Title: Dermatology

Q: Flexural distribution rash
A: Eczema, candida

Q: Sun exposed rash distribution
A: SLE, drug-induced photosensitivity, porphyria, sunburn, viral exanthem

Q: Distal extremity rash distribution
A: Eczema
Viral exanthem
Atopic dermatitis
Contact dermatitis
Gonococcal

Q: Clothing covered distribution of rash
A: Contact dermatitis
Folliculitis
Psoriasis

Q: What does guttate mean?
A: Scattered

Q: Papule vs nodule
A: <5mm (same as vesicle) vs larger

Q: Vesicle size?
A: <5mm

Q: Macules DDx
A: Drug eruption
Rheumatic fever
Secondary syphilis
Viral exanthem
Meningococcaemia
Ecchymosis
Vitiligo
Tinea versicolour
Cellulitis

Q: Papule DDx
A: Acne
BCC
Melanoma
Warts
Molluscum contagiosum
Skin tags
Urticaria
Eczema
Folliculitis
Insect bite
Vasculitis
Psoriasis
Scabies
Erythema multiforme
Gonococcaemia

Q: Plaque DDx
A: Eczema
Pityriasis rosea
Tinea corporis
Tinea versicolour
Psoriasis
Seborrhoeic dermatitis
Urticaria
Secondary syphilis
Erythema multiforme

Q: Wheal DDx
A: Urticaria
Angioedema
Insect bite
Erythema multiforme

Q: Vesicular rash DDx
A: Herpes
VZV
Impetigo
Thermal burn
Friction burn
TENS
Bullous pemphigoid
Pemphigus vulgaris

Q: Bullous DDx
A: Bullous pemphigoid
Thermal burm
TENS/SJS
Friction burn
Bullous impetigo
Pemphigus vulgaris

Q: Crusting lesions DDx
A: Impetigo
Eczema
Tinea
Contact dermatitis
Insect bite

Q: Target lesion appearance?
A: Dark central blister
Paler pink raised middle ring
Bright red outer ring

Q: What is an iris lesion?
A: Early target lesion with only central dusky zone and outer red zone

Q: What are atypical target lesions?
A: Two zones
Raised in EM and flat in SJS/TENS

Q: DDx of target lesions
A: EM
TENS
SJS

Q: What is DRESS syndrome
A: Drug reaction with eosinophilia and systemic symptoms
Presents with fever, malaise, lymphadenopathy and skin rash

Q: Causes of DRESS?
A: Phenytoin
Carbamazepine
Lamotrigine
Phenobarbitone
Allopurinol
Sulfa drugs

Q: When does DRESS occur?
A: Usually 2-6 weeks after initiation of drug

Q: How do fixed drug eruptions present?
A: Solitary or multiple oval plaques in same spot on re-exposure
Often central blister
Usually on face, tongue, genitalia and acral

Q: Two types of drug-induced photosensitivity?
A: Immunological (photoallergic)
 - UV-A converts drug in skin to immunological agent causing eczema
Toxicological (phototoxic)
 - Drug absorbs UV-A leading to inflammation leading to blistering sunburn

Q: Causes of phototoxic drug reactions
A: Doxycycline, NSAID's, cipro, amiodarone, chlorpromazine

Q: Drugs associated with serum sickness
A: Cefaclor, bactrim, hydralazine, propylthiouracil

Q: Rash of serum sickness
A: Palpable purpura, petechiae, fever, arthralgias, lymphadenopathy, low complement and high ESR (vasculitis)

Q: What is erythroderma?
A: Exfoliative dermatitis covering >90% of BSA

Q: Type I hypersensitivity reactions
A: IgE mediated e.g. anaphylaxis

Q: Type II hypersensitivity reactions
A: Cytotoxic, antibody-dependent e.g. Goodpastures

Q: Type III hypersensitivity reactions
A: Immune complex. Serum sickness

Q: Type IV hypersensitivity reaction
A: Cell-mediated immunity. Contact dermatitis

Q: DDx of extremity ulcers
A: Bacterial
Mycobacterial
Neuropathic
Arterial insufficiency
venous insufficiency
PAN/Behcets
Malignant
Necrobioisis lipoidica

Q: Where does venous stasis dermatitis occur?
A: Medial distal legs and pretibia with dependent oedema and haemosiderin staining

