Dermatology Flashcards
Most common cause of Erythema multiforme?
HSV
Causes of Erythema multiforme
viruses: herpes simplex virus (the most common cause), Orf*
idiopathic
bacteria: Mycoplasma, Streptococcus
drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine
connective tissue disease e.g. Systemic lupus erythematosus
sarcoidosis
malignancy
Dermatitis in acral, peri-orificial and perianal distribution
hypogonadotropic hypogonadism
Diagnosis?
Zinc deficiency
A non-healing painless ulcer associated with a chronic scar is indicative of ……
SCC
Multiple papules and large pustules on and around his nose, and the nose itself is enlarged and erythematous with multiple telangiectasia
Diagnosis? mx?
Rosacea
Mild-moderate: Topical ivermectin (or topical metronidazole / topical azelaic acid)
Mod-severe: Topical ivermectin + oral doxycyline
What are some common complications of seborrhoeic dermatitis?
Otitis externa and blepharitis
1st line mx of hyperhidrosis?
Topical aluminium chloride
What is dermatitis herpetiformis caused by? who is more likley for this?
deposition of IgA in the dermis
90% of cases show some gluten insensitivity
Who is most likely to get keloid scars?
More common in young, black, male adults
What is the pathophysiology of acanthosis nigricans?
insulin resistance → hyperinsulinemia → stimulation of keratinocytes and dermal fibroblast proliferation via interaction with insulin-like growth factor receptor-1 (IGFR1)
Most common malignancies associated with acanthosis nigricans?
GI ca - most commonly gastric adenocarcinoma
Mx of flexural, face or genital psoriasis?
Topical steroids
itchy, papular rash most common on the palms, soles, genitalia and flexor surfaces of arms
rash often polygonal in shape, with a ‘white-lines’ pattern on the surface (Wickham’s striae)
Diagnosis?
Mx?
Dx - Lichen sclerosus
Mx - topical steroids
(if in mouth benzydamine mouthwash / spray)
Which ca is most common malignancy secondary to immunosupression?
Skin cancer - particularly SCC
Blisters / bullae:
No mucosal involvement - dx?
Mucosal involvement - dx?
no mucosal involvement (in exams at least*): bullous pemphigoid
mucosal involvement: pemphigus vulgaris
Mx of pityriasis versicolor?
Topical ketoconazole
Mx of facial hirsuitism? when not to?
Topical eflornithin
CI in pregnancy / breast feeding
small blisters on the palms and soles
pruritic
often intensely itchy
sometimes burning sensation
once blisters burst skin may become dry and crack
Worse in humidity and high temps
Dx?
Dx - pompholyx eczema
Extensive umbilicated lesions in HIV
dx?
Molluscum contagiosum
Prognosis in malignant melanoma?
Invasion depth of tumour (Breslow depth is single most important factor)
> 4mm 50% 5 yr survival
<0.75 95-100% 5 yr survival
A history of a non-healing ulcer at the site of a burn injury
diagnosis?
SCC
What are the features of systemic mastocytosis?
Systemic mastocytosis results from a neoplastic proliferation of mast cells
Features
urticaria pigmentosa - produces a wheal on rubbing (Darier’s sign)
flushing
abdominal pain
monocytosis on the blood film
How is systemic mastocytosis diagnosed?
Diagnosis
raised serum tryptase levels
urinary histamine
Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu) syndrome inheritance?
Autosomally dominant
What is the cause of porphyria cutanea tarda?
inherited defect in uroporphyrinogen decarboxylase
Triad of niacin deficiency?
Dementia + Depression
Diarrhoea
Dermatitis
What can percipitate lithium toxicity?
dehydration
renal failure
drugs: diuretics (especially thiazides), ACE inhibitors/angiotensin II receptor blockers, NSAIDs and metronidazole.
Mx of oculogyric crisis?
intravenous antimuscarinic: benztropine or procyclidine
can also use diphenhydramine
What are patients recieving CHOP for non-Hodgkins lymphoma at increased risk of? how can this risk be reduced?
