Dermatology Flashcards
(24 cards)
At what age of gestation does the fetal skin become impermeable?
19 weeks
When does the epidermis gain full barrier function?
A few weeks after birth
Where are melanocytes derived from and where do they migrate to?
Derived from the ectoderm and migrate from the neural tube to the epidermis
What is epidermal naevus?
Overgrowth of epidermal keratinocytes and mutations are associated with epideral naevus present only in the cells of the naevus and not the normal skin surrounding. Presents with linear warty streaks
What protects against shearing forces of the skin?
Dermal epidermal junction
What are strawberry birthmakrs (infantile hemagioma)?
proliferation of endothelial cells and mutations in genes that encode for vasculat endothelial growth factor
How are strawberry hemangiomas treated?
No intervention because they do tend to spontaneously resolve over years.Steroids and oral propranalol are effective
What is the most common vasculitis in childhood?
Henloch schonlein purpura usually preceded by a URTI. Spontaneous resolution in 4 weeks - symptomtatic treatment
When can renal manifestations of HSP present?
Usually 6 months following skin manifestations
What is morphoea?
Localised scleroderma. Initial oedema, fibrosis of the skin and atrophy which can also extend to the muscle and bone. Aetiology is still not understood well
What is the most common subtypre of morphoea?
Linear morphoea usually just one limb is affected
What causes erythema nodosum and which layer of the skin is affected?
Paniculitis (subcutaneous fat tissue develops nodules) Delayed hypersensitivity reaction to various triggers such as TB, parvovirus, EBV, malignancy, Hodgkins lymphoma, LCH
What is thought to be the main mechanism for vitiligo?
Autoimmune lymphocytic attack on melanocytes. Immune modulating treatments such as topical calcineurin inhibitors tracrolimus
What are potential side effects to topical steroids?
Skin infections, thinning, glaucoma and cataracts
What is the most common trigger for erythema multiforme?
Herpres simplex virus
What are the two subtypes of albinisim?
Oculocutaneous (OCA) and ocular albinism
What are the differences between OCA1(A) subtype vs OCA1(B) and OCA2?
OCA1A- white hair, blue-grey eyes, milky white skin. impaired vision ABSENCE of tyrosinase enzyme
OCA1B- some pigmentation of the hair and skin with age. REDUCTION of tyrosinase enzyme
OCA2- normal tyronise activity but lack of functional P proteins. variable pigmentary dilution of hair, skin and iris
Name some conditions associated with cafe au lait macules
Cafe au lait patches- increase in melanin in melanocytes and basal keratinocytes. Tuberous sclerosis, neurofirbomatosis, Mccun ealbright syndrome, fanconi anaemia
Name an enzyme that plays a critical role for melanogenesis
Tyrosinase, P protein is involved in the regulation of the PH within melanosomes
How is pediculosis (head lice/nits) diagnosed and treated?
Clinical diagnosis - you can visualise the eggs on the proximal shaft of the hairs. Tx- lindane, malathion, pyrethrin, pyrethroid
Which gene is large plaque psoriasis associated with?
HLA-Cw6
What are nail changes associated with psoriasis?
Pitting oncholysis and subungal hyperkeratosis
What is bloom syndrome?
Autosomal recessive condition characterised by growth retardation, photosensitiivty, predisposition to cancers such as leukemia/lymphoma, pigment abnormalities and telangtesia
How long does scabies mite take to cause symptoms and how is it diagnosed?
Skin scrapes and usually takes 1 month for symptoms, Tx-permithrim and in severe cases ivermectin