Q: What is pyoderma gangrenosum?
A: Recurrent cutaneous necrotising ulceration of legs
Gunmetal border
Purulent base

Q: What proportion of pyoderma gangrenosum have associated systemic illness?
A: 50%. IBD, arthritis, myeloproliferative disorder

Q: What is this?
A: Pyoderma gangrenosum
 - Purulent base
 - Irregular gunmetal coloured border

Q: What is pompholyx?
A: Dyshidrosis on hands/feet with vesicular eruption on palms and soles

Q: What is this?
A: Pompholyx

Q: Treatment of pompholyx
A: Cease all causative agents
Stop all creams
Restrict soaps
Gloves when working around house
Vaseline regularly
N/saline soak for vesicles
High potency steroid BD
Antihistamines for itch

Q: How does psoriasis present?
A: Plaque over palms/soles/elbows/knees/scalp/umbilicus/gluteal cleft
Onycholysis
Nail pitting
Yellow nails

Q: Treatment of psoriasis
A: High potency steroid + vaseline
Tar solution

Q: What is this?
A: Psoriasis vulgaris

Q: WHat is this?
A: Psoriatic nail changes
 - Pits
 - Yellow discolouration
 - Onycholysis

Q: What is erythema nodosum?
A: Inflammation of subcut fat

Q: Causes of erythema nodosum?
A: 50% idiopathic
Infectious
 - Strep, campylobacter, TB
 - HSV/EBV
 - Chronic strep infection
 - Blastomycosis, Histoplasmosis, Dermatophytes
 - Leishmaniasis, Toxoplasmosis
Drugs
 - Sulfonamides
 - COCP
 - Penicillins
Sarcoidosis
IBD
Pregnancy
Leukaemia/lymphoma
Behcets

Q: Infectious causes of erythema nodosum
A: Bacterial: Chronic strep, campylobacter, Yersinia, TB, leprosy
Parasitic: Leishmaniasis, Toxoplasmosis
Fungal: Histoplasmosis, Coccidioidomycosis, Blastomycosis, dermatophyte
Viral: HSV, EBV

Q: Treatment of erythema nodosum lesions
A: Bed rest, elevation, NSAIDs
Find cause

Q: What is this?
A: Erythema nodosum

Q: What is this?
A: Dermatitis herpetiformis

Q: What is dermatitis herpetiformis
A: Vesiculopustular plaques symmetrically on extensor surfaces, back and buttocks in gluten insensitivity

Q: Differential of non-palpable purpura without thrombocytopaenia
A: Non-thrombocytopaenic
 - Trauma
 - Steroids
 - Old age
 - Uraemia
 - Von Willebrands
 - Scurvy
 - Amyloidosis

Q: Differential of non-palpable purpura with thrombocytopaenia and splenomegaly
A: Normal bone marrow
 - Portal hypertension
 - Hypersplenism
Abnormal bone marrow
 - Leukaemia/lymphoma
 - Myelodysplastic syndrome
 - Myeloproliferative

Q: DDx non-palpable purpura with thrombocytopaenia
A: ITP, HUS/TTP, HITTS, vasculitis, sepsis, DIC, cytotoxic, aplasia, alcohol, thiazides

Q: DDx of palpable purpura
A: PAN
Leukocytoclastic
HSP
Meningococcaemia
Gonococcaemia
Rickettsial
Embolic

Q: Treatment of seborrhoeic dermatitis
A: Antidandruff shampoo
Topical hydrocortisone 1% if severe

Q: Cause of tinea capitis
A: Trichophyton

Q: What is a kerion?
A: Boggy, tender, indurated plaque with superficial pustules, inflammation and hair loss

Q: Treatment of tinea capitis?
A: Oral griseofulvin

Q: What is tinea barbae?
A: Trichophyton infection of beard
Oral griseofulvn

Q: What is sycosis barbae?
A: Deep folliculitis of beard from S. aureus
Warm compresses, mupirocin ointment and oral flucloxacillin 500mg QID

Q: Treatment of head lice?
A: Permethrin 1% applied to hair, left overnight, washed out and repeated in one week

Q: What is tinea cruris?
A: Dermatophyte infection of groin folds aka jock itch

Q: How is tinea cruris spread?
A: Person-to-person (towels), cat/dog to human or fomites

Q: How does tinea cruris present?
A: Intertriginous erythema with scaly edge and penis/scrotum sparing

