Pathology Flashcards
What is the visual presentation of hyperkeratosis
A scaly skin rash
Build up of keratin layer
What are the 4 main reaction patterns of inflammatory skin diseases
Spongiotic-intraepidermal oedema e.g. eczema
Psoriasiform- elongation of the rete ridges e.g. psoriasis
Lichenoid-basal layer damage e.g. lichen planus and lupus
Vesiculobullous- blistering e.g. pemphigoid, pemphigus
What is the characteristic of lichenoid disorders
Damage to basal epidermis - between epi and dermis
Most common condition is lichen planus
Can be a lichenoid drug reaction
How does lichen planus present
Itchy flat topped pink/purple papules
Very ithcy
Affects wrists, forearms, shins and ankles
May get lacy, white streaks in cheeks or on papules- Wickham’s striae
what is the main feature of immunobullous diseases
Blisters
vesicles and bullae
What is pemphigus
Rare autoimmune bullous disease
Autoantibodies cause damage to the junctions between skin cells - intrepidermal
Loss of junction integrity causes severe blisters
How can you treat pemphigus
Responds to steroids
What is the most common subtype of pemphigus
Pemphigus vulgaris
80% of cases
Describe the cause of pemphigus vulgaris
IgG autoantibodies made against desmoglein 3 which forms the desmosomes
Immune complexes form and complement is activated
Proteases are released and dissolve the attachments between cells - leads to acantholysis
Occurs within the epidermis itself
what is acantholysis
Breakdown of intercellular adhesion sites
common to all types of pemphigus
What causes bullous pemphigoid
IgG antibodies attack the hemidesmosomes that attach the basal cells to the basement membrane
This breaks down the DEJ and causes separation of dermis and epidermis
Complement is activated and the surrounding tissues are damaged
How does bullous pemphigoid present
Can present with itchy red plaques and papules before the blisters develop
Subepidermal blisters - deep
Large, tense blisters on normal, red or urticarial base
When they burst, they leave erosisons but do not scar
Unlikely to affect mucosa (mouth only if at all)
typically localised to one area or widespread on trunk/ limbs
Nikolsky sign negative
What would show up if you did immunofluorescence on a bullous pemphigoid sample
Linear pattern of IgG antibodies would show up along the basement membrane - solid typically green line alone BM
Would also pick up complement
What condition is dermatitis herpetiformis associated with
Coeliac disease
Personal or family history
How does dermatitis herpetiformis present
Extremely itchy lesions - typically preceeds blisters
Small blisters on erythematous urticarial base - often scratched off leaving crusts or excoriation
Symmetrical
Often affects the elbows, extensor forearms, knees, buttocks, face and scalp
The hallmark is papillary dermal microabscesses
Which HLA group is dermatitis herpetiformis associated with
HLA-DQ2 haplotype
What would a dermatitis herpetiformis sample look like under immunofluorescence
IgA deposits seen at the tips of the dermal papillae
Granular IgA deposits
What is the aetiology of acne
It is a chronic inflammatory disease of the pilosebaceous units.
Increased androgens during puberty cause increased activity of sebaceous glands
Keratin and sebum plugs the pilosebaceous unit
Glands get blocked, inflamed then rupture
Infection with other bacteria (p acnes) causes further inflammation
What is the normal distribution of acne
face, upper back, anterior chest
High concentration of sebaceous glands
What is the clinical presentation of rosacea
Recurrent facial flushing - exacerbated by sudden change in temperature , alcohol & spicy food
Erythema
Visible blood vessels
Pustules and papules
Thickening of skin Rhinophyma - enlarged red nose
Affects nose, chin, cheeks and forehead
How can you differentiate between acne and rosacea
Rosacea does not have comedones - black/white heads
Also normal sebum excretion rates
What are some triggers of rosacea
Sunlight Alcohol Spicy foods Stress Sudden temperature changes
List some topical treatments for acne
Bezoyl peroxide
Antibiotics
Retinoids
How do topical retinoids work
Dry skin up by shrivelling the sebaceous glands and reducing secretion
Anticomedonal
Describe the presentation of acne vulgaris
Comedones - black/white heads
Pustules and papules
cysts
erythema
What is a potential complication of acne
Scarring
Can be atrophic (shallow/ice pick) or hypertrophic (keloid)
Usually after deep lesions
Where on the body does rosacea normally appear
Nose, chin, cheeks and forehead
How can you treat rosacea
Reduce exposure to triggers - diet, wear suncream Topical = metronidazole, ivermectin Oral tetracycline - long term Roacccutane if severe Vascular laser for telengectasia Rhinophyma - surgery
How do you treat lichen planus
Symptomatically
Usually burns out after 12-18 months
Can use topical steroids
Oral if very severe
what is Nikolsky’s sign
When the top layer of skin slips away from the lower ones when rubbed slightly
Positive in pemphigus
Which areas of the body are typically affected by pemphigus vulgaris
Scalp, face, axillae, groins Mucosal involvement (eyes, genitals) is very common May also appear on pressure points
Which condition has higher risk, pemphigus or pemphigoid?
