Skin Disorders Flashcards
Bullous Pemphigoid
a) features
b) vs pemphigus
c) causes
d) biopsy features
e) treatment
a) Blistering/bullous skin rash in the flexures and trunk predominantly
- Tends to affect >80 years old (pemphig-old)
b) - PemphiguS affects the Superficial skin (epidermis) and causes lesions and blisters that are easily ruptured (Nikolsky sign); pemphigoiD affects a Deeper layer of the skin, between the epidermis and the dermis, creating tense blisters that do not break easily
- Pemphigus tends to affect the mouth (Pemphi-gustatory); rare in Pemphigoid
- Pemphigus antibodies - anti-desmoglein 1 and 3; Pemphigoid anti-hemidesmosomal antibodies, basement membrane (anti-BPA 1 and BPA 2) and anti-type 17 collagen
c) - Drugs - furosemide, ACE, penicillamine, anti-melanoma drugs
- Pregnancy
(pemphigus may be paraneoplastic - often Non-Hodgkin’s Lymphoma)
d) Subepidermal blister, polymorphous inflammatory infiltrate with eosinophilia;
C3 deposition in pemphigoid and pemphigus
e) Steroids - if <10% BSA give topical, otherwise systemic
Erythema multiforme
- features
- causes
- target lesions (annular with central clearing) in acral sites
- viruses (HSV, HIV), mycoplasma pneumonia, drugs (penicillins, anticonvulsants, sulfonamide, NSAIDs)
Pityriasis Rosea
a) features
b) cause
c) management
d) vs pityriasis versicolor
a) herald patch (ringworm appearance) on the trunk followed by eruption of scaly plaques in “Christmas tree” distribution. non itchy.
b) viral trigger (HHV-7), most common in young adults
c) self resolves within a few weeks without treatment
d) versicolor is caused by fungus - causes depigmentation
Pityriasis versicolor
Caused by overgrowth of commensal yeast malassezia furfur
Presents in young adults often in warm weather or after a sunny holiday
Generally affects the trunk
Lesions often coalesce, may have hypo or hyperpigmentation and fine peripheral scaling
Treatment with antifungals
Pyoderma gangrenosum
- who gets it?
- presentation
- management
a) - Auto-immune: RA, IBD (eg peri-stomal), diabetes
- Haematological malignancy: myeloma, AML, CML, lymphoma
- GPA
b) papule or pustules that break down and form painful necrotic ulcers that rapidly enlarge, with prominent purplish borders
c) steroids, or biologics
(Not antibiotics)
Dermatitis herpetiformis
a) presentation
b) test
c) cautions with dapsone
d) What is DRESS?
e) 2nd line treatment
a) itchy red papular rash especially on buttocks, outer thigh, extensors and scalp
May have GI symptoms also
b) Anti-TTG antibody
c) - pregnancy (increase folic acid to prevent neonatal haemolysis), haemolytic conditions, severe anaemia, neuropathy
- can also cause LFT derangement so needs monitoring
- rarely, can cause methaemoglobinaemia
d) Drug reaction with eosinophilia and systemic symptoms:
- Mobilliform (measles-like) rash with oedema
- Lympadenopathy
- Kidney complications
- Mucosal involvement
May be triggered by certain drugs e.g. dapsone, antiepileptics, antibiotics.
Occurs 3-6 weeks after commencing the drug.
Treated with prednisolone.
If Gluten free diet and dapsone not effective, try oral sulfapyridine. Caution risk of Agranulocytosis
Dermatomyositis
- over 40s with this rash have what chance of underlying cancer? Most likely cancers?
- presentation
- investigations
a) 1/3 have a malignancy: most common Lung, breast, thyroid, gynaecological
b) - Heliotrope rash (periorbital rash red or violaceous +/- associated oedema)
- Gottrons papules on backs of fingers and hands, nail fold inflammation
- Shawl sign (erythema over back and neck)
- Proximal myopathy (if absent - amyopathic dermatomyositis)
c) - CK, ANA, EMG, muscle biopsy and CT TAP (underlying cancer)
- Antibodies specific to DM- anti-TIF1γ, Anti-Mi2
Discoid lupus
a) Presentation
b) Investigations
c) Management
a) - scaly erythematous coin shaped plaques on sun exposed areas (e.g. scalp, face), may have associated alopecia and scarring
- doesn’t have systemic features
b) ANA negative
- Skin biopsy to confirm
c) - Sun block and avoidance
- Highly potent topical steroids (even if on face)
- 2nd line: hydroxychloroquine
Steven-Johnson syndrome
a) Drug causes (NCP LAPSE)
b) Non-drug causes
c) EM minor, EM major, SJS, TEN
d) Chinese increased incidence of TEN with carbamazepine
a) NSAIDs
Carbamazepine
Phenytoin/ Phenobarbital
Lamotrigine
Allopurinol
Penicillin
Sulfa drugs (e.g. co-trimoxazole, thiazides, furosemide, sulfonylurea)
Erythromycin
b) Infections* - mycoplasma, HSV, other
*Note - drug causes much more common in SJS/TEN than in EM minor or major (mostly infective triggers)
c) - EM minor - viral trigger, target lesions, hands and face, no systemic sx
- EM major - plus… systemic features (e.g. fever, arthralgia), mucosal involvement
- SJS - plus… systemic features, truncal involvement, bullae, desquamation, severe mucosal involvement, involves 10-30% body surface area
- TEN - involves >30% body surface area, may involve GI/resp tracts
d) Chinese people commonly have the HLA-B*1502
Porphyria cutanea tarda
a) Cause
b) Presentation vs discoid lupus
c) Investigations
d) Management
a) Deficiency of uroporphyrinogen decarboxylase - usually sporadic but some are inherited
b) - Recurrent photosensitive blistering rash, worse with alcohol. Milia at sites of healing blisters.
- Discoid lupus is also photosensitive but causing erythematous scaly rash on the face/scalp/trunk with scarring alopecia
c) Urinary porphyrins
UROD deficiency test
d) Venesection - aim for ferritin levels <20
Hydroxychloroquine
Iron chelators
Pityriasis lichenoides
a) Trigger
b) Presentation
c) Management
a) Infection e.g. EBV
b) - Papules, then 1cm pustules on abdomen, chest and limbs
- Generally burning rather than itching
- Usually in <30s, more common in males
c) Topical tacrolimus
Cellulitis vs erysipelas
a) Causative pathogen
b) Clinical features
a) Cellulitis - deeper layers of skin, usually legs, usual cause is Staph Aureus
Erysipelas - superficial epidermis, usually face, usual cause is strep pyogenes (GABS)
b) Erysipelas - raised, rapidly enlarging superficial erythema. Skin often devlops vesicles/bullae or skin breaks
Lichen planus
a) 5 Ps, common sites, other fx
b) Treatment
a) - Planar, polygonal, pruritic, purple papules
- Wickham’s striae - fine white lace on the papules
- Common sites: genitals, forearms, sites of trauma/friction (Koebner phenomenon)
- Can affect buccal mucosa
- Can affect scalp and cause a scarring alopecia
b) Topical steroid
Onycholysis: causes
- Trauma
- Skin diseases - psoriasis, lichen planus, scabies
- Infections
- Metabolic - DM, hyperthyroid
- Malignancy
Autosomal dominant condition leading to eruptions of warty brown papules
Darier’s disease