Q: Treatment of tinea cruris?
A: Topical Clotrimazole BD
Clean and dry
Do not share towels
Loose fitting clothing
Antifungal powder daily

Q: Characteristic finding of candidal intertrigo?
A: satellite lesions

Q: Treatment of candida intertrigo?
A: Dry and cool
Topical clotrimazole BD
Antifungal powder daily to prevent recurrence
Zinc oxide barrier cream after clotrimazole if in nappy
If balanitis - treat partner as well and treat any candidal thrush

Q: When does scabies pruritis arise?
A: 30 days after exposure

Q: Where does scabies rash arise in adults?
A: Longitudinal erythematous/brown papules on lateral feet, wrists, ankles, interdigital spaces, axillae, groin and extensor surfaces. Head and neck sparing

Q: Where does scabies rash arise in children?
A: Generalised with face, neck and scalp involvement

Q: Treatment of scabies
A: Permethrin 5% neck down (include head in children) left on for 12 hours, then wash off and repeat in 1 week
Do all family members
Wash all bed linen and clothing in hot water and sun dry or leave in plastic bags

Q: Treatment of hidradenitis suppurativa?
A: Clindamycin 1% topically BD
Chlorhex soap twice weekly
Minimise I&D
Dermatology referral

Q: What age does psoriasis most commonly arise?
A: 20's

Q: Precipitants of flares of psoriasis
A: Alcohol
Strep pharyngitis
Severe sunburn
AIDS
Stress
Beta-blockers, lithium
Steroid withdrawal
Antimalarials

Q: What is auspitz sign?
A: Removal of psoriatic plaque reveals minute bleeding points

Q: What is Koebner phenomenon?
A: Psoriatic lesions in areas of trauma

Q: Which patients are at risk of severe seborrhoeic dermatitis?
A: Parkinsons
Down's syndrome
AIDS

Q: What is pityriasis rosea?
A: Viral infection HHV 6/7
Presents with herald patch (salmon with fine scale) then generalised eruption in 1-2 weeks
Christmas tree distribution

Q: Treatment of pityriasis rosea?
A: oral antihistamines
Topical hydrocortisone 1%
Emollients
Resolves over 4-12 weeks

Q: Christmas tree distribution rash
A: Pityriasis rosea (HHV 6/7

Q: Treatment of tinea corporis
A: Topical Clotrimazole

Q: What is pityriasis versicolour
A: Pityrosporum infection (aka Malassezia furfur)
Hypo/hyperpigmented coalescesing scaly macules on torso with fine scale

Q: What is this?
A: Pityriasis rosea with herald patch

Q: What is this?
A: Pityriasis versicolor

Q: How is pityriasis versicolor treated?
A: Antidandruff shampoo

Q: Lichen planus presentation?
A: Purple polygonal papules with pruritis

Q: Where does lichen planus arise?
A: Lumbar, flexor wrists, pretibia, scalp and penis

Q: What are Wickham striae?
A: Fine, white, lacy lines that adhere to lichen planus papules

Q: What is this?
A: Lichen planus

Q: What proportion of lichen planus have mucous membrane involvement?
A: 50%

Q: How long does urticaria last?
A: Usually <6 weeks

Q: What is dermatographism?
A: Fine stroking of skin leads to wheal and flare

Q: Common triggers of urticaria
A: Penicillins
Sulfa drugs
Food allergies
Stings/bites
Infections

Q: What is PUPP
A: Pruritic urticarial papules and plaques of pregnancy

Q: When does PUPP occur?
A: Third trimester

Q: How common is PUPP?
A: 2% of all pregnancies

Q: Where do PUPP lesions arise?
A: On abdomen

Q: Treatment of PUPP
A: Topical high-potency steroid

Q: Drug causes of urticaria
A: NsAIds
Aspirin
Contrast
ACEi
Penicillins
Sulfa drugs

Q: Drugs that cause lupus-like skin reaction
A: Procainamide
Phenytoin
Hydralazine

Q: Drugs that cause fixed drug eruption
A: Tetracyclines
Sulfas
NSAIDs
Barbiturates

Q: Drugs that cause lichenoid drug reactions
A: Gold
Captopril
Beta-blockers
Thiazides
NSAIDs

Q: Bullae =
A: >1cm

Q: DDx of bullous disease
A: Bullous pemphigoid
SJS/TENS
Bullous impetigo
Severe contact dermatitis
necrotising fasciitis
Vasculitis

