Key Skin Conditions Flashcards
What is erythema nodosum and where is it usually seen?
it is a type of panniculitis - an inflammatory disorder affecting subcutaneous fat
it presents as tender red nodules on the anterior shin
What is the treatment for erythema nodosum?
What age group tends to be affected?
it typically resolves spontaneously within 30 days
it is common in young people aged 12-20
What causes erythema nodosum?
It can be caused by a wide variety of conditions and is often described as an external manifestation of internal conditions
it is thought to be a delayed hypersensitivity reaction to a variety of antigens
What is the SORE SHINS mnemonic for the causes of erythema nodosum?
S - streptococci
O - oral contraceptive pill
R - rickettsia
E - eponymous (Behcet disease)
S - sulfonamides
H - hansen’s disease (leprosy)
I - inflammatory bowel disease
N - non-hodgkin lymphoma
S - sarcoidosis
If someone presents with a rash on both legs, why would you think it is unlikely to be infection?
The infection has to enter the leg through an opening in order to cause cellulitis
It is unlikely that the infection has entered both legs simultaenously
Infection is rarely seen bilaterally, but is occasionally seen in IV drug users who have multiple holes in their legs
What happens in / causes varicose (venous) eczema?
- valves usually prevent backflow of blood
- if there is valvular damage in the legs (i.e. past DVTs / cellulitis) then blood will pool in the legs
- substances seep out of the blood into the skin, causing lower limb oedema
Who is usually affected by varicose eczema?
more common in the elderly due to ageing valves that have deteriorated
What is an alternative name for varicose eczema?
Stasis dermatitis as it occurs due to stasis or blood pooling as a result of insufficient venous return
varicose eczema refers to the fact that a common cause is varicose veins
What are the symptoms of varicose eczema?
- skin appears thin, brown & tissue-like (fine fissuring)
- erythematous plaques
- scaling
- pruritis
- skin becomes very dry and tightens, making it become thicker, particularly at the ankles
- may be open sores / ulcers due to weak skin, other areas become swollen
What is lipodermatosclerosis as a complication of varicose eczema?
it is a form of panniculitis (inflammation of the fat layer under the skin) that causes pain, hardening of the skin, erythema, swelling and a tapering of the legs above the ankles
this is known as the “upside down champagne bottle” sign
Why does the skin appear brown (hyperpigmented) in varicose eczema?
this is due to haemosiderin deposition
this is an iron breakdown product that comes from degradation of RBCs within the interstitial spaces in the epidermis & dermis
What is dermatitis herpetiformis?
Why does it have this name?
it is a rare and persistent immunobullous disease that has been linked to coeliac disease
the name is derived from the tendency for blisters to appear in clusters, resembling herpes simplex
but this is NOT due to viral infection
What are the clinical features of dermatitis herpetiformis?
- symmetrical distribution
- prurigo (extremely itchy papules) and vesicles
- often appear in groups
- often eroded/crusted due to immediate scratching
- lesion resolve to leave post-inflammatory hyper/hypo-pigmentation
What causes dermatitis herpetiformis?
Both coeliac disease and dermatitis herpetiformis are due to intolerance to the gliadin fraction of gluten
gluten triggers production of IgA antibodies and an autoimmune process that targets the skin and gut
What people are at increased risk of developing venous eczema?
seen in middle-aged and older patients and associated with:
- history of DVT in affected limb
- history of cellulitis in affected limb
- chronic swelling of lower leg, exacerbated by hot weather & prolonged standing
- varicose veins
- venous leg ulcers
What are the clinical features of venous eczema?
it can form discrete patches or become confluent & circumferential
- itchy red, blistered / crusted plaques or dry fissured and scaly plaques on one or both legs
- orange-brown macular pigmentation due to haemosiderin deposition
- atrophie blanche
- “champagne bottle” shape of lower leg due to lipodermatosclerosis
What is atrophie blanche?
white irregular scars surrounded by red spots
What is nodular prurigo and what is it characterised by?
It is a skin condition characterised by very itchy firm lumps
It is the most severe form of prurigo and it is not known why the lumps appear
Who tends to be affected by nodular prurigo?
Both sexes equally affected and most commonly seen in adults aged 20-60
80% of patients have a personal or family history of atopic dermatitis, asthma or hay fever
What are the clinical features of nodular prurigo?
- firm lumps that are 1-3 cm in diameter with a raised warty surface
- lesion may start as smaller red, itchy bump
- crusting or scaling may cover recently scratched lesions
- skin between nodules is often dry
- itch is very intense and can last for hours
- lesions are usually grouped and numerous (2-200)
- usually start on lower arms and legs and are worse on outer aspects
What is lichen planus?
a chronic inflammatory skin condition affecting the skin and mucosal surfaces
there are many different types
it is a T cell-mediated autoimmune disorder in which inflammatory cells attack an unknown protein within the skin and mucosal keratinocytes
What is the clinical presentation of lichen planus like?
- papules & polygonal plaques are shiny, flat-topped and firm on palpation
- plaques are crossed by fine white lines called Wickham striae
- size ranges from pinpoint to larger than a centimetre
- distribution can be scattered, clustered, linear, annular or actinic
- location can be anywhere, but most often the front of the wrists, lower back & ankles
What are the 4 different topical steroids often used for skin conditions?
In order of increasing strength:
- hydrocortisone
- eumovate
- betnovate
- dermovate
When is topical hydrocortisone typically used?
this is a very weak topical steroid which tends to be used in children and on thin skin (e.g. eyelids)
When does topical eumovate tend to be used?
This is a moderately potent topical corticosteroid that tends to be used for eczema affecting the face and groin
When does topical dermovate tend to be used?
this is the strongest topical steroid and is used for flares on the body and on the palms / soles of the feet
it SHOULD NOT be used on the face
When does topical betnovate tend to be used?
this tends to be used for eczema affecting the body