Tumour lysis syndrome and associated gout secondary to hyperuricaemia
Reduce this risk by co-prescribing allopurinol
Which people are more likely to develop isoniazid toxicity?
Slow acetylators
Which drugs are affected by acetylator status?
H DIPS
hydralazine
dapsone
isoniazid
procainamide
sulfasalazine
An itchy rash affecting the face and scalp distribution is typical of …
Seborrhoeic dermatitis - malassezia furfur
associated w HIV and PD
What are some common complications of seborrhoeic dermatitis?
Blepharitis and otitis externa
What deficiency is pellagra?
B3 - Niacin (Nicotinic acid)
How to mx face, flexural or genital psoriasis?
Mild / moderate corticosteroid topically OD / BD for max 2 weeks
Which skin disorder is associated with Graves? What does this look like?
Pretibial myxoedema - symmetrical, erythematous skin with shiny, orange peel appearance
Pityriasis rosea causative organism?
Herpes hominis virus 7
HHV 7
A non-healing painless ulcer associated with a chronic scar
is suggestive of?
SCC
shiny, atrophic, yellow-brown plaques on the shins with telangiectasia and occasional ulceration on shins are suggestive of?
Necrobiosis lipoidica diabeticorum
associated with diabetes
Possible causes of acanthosis nigricans?
acanthosis nigricans is associated with all the things that are associated with weight gain: hypothyroid, DM, acromegaly, prader willi, PCOS, COCP, obesity.
And then just gotta remember gastric ca on top
Causes of hypertrichosis?
drugs: minoxidil, ciclosporin, diazoxide
congenital hypertrichosis lanuginosa, congenital hypertrichosis terminalis
porphyria cutanea tarda
anorexia nervosa
Mx of roseaca?
Simple - sunscreen + camouflage creams
predominant flushing
> topical brimonidine gel (topical a-adrenergic agonist)
mild-moderate papules / pustules
> topical ivermectin (or metro / azelaic acid)
moderate-severe papules / pustules
> combination of topical ivermectin + oral doxy
Which ca is Acquired ichthyosis associated with?
Lymphoma
Acquired hypertrichosis lanuginosa is associated with which ca?
GI and Lung ca
Dermatomyositis is associated with which ca?
Ovarian + lung ca
Erythema gyratum repens is associated with which ca?
Lung
Erythroderma is associated with which ca?
Lymphoma
Migratory thrombophlebitis is associated with which ca?
Pancreatic ca
Necrolytic migratory erythema is associated with which ca?
Glucagonoma
Pyoderma gangrenosum (bullous and non-bullous forms) is associated with which ca?
Myeloproliferative
Sweet’s syndrome is associated with which ca?
Haematological malignancy e.g. Myelodysplasia - tender, purple plaques
Tylosis is associated with which ca?
Oesophageal cancer
Pyoderma gangrenosum mx?
Oral steroids - due to risk of progression rapidly
Immunosuppressants ciclosporin + infliximab may be involved in difficult cases
Stop any surgery plans until disease is controlled to risk worsening (pathergy)
Adverse effects associated with retinoid use?
Teratogenicity
Dry skin, eyes, lips / mouth - most common (also nose bleeds due to drying of nasal mucosa)
low mood
raised triglycerides
hair thinning
Intracranial HTN - dont combine w tetracyclines
Photosensitivity
Describe where keloid scars are most likely to form?
common sites (in order of decreasing frequency): sternum, shoulder, neck, face, extensor surface of limbs, trunk
What can exacerbate psoriasis?
trauma
alcohol
drugs: beta blockers, lithium, antimalarials (chloroquine and hydroxychloroquine), NSAIDs and ACE inhibitors, infliximab
withdrawal of systemic steroids
What is systemic mastocytosis and what are the features?
Systemic mastocytosis results from a neoplastic proliferation of mast cells
urticaria pigmentosa - produces a wheal on rubbing (Darier’s sign)
flushing
abdominal pain
monocytosis on the blood film
How is systemic mastocytosis diagnosed?
