Dermatology Flashcards
What is Erythema Multiforme?
A hypersensitivity reaction that is most commonly triggered by infections. It may be divided into minor and major forms. Erythema multiforme major is associated with mucosal involvement.
In patients with psoriasis, how long should they take a break from courses of topical corticosteroids?
4 week
What are the features of Lichen planus?
- 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)
- Koebner phenomenon may be seen (new skin lesions appearing at the site of trauma)
- oral involvement in around 50% of patients: typically a white-lace pattern on the buccal mucosa
- nails: thinning of nail plate, longitudinal ridging
Features of pyoderma gangrenosum?
location: typically on the lower limb, often at the site of a minor injury as in this patient’s case and this is known as pathergy
initially features: usually starts quite suddenly, small pustule, red bump or blood-blister
later features: the skin then breaks down resulting in an ulcer which is often painful, the edge of the ulcer is often described as purple, violaceous and undermined.
the ulcer itself may be deep and necrotic
may be accompanied by systemic symptoms: fever, myalgia
What areas are involved in Wallace’s Rule of Nine?
Each of the following is 9% of the body when calculating surface area % if a burn: Head + neck each arm each anterior part of leg each posterior part of leg anterior chest posterior chest anterior abdomen posterior abdomen
Management of Lichen Planus
- potent topical steroids are the mainstay of treatment
- benzydamine mouthwash or spray is recommended for oral lichen planus
- extensive lichen planus may require oral steroids or immunosuppression
How long does the pityriasis rosea rash last?
6-12 weeks
What is recommended antiviral use in shingles?
in practice, they recommend antivirals within 72 hours for the majority of patients, unless the patient is < 50 years and has a ‘mild’ truncal rash
associated with mild pain and no underlying risk factors
one of the benefits of prescribing antivirals is a reduced incidence of post-herpetic neuralgia, particularly in older people
aciclovir, famciclovir, or valaciclovir are recommended
Classic symptoms of Seborrhoeic dermatitis
dandruff and eczematous lesions with flakes on the periorbital, auricular and nasolabial folds
otitis externa and blepharitis may develop
What is the step-up management of acne?
1) single topical therapy (topical retinoids, benzoyl peroxide)
2) topical combinatiom therapy (topical antibiotic, benzoyl peroxide, topical retinoid)
3) oral antibiotics (tetracyclines, erythromycin in pregnancy) used for max. of three months. Topical retinoid or benzoyl peroxide should always be co-prescribed to reduce riso fo antibiotic resistance developing. Topical and oral antibiotics should not be used in combination. Gram-negative folliculitis may occur as complication of long-term antibiotic use (high dose oral trimethoprim is effective is this occurs)
4) COCP - alternative to oral antibiotics, should be used in combination with topical agents. Dianette sometimes used due to anti-androgen properties, however high risk of VTE so only given 3 months and women counselled about risks
5) oral isotretinoin - only under specialist supervision. Pregnancy is contraindication.
What is Pityriasis versicolor?
Is a superficial cutaneous fungal infection caused by Malassezia furfur which usually presents on the trunk or back and is scaly is appearance.
Inpatient treatment for erythroderma must be monitored for what complications?
Dehydration, infection and high-output heart failure
What is erythema nodosum?
inflammation of subcutaneous fat
typically causes tender, erythematous, nodular lesions
usually occurs over shins, may also occur elsewhere (e.g. forearms, thighs)
usually resolves within 6 weeks
lesions heal without scarring
What are causes of erythema nodosum?
infection (streptococci, tuberculosis, brucellosis)
systemic disease (sarcoidosis, inflammatory bowel disease, Behcet’s)
malignancy/lymphoma
drugs (penicillins, sulphonamides, combined oral contraceptive pill)
pregnancy
What is Pityriasis versicolour?