Q: Most common viral exanthems
A: Adenovirus
EBV/CMV
Coxsackievirus
Echovirus
HHV-6
HBV
Paramyxovirus
RSV
Rotavirus
Rubella
HIV

Q: How long do viral exanthems usually last?
A: <1 week

Q: Do viral exanthems involve palms/soles?
A: Usually spared

Q: What proportion of genital gonococal infection suffer dissemination?
A: 2%

Q: Do gonococcal rash lesions grow N. gonorrhoea from samples?
A: Yes. Gram-stain + and culture positive if de-roofed

Q: Are urethral/pharyngeal/cervical swabs positive or negative in disseminated gonococcal infection?
A: Usually negative

Q: Treatment of disseminated gonococcal
A: Ceftriaxone 1g IV daily for one week

Q: What is this?
A: Disseminated gonococcal infection

Q: What do the lesions in disseminated gonococcal infection appear like?
A: Small red papules/vesicles on extensor surfaces of wrist/palms/hands/ankles with petechial component

Q: Dermatological manifestations of meningococcaemia
A: Petechiae
Urticaria
Haemorrhagic vesicles
Maculopapular

Q: Pathognomonic rash in meningococcaemia
A: Petechiae into palpable purpura with grey necrotic centre

Q: What is this?
A: Meningococcaemia

Q: What is purpura fulminans
A: Rare severe form of vasculitis with palpable purpura, digital necrosis, MODS and DIC

Q: What is this?
A: Purpura fulminans

Q: What is pemphigus vulgaris?
A: Generalised mucocutaneous blistering disease with grave prognosis

Q: Treatment of pemphigus vulgaris
A: Admit for IV fluid resus, corticosteroid/immunosuppressive regime and treat as a burn
Differential includes SJS/TEN

Q: What is this?
A: Pemphigus vulgaris

Q: When do koplik spots arise?
A: 2-3 days into prodrome

Q: Complications of measles
A: Pneumonitis
Otitis media
Corneal ulceration
Glomerulonephritis
Sepsis

Q: How is rubella spread?
A: Throat secretions

Q: Where does rubella rash start?
A: Face

Q: What causes roseola infantum?
A: HHV 6/7

Q: What is this?
A: Roseola infantum

Q: Complication of parvovirus B19 in adults?
A: Aplastic anaemia

Q: What causes hand, foot and mouth?
A: Coxsackievirus A16 and Enterovirus 71

Q: What does HHV 6/7 cause/
A: Roseola infantum in infants
Pityriasis rosea in adults (herald patch)

Q: DDx of generalised severe skin disorders
A: Erythema multiforme
TEN
SJS
Exfoliative erythroderma
Toxic shock syndrome
Staph scalded skin syndrome
Pemphigus vulgaris

Q: What is SJS/TEN?
A: Drug-induced (or mycoplasma) acute severe necrosis and blistering with mucosal ulceration at two or more sites

Q: How does SJS differ from TEN?
A: SJS <10% body surface area
TEN >30%
SJS/TEN overlap 10-30%

Q: Is TEN/SJS more common in young or elderly?
A: Elderly as on more medications

Q: Is TEN/SJS Nikolsky sign positive?
A: Yes. Slight finger pressure causes erosion or pressure on blister leads to lateral extension

Q: causes of SJS/TEN
A: Penicillins, allopurinol, lamotrigine, valproate, NSAID's, sulfonamides and mycoplasma

Q: Management of SJS/TEN
A: Analgesia
Cease causative agent
IV resuscitation as per modified Parkland
Emollients
Burns/ICU consult
Ophthalmology and ENT review
Eye lubrication
Genital care
IDC
DVT prophylaxis

Q: How long does acute phase of SJS/TEN last?
A: 10 days

Q: Complications of SJS/TEN
A: ARDS
DIC
Scarring
Joint contractions
Bronchiolitis
Corneal scarring

Q: What is the scoring system for TENS/SJS?
A: SCORTEN

Q: SJS mortality
A: 5%

Q: TEN mortality
A: 40%

Q: How does erythema multiforme present?
A: Acute, cutaneous +- mucosal papular eruption with target lesions

