39. Skin rash and eruptions Flashcards
History taking rash
HoPC: distribution, how the rash has changed, itch, associated symptoms
MHx: recent infections,
DHx: new medications, immunosuppressant medications, allergies
SHx: close contacts unwell? Contact with children? Travel history, Sexual history, occupation,
Examination steps rash
General inspection (number, distribution and size)
Configuration (shape/outline)
Colour and blanching
Morphology (form and structure)
Palpation
ddx erythematous rash
Staphylococcal scalded skin
Toxic shock syndrome
TEN and SJS
Erythema nodosum
Erythroderma and erythrodermic psoriasis
Acute generalised exanthematous pustulosis (AGEP)
(Still’s disease)
ddx maculopapualr rash
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Erythema multiforme
Lyme disease
Syphilis
Childhood exanthems: measles, scarlet fever, rubella, parvovirus, roseola infantum
Pityriasis rosea
Rheumatic fever
(Kawasaki disease)
ddx vesiculobullous rash
Bullous pemphigoid
Pemphigus vulgaris
Varicella
Hand-foot-and -mouth
Eczema herpeticum
Bacterial superinfection (of chickenpox or eczema)
ddx petechial/purpuric rash
Infection (palpable)
(Meningococcal meningitis)
Disseminated gonococcal infection
(Infective endocarditis)
Immune (palpable)
(Vasculitis: HSP, polyarteritis nodosa)
Bleeding (non-palpable)
(DIC and sepsis)
(Scurvy)
(ITP)
(TTP)
(Leukaemia)
acral distribution
distal areas including the hands and feet (e.g. hand, foot and mouth disease).
extensor distribution
extensor surfaces including the elbows and knees (e.g. psoriasis).
flexural distribution
flexural surfaces including the axillae, genital region and cubital fossae (e.g. eczema).
Seborrhoeic/follicular distrubution
affecting areas with increased numbers of sebaceous glands such as the face, scalp, chest and axillae (e.g. acne). eg seborrheoic dermatitis
Dermatomal distribution
he skin lesions appear confined to one or several dermatomes and do not cross the midline (e.g. herpes zoster).
discrete vs confluent lesions
Discrete lesions: individual lesions, clearly separated from one another (e.g. normal mole).
Confluent lesions: lesions that appear to be merging together (e.g. urticaria).
linear lesions
lesions in the shape of a line (e.g. excoriations).
discoid vs target vs annular lesions
Discoid lesions: coin-shaped lesions (e.g. discoid eczema, discoid lupus).
Target lesions: concentric rings of varying colour, resembling a bullseye (e.g. erythema multiforme).
Annular lesions: ring-like lesions with a central clearing (e.g. tinea corporis).
petechiae vs purpura
Petechiae - small red lesions caused when capillaries leak blood into the skin, DO NOT blanch when pressure is applied
Purpura - petechiae that are larger than 0.5cm.
macule vs patch
Macule: a flat area of altered colour less than 1.5cm in diameter.
Patch: a flat area of altered colour greater than 1.5cm in diameter.
Papule vs nodule
Papule: a solid raised palpable lesion less than 0.5cm in diameter.
Nodule: a solid raised palpable lesion greater than 0.5cm in diameter.
plaque
Plaque: a palpable flat lesion usually greater than 1cm in diameter. Most plaques are raised, however, some may be thickened without being visibly raised.
vesicle vs bulla
Vesicle: a raised, clear fluid-filled lesion less than 0.5cm in diameter.
Bulla: a raised, clear fluid-filled lesion greater than 0.5cm in diameter.
Pustule
Pustule: a pus-containing lesion less than 0.5cm in diameter.
cyst vs boil vs abscess
Cyst: A cyst is a cavity or sac that is filled with pus or fluid semisolid material or air. Cysts can be benign or malignant and can form on any part of the body. An infected cyst = abscess.
Abscess: An abscess is an infection filled with pus, is painful, and can happen anywhere on the body.
Boil: A small skin abscess is also called a boil and can appear on any body part. A boil is also known as a furuncle.
Wheal
an oedematous papule or plaque caused by dermal oedema.
(urticaria)
Lichenification
Thickening of the epidermis with exaggeration of normal skin lines, typically caused by chronic rubbing or scratching of an area (e.g. chronic eczema).
Excoriation
loss of epidermis associated with trauma