticaria characterised by
Short-lived swellings caused by plasma leakage from capillary blood vessels in and below skin
Main mediator for plasma leakage in urticaria
Histamine - Type I HS or Type V (in response to autoantibodies)
What is histamine released from in Type I HS reaction
Most cells (along w/ other mediators) Degranulation of mast cells may be triggered by allergens or autoantibodies
Bullous pemphigoid
Acquired blistering condn of the skin, sometimes mucous membranes
What type of HS is bullies pemphigoid
II
Autoantibodies against one or more antigens in the hemidesmosomes
Viral skin infections
Herpes simple
Herpes zoster or shingles
Viral warts
Molluscum contagiosum
Pathogen causing Herpes simplex
HSV-1 or HSV-2
Features of cold sores
Painful (neuropathic - tingling), self-limited
Often seen in recurrent dermatoses
Prevalence of HSV1 and HSV2
HSVI - orofacial (80-90%), sometimes genital
HSV2 - genital (70-90%), sometimes orofacial
Transmission of HSV
Direct contact at a mucosal surface or on site of abraded skin
Symptoms and signs of herpes simplex
Painful (sore) grouped vesicles on erythematous base –> crust + erosions
Dx of HSV
Usually clinical
Direct microscopy (Tznack smear)
Viral culture
Treatment of genital herpes simplex
Topical acyclovir 5% ointment
SystemicL: aciclovir - 200mg 5x/day for 5/7
Prophylaxis: 200mg TDS for 6/12 - 12/12
Alternative treatments of HSV
Famciclovir
Valacyclovir
HSV in immunocomoproimised
Lesions can be extensive or c/c
Prognosis of HSV
HSV persists in Doral root ganglia for life so tends to reoccur
Compliactions of HSV
Erythema multiform
Eczema herpeticum
Affects CNS
Definition of herpes zoster
A/c painful dermatomal dermatoses
Prevalence of herpes zoster
10-20% of adults have hx of disease
Transmission of herpes zoster
Reactivation of latent VZV in a sensory ganglion (previously had chicken pox)
Symptoms and signs of shingles
Pain in a demrtaomal or band like pattern
Followed by group of grouped vesicles on erythematous base –> crusting, fever and malaise
Dx of shingles
Viral culture
Tzanck smear
DDFA
Serology
Treatment of shingles
Analgesics
Aciclovir (effective 24-72hr of disease onset) 800mg 5x/day for 5/7
Prognosis of shingles
Symtoms resolve in 2-3/ 52
Complications of shingles
Post-herpetic neuralgia
Cranial nerce syndromes e.g. Ramsey hunt syndrome
In immunocompromised: disseminated form
Pathogen causing viral warts
HPV
Viral wart definition
Benign epithelial growth (premalignant on genitals and immunosuppressed - 16-18 subtypes )
Prevalence of viral warts
5% of population
Transmission of viral warts
Skin to skin contact
Sexually (condyloma acuminatum)
Symptoms of viral warts
Hyperkeratotic, flesh-coloured papule and/or plaque studded w/ small dots (thromboses capillaries)
Dx of viral warts
Clinical appearance
Histology if any doubt
Treatment of viral warts
No treatment
Topical salicylic acid
Cryosurgery
Prognosis of viral warts
Remove spontaneously within yrs
In immunocompromised; warts are resistant
Complications of viral warts
SCC genitals e.g. 16-18 subtypes
Pathogen causing molluscs contagious
Molluscum contagious virus (MCV) (poxvirus)
Definition of molluscum contagiousm
Benign self-limited papular eruption
Prevalence of molluscum contagiousum
Common in children and sexually active adults
Transmission in mollucsum contagiosum
Skin to skin contact
Symptoms in mollucscum contagiousm
Smooth flesh-coloured, dome-shaped, umbilicate papules contain keratotic (cheesy) plug
Dx of MCV
Clinical appearance
Prognosis of MCV
Spontaneous resolution
Treatment of MCV
May not be necessary
Cryotherpay
Curettage
May use topical immunomodulator drugs
Bacterial skin infections
Impetigo Folliculitis, furunculosis, carbunculosis Ecthyma Erysipelas and cellulitis Necrotizing fasciitis
Pathogen causing impetigo
Staph A > Strep pyogenes
Impetigo
Superficial skin infection
Prevalence of impetigo
1%
Transmission of impetigo
S. aureus and S. pyogenes are infrequent resident flora of skin
Symptoms of non-bullous impetigo
Vesicles or pustules or erythemautos skin –> erosions –> golden-yellow crust
Symptoms of bullous impetigo
Flaccid bullae w/ clear, yellow fluid (S. aureus) –> erosions —> golden-yellow crust
Dx of bullous impetigo
Clinical px
Confirmation by culture
Treatment of bullous impetigo
Topical aciclovir and/ or systemic abx e.g. topical mupirocin TDS for 7-10days or systemic beta lactams
Pathogens causing infection of hair follicles
Staph A
Psuedomonas aeruginosa
Folliculitis, furunculosis, carbunculosis
Transmission of infection of hair follicles
S. aureus is infrequent resident flora of skin
Exposure to P. aeruginosa in hot tubs or swimming pools
Different infections of fair follicles
Folliculitis - most superficial
Furunculosis
Carbunculsosis - deepest
Dx of infection of hair follicles
Clinical px
Conformation by culture
Treatment of infections of hair follicles
Topical treatments w/ 1% clindamycin or 2% erythromycin
Systemic antistpah abx, incision and drainage
Symptoms in folliculitis
Generally asymptomatic
But may be pruiritis and painful
Furunculosis
Tender, erythematous, fluctuant nodules that rupture w/ purulent discharge
Carbunculosis
Larger & deeper infl nodules often w/ purulent drainage
Ecthyma
Deep infection of the skin (down to epidermis) that causes a shallow, round, punched out ulcer
Pathogens causing ecthyma
Staph A
Strep pyogenes
Botha re infrequent resident flora of skin