Q: Where does rash of erythema multiforme usually occur?
A: Acral sites

Q: Which patients are most at risk of erythema multiforme?
A: Young men 20-40yo

Q: How do EM minor and major differ?
A: Minor has no epidermal detachment and no/mild mucous membrane involvement
EM major is a severe multisystem disease with one mucous membrane involved

Q: How does EM differ from SJS?
A: EM has target lesions
EM is infection-induced usually
SJS is drug-induced usually
SJS has atypical target macules vs. EM has target papules
SJS has more mucosal involvement

Q: Most common causes of EM?
A: Mycoplasma (may only get mucous membrane - limited EM)
HSV

Q: What is this?
A: Target lesions of EM

Q: Management of erythema multiforme
A: Find and treat cause
Topical hydrocortisone 1%
Loratadine 10mg BD
Antiseptic chlorhex mouthwash
Xylocaine viscous for oral mucous membrane
Emolients
PO prednisolone 1mg/kg/day if severe

Q: What is Sweet's syndrome?
A: Acute febrile neutrophilic dermatosis presenting with sterile painful pustules and nodules on face, neck, trunk and arms

Q: What is Sweet's syndrome associated with?
A: IBD
RA
Haematological malignancy
Pregnancy
Strep infection
Yersinia

Q: Treatment of Sweet's syndrome
A: PO prednisolone 1mg/kg/day

Q: What is this?
A: Sweet's syndrome

Q: Mortality rate of DRESS
A: 10%

Q: What is the rate of cross-reactivity among anticonvulsants for DRESS?
A: 70%

Q: Complications of DRESS syndrome
A: Hepatitis
Nephritis
Pneumonitis
Myocarditis
Thyroiditis
Encephalitis

Q: Causes of erythroderma?
A: Eczema
Psoriasis
Drugs - Sulfonamides, allopurinol, penicillins, anticonvulsants, antimalarials (same as SJS)
Cutaneous T cell lymphoma
Idiopathic

Q: Is erythroderma painful?
A: Non-tender

Q: Complications of erythroderma
A: Skin failure - infection, hypothermia, hypovolaemic shock
Distributive shock
Protein loss and oedema
DVT
Pneumonia

Q: Is staphylococcal toxic shock syndrome itchy?
A: No

Q: When does desquamation occur in staph toxic shock syndrome?
A: 5-14 days after rash

Q: How does strep toxic shock syndrome differ to staph?
A: Less common
Usually due to invasive GBS disease vs. minor staph infection
Desquamation is less common
Mortality 36% (vs. 10%)

Q: Diagnostic criteria for toxic shock syndrome?
A: Fever
Rash
Desquamation
Hypotension
3 or more systems involved

Q: Which patients are most at risk of staph scalded skin syndrome?
A: Children <5yo

Q: Typical infections leading to staph scalded skin syndrome?
A: Conjunctivitis
Umbilical
Nasopharynx

Q: Does staph scalded skin syndrome have mucosal involvement?
A: No

Q: Three phases of staph scalded skin syndrome?
A: Erythroderma with mucous membrane sparing
Exfoliative day 2
Desquamative after day 3-5
Resolved in 7-10 days

Q: What is purpura fulminans?
A: Severe acute DIC widespread purpura

Q: DDx of purpura fulminans
A: Infectious
 - Septicaemia of any cause
 - Meningococcaemia
 - Rickettsial
 - P. falciparum
 - Typhoid
 - Disseminated varicella
Non-infectious
 - Snake bite
 - TTP
 - Warfarin-induced skin necrosis

Q: Most common cause of inherited purpura fulminans?
A: Inherited protein C deficiency

Q: Most common cause of erythema multiforme?
A: Type IV hypersensitivity to HSV

Q: What is keratoderma blenorrhagica?
A: 1-2 months after Reiter syndrome get waxy vesiculo-purulent yellow/brown lesions on palmar/plantar surfaces
May spread to scrotum, scalp and trunk
C. trachomatis isolated from affected skin

Q: What is this?
A: Keratoderma blenorrhagica

Q: Palmar and plantar rash DDx
A: Erythema multiforme
Coxsackie A16
Secondary syphilis
Janeway lesions of IE
Kawasaki
Measles
Toxic shock syndrome
Reactive arthritis
Meningococcaemia
SLE

Q: What proportion of erythema multiforme is due to drugs?
A: <10%: Penicillins, sulfonamides, NSAID's, barbiturates, anticonvulsants