Pemphigus
Very high mortality if untreated - 75-99%
How do you treat pemphigus
First line - oral steroids (pred)
Typically start steroid as inpatient – may be IV
Then can add another immunosuppressive agent - usually azathioprine
Topical steroids and anaesthetics are symptomatic treatment only
List physical causes of skin blistering
Insect bites
Burns
Friction - particularly in elderly as friable skin
List infectious causes of skin blistering
HSV – cold sores, eczema herpeticum
VZV – chickenpox, zoster
Coxsackie virus – hand-foot-and-mouth disease
Staph aureus – bullous impetigo, SSSS
Strep pyogenes – bullous cellulitis
List genetic causes of skin blistering
Epidermolysis bullosa (EB)
Which drug reactions can cause skin blistering
EM / Stevens-Johnson syndrome
Toxic epidermal necrolysis (TEN)
Fixed drug eruption
What is the role of desmosomes
Hold adjacent epidermal cells together
What is the role of the hemidesmosomes
Hold the epidermis to the dermis at the DEJ
How would you investigate suspected bullous disease
History and examination
Bloods – Usual set with inflammatory markers – ESR/CRP
May do swabs to rule out infection
Biopsy with IMF - this will be your diagnostic test
which age group is most affected by bullous pemphigoid
Age >60 years in majority
How do you treat bullous pemphigoid
Topicals: emollients, topical antisepsis / hygiene measures
First-line – topical steroid + doxycycline for localised disease
Second line – oral steroid + steroid sparing like doxy for generalised disease
May use doxy alone if disease is not severe
Rest are 3rd line onwards that isn’t responding - azithioprine, dapsone, biologics
Bullous pemphigoid is typically self limiting - true or false
True
However it is chronic and can take months to years to resolve without treatment
Treatment reduces recovery to 3-6 months
which age group is most affected by pemphigus vulgaris
Usually a disease of middle age
How does pemphigus vulgaris present
Flaccid vesicles/bullae
Includes oral, throat and genital lesions
They rupture easily leaving raw, denuded erosions
Nikolsky sign positive
How would pemphigus vulgaris present on immunofluorescence
Would see IgG deposits outlining epidermal cells
Looks like chicken wire
Which age group is most affected by dermatitis herpetiformis
Mainly young adults
Can affect all ages though!
How would you investigate dermatitis herpetiformis
Coeliac serology – IgA antibodies to tissue transglutaminase (tTG)
Histology of lesion- subepidermal blisters, microabscesses in dermal papillae
Biopsy uninvolved skin for detection of granular deposits of dermal papillary IgA on immunofluorescence
Small intestinal scope + biopsy
How do you treat dermatitis herpetiformis
Gluten-free diet - mainstay
Drugs: dapsone, Tetracyclines
How do you treat mild acne
Topical treatment only
e.g. Benzoyl peroxide
Topical antibiotics, retinoids
Range of anti-comedonal, inflammaotry and microbial effects
What are comedones
Blocked pores bascially
If closed - whitehead
If open - blackhead
What can cause an increase in sebum production
Androgen effect as sebaceous unit had androgen receptors
Increased androgen production - seen in puberty or androgenic hormone imbalance in females
Increased availability - decreased SHBG
Increased androgen receptor responsiveness
The more bacteria present in acne, the worse it is - true or false
False!
