Dermatology Flashcards
What is the alternative name for ring worm?
Tinea Corporis
What is the cause of ringworm?
Dermatophyte infection - microsporum Canis
What is the cause of tinea capitus?
Fungal scalp infection - caused by trichophyton
How does ring worm tend to present?
Annular, erythematous scaly lesion - pruritic border and clear centre - typically presents on the arm s
Which toxins are associated with staphylococcal scalded skin?
Epidermolytic toxins A&B
Known as exfoliative toxins which disrupt the layer between the stratum spinosum and the stratum granulosa
Which toxin is commonly implicated in food poisoning causing gastroenteritis?
Staphylococcal enterotoxin A
What is lichenification?
Thickening of the epidermis with exaggerated skin markings
Seen in eczema
What is dermographism?
The phenomenon of scratching which causes the formation of erythematous wheals within the dermis of the skin
Seen in urticaria
What is acanthosis?
Thickening of the skin with marked proliferation of keratinocytes in the epidermis
Seen in psoriasis
What is Kobner Phenomenon?
The formation of skin lesions at sites of trauma or scarring
Seen occasionally in psoriasis
What is parakeratosis?
The retention of nuclei in the stratum corneum due to keratinocytes maturing and proliferating so rapidly
Specific to psoriasis
Keloid scarring is over activity of which cell type?
Fibroblasts
What is the site of the blisters in pemphigoid?
Subepidermal
Hence tense robust blisters
What is the site of the blisters in pemphigus?
Intra-epidermal
Hence flaccid and easily broken blisters
What is the pathophysiology of pemphigus?
Results from autoantibodies against desmogleins
Which conditions are associated with Steven Johnson Syndrome?
Herpes Simplex Virus
Mycoplasma pneumoniae infection
HIV
Being immunocompromised
Previous Hx of SJS
Drug sensitivities (e.g. penicillins, phenytoin, COCP)
What virus causes Roseola Infantum?
HHV 6 - most commonly
Can also be caused by adenovirus and enterovirus
What are the features of roseola infantum?
Classically high fever
Followed by a blanching, maculopapular rash which occurs once the fever subsides
Which virus is associated with a rash formation when treated with amoxicillin?
EBV
Describe the pathophysiology of vitiligo?
Autoimmune aetiology affecting melanocytes (melanocytes reside in the epidermis)
Describe the histopathological appearance in alopecia areata?
Characterised by T cells within the peribulbar infiltrate that release cytokines and chemokine
What are the features of Sturge Weber Syndrome?
Port wine stain (naevus flammus) in the ophthalmic or maxillary divisions of the trigeminal nerve with a capillary vascular malformation intracranially
Can give rise to seizures
May also have hemisensory disturbance, hemiplegia, contralateral hemianopia and developmental delay
Head XR would show tramline calcifications
Which enzyme is affected in Sjogren-Larsson syndrome?
Deficiency in the enzyme fatty aldehyde dehydrogenase
What does TSC1 and TSC2 encode?
TSC1 encodes the protein hamartin
TSC2 encodes the protein tuberin
Both are implicated in tuberous sclerosis
