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
What is chronic plaque psoriasis and how does it present?
the most common presentation of psoriasis
presents as small to large, well-demarcated, red, scaly & thickened areas of skin
it is most likely to affect elbows, knees & lower back but can arise on any part of the body
What does it mean by plaque psoriasis being “scaly”?
it can appear silvery due to flakes of epidermis resting on the surface of the skin
What is the treatment of choice for plaque psoriasis?
Calcipotriol
this is a vitamin D analogue that comes in many forms:
- dovonex
- dovobet
- enstilar foam
- coal tar
- steroid shampoo / washes
Why are topical corticosteroids not used alone in psoriasis?
As soon as the steroids are stopped, the psoriasis is likely to return
Why aren’t patients with psoriasis all prescribed methotrexate?
Injections / biologics / methotrexate treatments are very expensive so a step-up approach is used
people are only prescribed these if all other previous treatments have failed
What additional steps are in place for patients taking methotrexate?
Most patients need to be on methotrexate for life
They are monitored every 3 months (bloods & LFTs) as it can cause anaemias and liver degradation
What skin conditions does methotrexate tend to be prescribed for?
inflammatory skin conditions such as psoriasis and eczema / dermatitis
also used for rheumatoid arthritis, psoriatic arthritis & other inflamamtory / autoimmune conditions
it is used at much higher doses as a chemotherapy agent for leukaemia & some other cancers
Who tends to be affected by acne vulgaris?
Most people will have it at some point in their life
It mainly affects adolescents (as young as 8) but it may persist, begin or become more severe in adulthood
What are the clinical features of acne vulgaris?
- most often affects the face but can spread to involve the neck, chest & back
- individual lesions are centred on the pilosebaceous unit
- several types of acne spots occur, often at the same time
- inflamed papules
- inflamed pustules
- inflamed nodules
- non-inflamed comedones
- non-inflamed pseudocysts
How do superficial and deeper lesions tend to present in acne vulgaris?
Superficial lesions:
- open and closed comedones (blackheads / whiteheads)
- papules (small, tender red bumps)
- pustules (white / yellow bumps)
Deeper lesions:
- nodules (large, painful red lumps)
- pseudo-cysts (cyst-like fluctuant swellings)
What is the treatment for mild acne?
topical anti-acne preparations, lasers and lights
What is the treatment for moderate and severe acne?
moderate:
- acne antibiotics - such as tetracyclines
- and/or antiandrogens (combined OCP)
severe:
- may require a course of oral isotretinoin
If a young woman presents with severe acne, what must be done before isotretinoin can be prescribed?
PREGNANCY TEST
isotretinoin is extremely teratogenic so a pregnancy test must be done before prescribing!
What are the contraindications to prescribing the OCP to treat acne?
hemiplegic migraine (migraine with aura)
this is an absolute contraindication as it could cause the patient to have a stroke
What are the stages involved in acne treatment?
- start with education
- treatment determined by severity
- topical treatment
- systemic treatment
- isotretinoin (effective but higher risk)
How often does isotretinoin treatment last for?
What are the adverse effects?
treatment is usually given for 4-6 months
it can be repeated, but there often isn’t a need for it
adverse effects include:
- teratogenic
- dryness of the mouth, lips and nose
- deranged LFTs / blood cholesterol
- ? mood problems (not very good evidence to support this)
What is Stevens-Johnson syndrome / toxic epidermal necrolysis?
They are variants of the same condition, distinct from erythema multiforme
SJS/TEN is a rare, acute, serious and potentially fatal skin reaction in which there are sheet-like skin and mucosal loss
What is the primary cause of Steven Johnson syndrome?
It is nearly always caused by medications
More than 100 drugs that cause this have been descirbed but it includes:
- allopurinol
- aminopenicillins
- antiepileptics
- piroxicam
What is the difference between Stevens-Johnson syndrome and toxic epidermal necrolysis?
they are categorised by the extent of skin detachment
- SJS < 10%
- SJS/TEN 10-30%
- TEN >30%
What symptoms precede SJS?
