7: Dermatitis / atopic eczema Flashcards
What is another name for dermatitis?
Eczema
What is another name for eczema?
Dermatitis
What is papillomatosis?
Irregular epithelial thickening
What is the characteristic histological feature of eczema?
Spongiosis (oedema between keratinocytes)
Which immune cells infiltrate the epidermis in eczema?
Neutrophils
Lymphocytes
What is the common symptom for all types of eczema?
Pruritus (itching)
What are the two phases of an eczema reaction?
Acute phase
Chronic phase
What happens in the acute phase of an eczema reaction?
Rapid acute inflammation
What does eczema look like in the acute phase?
Papulovesicular
Erythematous
Spongiotic
Oozing / scaly / crusty
What does eczema look like in the chronic phase?
Thickened (lichenification)
Elevated patches –> PLAQUES
Even scalier
What are the four defining morphological features of eczema?
Itchy
Ill-defined
Erythematous
Scaly
What type of eczema is brought about by a Type IV hypersensitivity reaction?
Contact allergic eczema
What type of eczema reaction is brought about by substances which aren’t allergens?
Contact irritant eczema
Give two examples of substances which cause contact irritant eczema.
Soap
Water
Urine
Faeces
What is atopic eczema?
Inflammation of the skin due to genetic and environmental factors versus allergens or irritants
Which types of hypersensitivity reactions occur in drug-related eczema?
Type I
Type IV
Which immune cells are seen in drug-related eczema?
Eosinophils
What is the histological feature common to ALL types of eczema?
Spongiosis (oedema between keratinocytes)
If a patient has eczema on sun-exposed areas only, which type of eczema may they have?
Photosensitive eczema
What is lichen simplex eczema?
Inflammation due to scratching
What is stasis dermatitis?
Skin inflammation due to hydrostatic pressure in legs with poor circulation (see also: varicose veins)
Which cells leak into the extracellular compartment and cause inflammation in stasis dermatitis?
Why?
Red blood cells
Increase in capillary hydrostatic pressure (in turn due to decreased venous circulation, e.g heart failure or peripheral vascular disease)
Give some examples of allergens which cause contact allergic dermatitis.
Chemicals
Drugs (e.g penicillin)
Nickel!!!!
Where is nickel commonly found which can cause contact allergic dermatitis?
Belt buckles, buttons
Why do people tend to get worse contact allergic reactions on the dorsal surfaces of their hands?
The skin is thinner
Which substance, increasingly found in the air, can cause contact allergic reactions on the face?
Perfume
What is typically seen in the acute phase of eczema?
Weeping blisters (due to rapid severe spongiosis)
Which cells, found in the epidermis, bind to antigens on the skin?
Langerhans cells
Where do Langerhans cells take antigens for transport to T cells?
Lymphatic vessels
Which cells do Langerhans cells present antigen to?
T cells
Which immune cells are responsible for spongiosis in the epidermis upon contact with an allergen?
Lymphocytes
Which cells trigger dermatitis?
Lymphocytes
What are the two main histological features of contact allergic eczema?
Lymphocyte infiltration
Spongiosis
Which investigation allows you to figure out which allergens a patient is allergic to?
Patch testing
If the patient is allergic to one of the substances in a patch test, what will be seen in that battery 96 hours later?
Contact allergic eczema
Irritant contact eczema is a (specific / non-specific) reaction to a substance.
non-specific
Why do people wearing rings develop dermatitis even though they aren’t allergic to the metal in them?
Soap is trapped under the ring during hand washing
Name five clinical features of severe hand dermatitis.
Oedema
Erosions
Lichenification
Fissures
Scales
Nail dystrophy
What kind of eczema is “nappy rash”?
Contact irritant eczema
Why may a patient have irritant dermatitis around their lips?
They’ve been licking them i.e saliva
Which kind of eczema is associated with asthma and hayfever?
Atopic eczema
What is the main symptom of atopic eczema in children?
Pruritus
What is a major quality of life impact of pruritus?
Sleep disturbance > Fatigue > Poor school/work/life performance
Apart from itching, what are other signs and symptoms of atopic eczema?
Ill-defined erythema
Scales
Dry skin
On which surfaces is atopic eczema seen?
Flexural surfaces
Apart from flexural surfaces, where else is atopic eczema found?
Face
Groin
Bit below ear
If a child has a patch of dermatitis below the fold in their ear, what do they probably have?
Atopic eczema
What are skin changes seen in chronic atopic eczema?
Lichenification
Excorciation (erosion caused by scratching)
Secondary infection
What commensal bacteria are seen in far greater numbers in people with atopic eczema, and may contribute to secondary infection?
Staph. aureus
Staph. epidermidis
What does crusting (golden/yellow) indicate in a patient with atopic eczema?
Staph. aureus
What infection does eczema herpeticum (rash on the buttocks) indicate?
Herpes simplex
How would you describe eczema herpeticum?
Monomorphic punched-out lesions
How should eczema herpeticum be treated?
Oral acyclovir
Is eczema herpeticum a one-off infection?
No, tends to recur
What should be used to address dryness in patients with eczema?
Emollients
Which products should be avoided in patients with eczema?
Irritants - e.g shampoos and soaps
If emollients and antigen/irritant avoidance don’t work, how can you treat eczema?
Topical steroids
Phototherapy (UVB)
Immunosuppression
When should topical steroid be stopped?
When the eczema dies down
What are biologic agents?
Monoclonal antibodies used to treat skin conditions (e.g psoriasis, eczema)
The gene for which protein is important in the genetic cause of atopic eczema?
Filaggrin
Round, scaly, WELL-DEFINED eczema found on the extensor aspects of the arms is…
Discoid eczema
What is the difference between discoid eczema and psoriasis?
Discoid eczema produces PATCHES
Psoriasis produces PLAQUES
A patient has a cut-off of their eczema at the collar line. What type of eczema do they have?
Photosensitive eczema
What can trigger photosensitive eczema in a patient who isn’t normally photosensitive?
Drugs
What are some examples of drugs which cause photosensitivity in some patients?
Antibiotics (tetracyclines)
NSAIDs (ibuprofen)
Diuretics
Retinoids
What type of eczema is found around swollen varicose veins?
Stasis eczema
What is another name for cradle cap?
Seborrhoeic dermatitis
What is the name for a sub-type of eczema where the oedema can’t escape and instead forms itchy vesicles on the palms and fingers?
Pompholyx
What is the pathomechanism of lichen simplex eczema?
Scratching