Pityriasis versicolor, also called tinea versicolor, is a superficial cutaneous fungal infection caused by Malassezia furfur (formerly termed Pityrosporum ovale)
Features: most commonly affects trunk patches may be hypopigmented, pink or brown (hence versicolor). May be more noticeable following a suntan scale is common mild pruritus
What triggers worsen psoriasis?
alcohol, smoking, stress, discontinuing steroids or initiating NSAIDs, lithium, antimalarials and beta-blockers
Morphoeic BCC v Nodular BCC
associated more extensive spread than nodular BCC as it is more aggressive and often presents later
Gold-standard treatment of Morphoeic BCC
Mohs microgaphic surgery
involves microscopic examination of excised tissue during the surgery. This is useful in tumours with poorly-defined edges to ensure that the whole tumour has been excised while minimising removal of healthy tissue.
What is Erythema ab igne?
a skin disorder caused by over exposure to infrared radiation. Characteristic features include reticulated, erythematous patches with hyperpigmentation and telangiectasia. A typical history would be an elderly women who always sits next to an open fire.
If the cause is not treated then patients may go on to develop squamous cell skin cancer.
What is toxic epidermal necrolysis?
is a potentially life-threatening skin disorder that is most commonly seen secondary to a drug reaction. In this condition, the skin develops a scalded appearance over an extensive area.
What drugs can cause toxic epidermal necrolysis?
phenytoin sulphonamides allopurinol penicillins carbamazepine NSAIDs
Risk factors of SCC?
- excessive exposure to sunlight / psoralen UVA therapy
- actinic keratoses and Bowen’s disease
- immunosuppression e.g. following renal transplant, HIV
smoking - long-standing leg ulcers (Marjolin’s ulcer)
- genetic conditions e.g. xeroderma pigmentosum, oculocutaneous albinism
Features of BCC?
many types of BCC are described. The most common type is nodular BCC, which is described here
sun-exposed sites, especially the head and neck account for the majority of lesions
initially a pearly, flesh-coloured papule with telangiectasia
may later ulcerate leaving a central ‘crater’
Features of Hidradenitis suppurativa?
chronic, painful, inflammatory skin disorder. It is characterized by the development of inflammatory nodules, pustules, sinus tracts, and scars in intertriginous areas. It should be suspected in pubertal or post-pubertal patients who have a diagnosis of recurrent furuncles or boils, especially in intertriginous areas.
Rosacea Treatment?
mild/moderate: topical metronidazole
severe/resistant: oral tetracycline
First-line for hyperhidrosis?
Topical aluminium chloride
What is features of Pemphigoid gestationis?
- pruritic blistering lesions
- often develop in peri-umbilical region, later spreading to the trunk, back, buttocks and arms
- usually presents 2nd or 3rd trimester and is rarely seen in the first pregnancy
oral corticosteroids are usually required
Where do Acral lentiginous melanomas arise from?
arise in areas not associated with sun exposure e.g. soles of feet and palms
Acne patients with scarring should be referred for?
Oral isotretinoin
Common sites of keloid scars?
common sites (in order of decreasing frequency): sternum, shoulder, neck, face, extensor surface of limbs, trunk
Features of Rosacea?
nose, cheeks and forehead
flushing, erythema, telangiectasia → papules and pustules
Management of Dermatitis herpetiformis?
gluten-free diet
dapsone
What bacteria contributes to the development of acne?
Propionibacterium acnes
What is nodular melanoma?
Red or black lump, oozes or bleeds, sun-exposed skin
What formula is used to calculate the volume of fluid required for resuscitation over the first 24 hours after the burn?
Parkland formula is used to calculate the volume of IV fluid required for resuscitation over the first 24 hours after the burn
What size do you US a lipoma?
> 5cm
What is alopecia areata?
presumed autoimmune condition causing localised, well demarcated patches of hair loss. At the edge of the hair loss, there may be small, broken ‘exclamation mark’ hairs
First-line treatment for hyperhidrosis?
Aluminium chloride
What are common complications of seborrhoeic dermatitis?
Otitis externa and blepharitis
What skin disorders are seen in SLE?
Skin manifestations of systemic lupus erythematosus (SLE):
- photosensitive ‘butterfly’ rash
- discoid lupus
- alopecia
- livedo reticularis: net-like rash
What skin manifestation is seen in Reiter’s syndrome
Keratoderma blenorrhagica - describes waxy yellow papules on the palms and soles
What medication is known to exacerbate plaque psoriasis?
Beta-blockers