- fever
- stinging eyes
- pain on swallowing
these may precede SJS by 1-3 days
How does SJS tend to present?
- affects the trunk, neck, face and proximal extremities
- palms and soles indicate early involvement, which progresses to epidermal detachment
- there may also be desquamation of the lips (skin peeling off)
- skin lesions are usually tender, sometimes dusky red or bullous and irregular
Who is more likely to get SJS/TEN?
- anyone on medication can develop SJS/TEN unpredictably
- it can affect all age groups and all races
- slightly more common in females
- it is 100 times more common in association with HIV
Before the rash appears in SJS, what symptoms accompany the initial prodromal illness?
- fever >39 C
- sore throat / difficulty swallowing
- runny nose
- cough
- sore red eyes, conjunctivitis
- general aches and pains
After the initial prodromal illness phase, how does the rash present in SJS?
there is abrupt onset of a tender/painful red skin rash starting on the trunk and extending rapidly over hours to days onto the face and limbs
the maximum extent is usually reached by 4 days
What do the skin lesions look like in SJS?
the skin lesions may be:
- macules - flat, red and diffuse (measles-like spots) or purple (purpuric) spots
- diffuse erythema
- targetoid - as in erythema multiforme
- blisters - flaccid (i.e. not tense)
After blisters have formed in SJS, then what is done?
the blisters merge to form sheets of skin detachment, exposing red, oozing dermis
the Nikolsky sign is positive in areas of skin redness meaning that blisters and erosions appear when the skin is rubbed gently
What is the initial treatment for SJS?
it is a dermatological emergency
the patient becomes hypothermic and dehydrated
temperature is regulated by placing patient in a bearhugger with prophylactic antibiotics and IV fluids
What is a key distinguishing feature of tinea infection?
lesions have a raised border with central sparing
What is the treatment for tinea infections?
topical terbinafine or miconazole
it is treated for 2 weeks after the rash has gone or else it might come back
What is topical ketoconazole usually used to treat?
seborrhoeic dermatitis
What is topical metronidazole usually used to treat?
rosacea on the face
this is characterised by telangiectasia, pustles and blotchy red raised lesions
it is caused by demodex, a bug naturally found on the face, when we have an inflammatory reaction to it
What is topical tetracycline used to treat?
acne
What is seborrhoic dermatitis and how does it present?
an inflammatory reaction to yeast - Malassezia spp.
it presents with a fine scale (usually on the face or back of the neck)
the rash is most profuse on the nasolabial folds and scalp
Malassezia produces a lot of dandruff on the scalp which can come down onto the face and form a scale
What is the main difference between pemphigus and bullous pemphigoid?
Pemphigus:
- deep tense blisters that do not rupture easily
Bullous pemphigoid:
- superficial flaccid blisters that rupture easily
Why does pemphigus have a higher mortality than bullous pemphigoid?
Pemphagus has superficial, flaccid blisters that rupture easily
when they rupture, the patient is more likely to get an infection that could develop into sepsis
Who tends to get bullous pemphagoid/pemphagus?
- often presents in people over 80 years old
- more prevalent in patients with neurological disease, particualrly stroke, dementia and parkinson disease
How does pemphigoid tend to present?
How is it managed?
- severe itch
- large, tense bullae (fluid-filled blisters)
- blisters rupture to form crusted erosions
management usually involves topical/systemic steroids & dermatology input
What is a key diagnostic feature of scabies?
severe pruritis, especially in the finger web region
When do the symptoms of scabies tend to come on?
Who is more likely to be affected?
if it is the first episode, itch arises 4-6 weeks after transmission of a mite
residents from carehomes, hospitals, prisons and students are more at risk as there tends to be more sharing of towels, accessories etc.
What are potential complications of scabies?
secondary infection or “Norwegian scabies”
This involves a granola-like (crumbly and yellow) rash all over the body that is more common in immunosuppressed individuals
What is the first line treatment for scabies?
permethrin 5% dermal cream
