Derm Flashcards
What is pellagra?
Caused by B3 (niacin) deficiency.
What are the 3 key features of pellagra?
Dementia
Diarrhoea
Dermatitis
What are 2 key risk factors for pellagra?
1) Isoniazid therapy (isoniazid inhibits the conversion of tryptophan to niacin)
2) Alcoholism
Describe dermatitis in pellagra
Brown scaly rash on sun-exposed sites - termed Casal’s necklace if around neck
What is the most appropriate test for diagnosing allergic contact dermatitis?
Skin patch test
This involves applying a small amount of suspect allergen onto a patch, which is then placed on the patient’s skin. After 48 hours, the patch is removed and any reaction is assessed.
What is the 1st line treatment of eczema herpeticum?
IV aciclovir
What is the 1st line management of chronic plaque psoriasis?
Potent corticosteroid applied OD + vitamin D analogue (e.g. calcipotriol) OD.
For up to 4 weeks as initial treatment.
What is the treatment of choice in 2ary care management of chronic plaque psoriasis?
Phototherapy - narrowband ultraviolet B light
What is used 1st line for systemic therapy in chronic plaque psoriasis?
Oral methotrexate
Mx of scalp psoriasis?
Potent topical corticosteroids OD for 4 weeks
What type of hypersensitivity reaction is anaphylaxis?
Type I hypersensitivity
What is seborrhoeic dermatitis?
A chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a fungus called Malassezia furfur (normal skin inhabitant).
Features of seborrhoeic dermatitis?
1) Eczematous lesions on the sebum-rich areas: scalp (may cause dandruff), periorbital, auricular and nasolabial folds
2) Otitis externa
3) Blepharitis
What are 2 conditions associated with seborrhoeic dermatitis?
1) HIV
2) Parkinson’s
1st line management of scalp seborrhoeic dermatitis?
ketoconazole 2% shampoo
What are 2 common complications of seborrhoeic dermatitis?
Blepharitis & otitis externa
What is lichen planus?
A skin disorder of unknown aetiology.
Presentation 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).
Oral involvement common.
What medications are known to exacerbate psoriasis?
1) beta blockers
2) lithium
3) antimalarials (chloroquine and hydroxychloroquine)
4) NSAIDs
5) ACEi
6) infliximab
What are some factors that can exacerbate psoriasis?
1) trauma
2) alcohol
3) drugs: beta blockers, lithium, antimalarials (chloroquine and hydroxychloroquine), NSAIDs and ACE inhibitors, infliximab
4) withdrawal of systemic steroids
What infection may trigger guttate psoriasis?
Strep. infection
What malignancies can acanthosis nigricans be associated with?
GI malignancies e.g. gastric & pancreatic cancer
Mx of guttate psoriasis?
Emollients and reassurance.
Most cases of guttate psoriasis resolve spontaneously within 2-3 months and emollients can help with managing dry skin, scaling, and itch.
What is the most common cause of nappy rash in infants?
Irritant dermatitis
How can spider naevi be differentiated from telangiectasia?
By pressing on them and watching them fill.
Spider naevi fill from the centre, telangiectasia from the edge.
What can pityriasis rosea initially present with?
A herald patch (usually on the trunk).
What is Auspitz’s sign:?
In plaque psoriasis, if the scale is removed, a red membrane with pinpoint bleeding points may be seen.
What is dermatitis herpetiformis?
Dermatitis herpetiformis is an autoimmune blistering skin disorder associated with coeliac disease.
It is caused by deposition of IgA in the dermis.
Features of dermatitis herpetiformis?
itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks)
How is a diagnosis of dermatitis herpetiformis made?
Skin biopsy –> deposition of IgA in a granular pattern in the upper dermis
What is guttate psoriasis often triggered by?
Preceding streptococcal infection such as tonsillitis.
What is pompholyx eczema?
A type of eczema which affects both the hands and the feet.
What is pompholyx eczema often precipitated by?
Humidity e.g. sweating
High temperatures
How many treatments do patients with scabies require?
2 –> applications one week apart
What typically precedes the rash in chickenpox?
Fever
What is the Koebner phenomenon?
Describes skin lesions that appear at the site of injury.
What is hand, foot & mouth disease?
A self-limiting condition affecting children.
It is caused by the intestinal viruses of the Picornaviridae family (most commonly coxsackie A16 and enterovirus 71).
It is very contagious and typically occurs in outbreaks at nursery.
Clinical features of hand, foot and mouth disease?
1) mild systemic upset: sore throat, fever
2) oral ulcers
3) followed later by vesicles on the palms and soles of the feet
Mx of hand, foot and mouth disease?
symptomatic treatment only: general advice about hydration and analgesia
Which condition has a ‘strawberry tongue’ and ‘sandpaper’ rash?
Scarlet fever
What is hand, foot and mouth disease most commonly caused by?
Coxsackie A16 and enterovirus
