Derm Flashcards
Herald Patch, Christmas Tree Distribution - diagnosis?
Pityriasis Rosea
Pityriasis Rosea duration cause demography
Common self-limiting rash, usually in adolescents and young adults, with a population prevalence of 1.3%.
Lasts 1–3m with or without treatment.
Cause is unknown but may be viral – human herpes viruses 6 and 7 have been implicated. It does not, however, appear to be contagious so is likely due to reactivation.
Classic appearance of Pityriasis Rosea
The classic description is of the appearance of a larger herald patch (usually on the trunk) followed by crops of smaller circular or oval lesions following lines of cleavage (Christmas tree distribution).
However, only 40–76% patients have the herald patch.
Scaling will be present on most lesions, and may be visible at the periphery with central clearing.
The majority of lesions are on theq trunk and proximal limbs, with <10% seen distally.
What is the ABCD rule for melanoma?
A = Asymmetry. The two halves of the mole look different in shape and/or colour
B = Border. Look around the edge of the mole. Melanoma will often have an irregular, jagged, notched or blurred border
C = Colour. Several different colours or shades of colour, or a single colour that is different to other moles
D = Dimensions (changing size). Melanoma can spread outwards as a flat lesion, it can grow upwards as a hard lump and some do both.
Most common & 2nd most common cause of Erythema Multiforme?
Infections are associated with EM in up to 90% of cases – most commonly herpes simplex virus (HSV) infection. The HSV infection usually precedes the skin eruption by 3–14 days.
Mycoplasma pneumoniae is the next most common trigger.
Describe Erythema Multiforme Rash
erythema multiforme (EM). This is an acute, self-limiting and, at times, recurring skin condition thought to occur due to a hypersensitivity reaction against certain infections and medications. The rash is characterised by ‘target lesions’. These are circular lesions often with a central paler area or blister. Usually no treatment is needed and the rash fades within two weeks.
What is Herpetic Whitlow?
Paronychia is an infection of the skin and occasionally the pulp space of the finger. It is commonly caused by herpes simplex type I virus – in which case it is called a herpetic paronychia or herpetic whitlow. It is very common amongst medical and dental personnel, and children. The fingertip is reddened, swollen and acutely tender. Vesicles form which then merge to give bullae. The bullae crust over and heal over the course of about a month. Treatment is with topical antivirals (e.g. aciclovir). The lesion should not be drained due to the tendency for bacterial super-infection.
Treatment regimen for Scabies?
Treatment with 5% permethrin cream (Lyclear ®) should be given to the patient and all his/her close household contacts.
The cream is applied to the whole body from the neck downward and washed off after 8–24 hours, repeating the same procedure after seven days.
Cream should be reapplied to the hands if they are washed within eight hours of application. The itch of scabies may persist for several weeks after the infestation has cleared.