No relationship between # of bacteria and acne severity
More related to amount of sebum and ductal cornification
Which bacteria commonly colonise acne
Propionobacterium acnes
Staph. epidermidis
Malassezia furfur
How do you grade acne
Mild- scattered papules and pustules
Moderate- numerous papules, pustules and
mild atrophic scarring
Severe - as above, cysts, nodules and significant scarring
What factors can aggravate acne
Poor diet Being pre-menstrual = common to flare Sweating UV Steam or oil in environment Stress
How do you treat moderate acne
Topical treatment and oral antibiotics or Dianette® (females)
How do you treat severe acne
Isotretinoin (Roaccutane®)
What are the side effects of benzoyl peroxide for acne
Erythema and peeling
Bleaches clothes, hair, bedlinen and towels
Retinoids should be avoided in pregnancy - true or false
True
Systemic absorption of topicals not significant but still avoid
What are the side effects of topical retinoids for acne
Stinging, irritation, erythema and peeling
Which antibiotics are used for acne
Topical:
Erythromycin
Tetracycline
Clindamycin
Oral: Erythromycin Oxytetracycline Doxycycline Minocycline - needs LFT monitoring
What is the main skin side effect of tetracyclines
Photosensitivity
If antibiotic therapy isnt working for acne should you try another
Yes
Try a second antibiotic after 3-6 months
Can contraception be used to treat acne
Yes - combined pills
Typically use dianette
Oestrogen decreases androgen production
Takes 6 months to lower sebum though
Progesterone rich / Only contraceptives may exacerbate acne
What are the indications for starting someone on roaccutane
Nodulo-cystic acne
Inadequate response to conventional therapy
Relapse after adequate antibiotics
Significant scarring
Severe psychological impairment (dysmorphophobia)
post-inflammatory hyperpigmentation
How does roaccutane work
Reduces sebaceous gland activity
List side effects of roaccutane
Dry skin, lips, eyes, nose Skin fragility Hyperlipidaemia Abnormal liver function Teratogenesis- contraception Mood alteration Arthralgia Acne fulminans Hair thinning Benign intracranial hypertension
How does tuberous sclerosis present in the skin
Multiple hamartomas Angiofibromas Peri-ungual fibromas Shagreen patches Ash leaf macules
What causes tuberous sclerosis
Autosomal dominant mutation
2/3 are de-novo
What causes neurofibromatosis
Autosomal dominant
Mutation in neurofibromin gene (tumour suppressor) on chromosome 17
How does neurofibromatosis present in the skin
Neurofibromas
Cafe au lait macules
Axillary freckling
Lisch nodules
List skin manisfestations of diabetes
Infections
Leg ulcers and other complications
Some specific disease related to diabetes - Necrobiosis Lipoidica etc
What is erysipelas
skin infection in upper dermis - typically strep
Seen in diabetics
Confluent erythema
Well demarcated
Not raised, scaly or crusty
Would be tender, hot, painful, patient may feel unwell
How do you treat erysipelas
Need oral or IV antibitoics as deep
Would probably use IV if on the face/periorbital
Candida is common in diabetes - true or false
True
Occurs in warm moist areas
Also seen around nails
Hyperglycaemia favours growth
Describe the appearance of Necrobiosis Lipoidica
Bilateral lesions - tyipcally on shins
Smooth skin surface = deeper issue
Epidermal issue will typically be dry and scaly
Erythema and yellowing seen - subcutus peeks through
What causes Necrobiosis Lipoidica
Technically unknown
Most patients are diabetics - ?microvascular cause
Granulomatous inflammatory reaction around destroyed collagen
How do you treat Necrobiosis Lipoidica
Inject steroids around lesion
Can use tacrolimus - calcineurin inhibitor
How might psoriasis present in the nails
Pitting
Onycholysis (lifting of the nail plate off the nail bed)
Subungual hyperkeratosis– keratin build up below the nail
Longitudinal ridging
Thickening
Crumbling
Colour changes
How can you treat psoriatic nail disease
Topical steroids
Intralesional if a few nails affected
Calcipotriol
PUVA - systemic psoriasis treatment
How do you diagnose fungal nail disease
Take clippings
Assess for skin involvement
How do you treat fungal nail disease
Topical or oral antifungals
How does fungal nail disease present
Thickened nails
Brittle
Yellow discoloration
What is a subungual haematoma
Bleeding under the nail
Typically after obvious trauma but repeated microtrauma can be enough
What must be ruled out before diagnosing simple subungal haematoma
Subungual melanoma
They can bleed too
Dermoscopy can help clarify
How does subungal melanoma present
Irregular pigmentation under nail Typically a brown/black stripe down nail Extends to involve proximal nail fold May bleed, ulcerate, Abnormalities of the nail plate
How do you manage subungal melanoma
May require excision of the entire nail apparatus if not amputation