Raised serum tryptase
Urinary histamine
MoA of pemphigus vulgaris? what are the features of this disease?
Desmoglein 3 antibodies -> mucosal ulceration, skin blistering + acantholysis on biopsy?
Linear, well-demarcated skin lesions that appear suddenly, with ‘la belle indifference’ →
dermatitis artefacta
What is melasma, how does it present?
Melasma, also known as chloasma or ‘mask of pregnancy’
presents as symmetrical hyperpigmented patches typically affecting the face, particularly the cheeks, forehead, upper lip, and nose
Caused by increased oestrogen + progesterone -> stimulation of melanocytes esp during 2nd-3rd trimester
Adverse effects of (psoralen + ultraviolet A light) PUVA therapy?
adverse effects: skin ageing, squamous cell cancer (not melanoma)
Mx of keloid scars?
early keloids may be treated with intra-lesional steroids e.g. triamcinolone
What are the features of vitiligo?
well-demarcated patches of depigmented skin
the peripheries tend to be most affected
trauma may precipitate new lesions (Koebner phenomenon)
Associated w AI conditions: T1DM, Addisons, AI thyroid disorders, pernicious anaemia, alopaecia areta
What is telogen effluvium?
temporary hair shedding often related to stress, illness or medication use.
results from a larger number of hairs than normal entering into ‘telogen’ phase - a resting stage in the natural life cycle of a hair follicle - leading to increased daily shedding and diffuse thinning across the whole scalp
itchy white spots suggestive of ? where does it occur
Lichen sclerosus - typically vulval but can affect buttocks, thighs and other areas
in men affects glans penis - called balantitis xerotica obliterans
What often precedes guttate psoriasis?
Strep sore throat 2-4 weeks prior
indurated ulcerating lower lip lesion with an outdoor occupation with significant sun exposure (tour guide) and smoking history
most likely?
Lower lip malignancy most likley SCC
Eczema herpeticum organism?
primary infection of the skin caused by herpes simplex virus (HSV) and uncommonly coxsackievirus
Livedo reticularis causes?
A mnemonic I used for the causes of LR is PACE-ISH
- Polyarteritis nodosa
- Antiphospholipid syndrome
- Cryoglobilinaemia
- Ehler-Danlos
- Idiopathic (Most common)
- SLE
- Homocystinuria
Pigmentation of nail bed affecting proximal nail fold suggests ???
Acral lentiginous melanoma - sign described is hutchingsons sign
typically affecting 40+ typically seen in darker skin tones
What is erythema ab igne caused by and look like? Complication?
Erythema ab igne is caused by overexposure to infrared radiation - reticulated, erythematous patches with hyperpigmentation and telangiectasia
If cause not stopped can lead to SCC
Mx of lichen planus?
Potent topical steroids
Benzydamin mouthwash for oral lichen planus
Extensive - oral steroids / immunosuppression
Porphyria cutanea tarda is caused by
nherited defect in uroporphyrinogen decarboxylase
blistering rash on the face and dorsal hands provoked by sunlight and alcohol
+ hypertrichosis is suggestive of?
Porphyria cutanea tarda
Most common cause of isotretinoin?
Dry skin
TPN can lead to what deficiency? derm finding?
Zinc deficiency can lead to acrodermatitis herpetiformis -> peri-orificial dermatitis and alopecia.
Acute onset of tear-drop scaly papules on trunk and limbs
+- preceeding strep infection
dx?
Guttate psoriasis
Most common cause of ca in upper lip?
BCC
dermatitis herpetiformis - diagnosis?
Skin biopsy
keratin pearls seen in whcih skin ca?
SCC
Acne with scarring - what to provide?
Oral isotretinoin
slow-growing, flesh-coloured or pink lesions with a pearly appearance. The rolled edges, central depression and presence of telangiectasia (dilated blood vessels) are classic features
Suggestive of what>
BCC - most common skin cancer in UK occurring on sun exposed regions
first-line treatment for pyoderma gangrenosum?
Oral steroids
