Dermatology Flashcards
What is Pyoderma gangrenosum ?
A Rare, non-infectious inflammatory disorder.
It is a neutrophilic dermatosis
what are Neutrophilic dermatoses skin conditions ?
skin conditions characterised by dense infiltration of neutrophils in the affected tissue and this is often seen on biopsy
what are the causes of pyoderma gangrenosum?
Idiopathic in 50%
IBD
RA or SLE
Haematological conditions (myeloproliferative disorders, lymphoma, myeloid leukaemia, monoclonal gammopathy)
Granulomatosis with polyangiitis
Primary biliary cirrhosis
What are the features of pyoderma gangrenosum?
Usually occurs on the lower limb (often at the site of a minor injury)
Usually starts quite suddenly as a small pustule, red bump or blood blister
In the later stages the skin then breaks down resulting in an ulcer which is often painful. The edge of the ulcer is often described as purple, villous and undermined. The ulcer itself may be deep and necrotic
May be accompanied by fever and myalgia
How is pyoderma gangrenosum diagnosed?
often made by the characteristic appearance, associations with other diseases, the presence of pathergy, histology results and when other diseases have been ruled out
histology is not specific and can vary depending on the time and site of the specimen but may be helpful in ruling out other causes of an ulcer.
How is pyoderma gangrenosum managed?
the potential for rapid progression is high in most patients and most doctors advocate oral steroids as first-line treatment
other immunosuppressive therapy, for example, ciclosporin and infliximab, have a role in difficult cases
any surgery should be postponed until the disease process is controlled on immunosuppression to risk worsening of the disease (pathergy)
What are the different forms of melanoma?
Superficial spreading
Nodular
Lentigo maligna
acral lentiginous
What are the features of lentigo maligna?
This is a form of melanoma in situ, typically seen in chronically sun-exposed skin, such as the forehead in older people. It classically has the appearance of a freckle, with some suspicious features such as an irregularly shaped border and variable pigmentation. Excision biopsy is preferred.
What are the features of Acral lentiginous melanoma?
Acral lentiginous melanoma is a rare form of the condition found under the nails, or the palms or soles. It is more commonly found in African-American and Asian people.
What are the features of desmoplastic melanoma?
Desmoplastic melanoma is a very rare form of melanoma. It often involves nerve fibres. Malignant cells in the dermis are surrounded by fibrous tissue and would present more with a flat or raised papule or nodule.
What are the features of nodular melanoma?
Nodular melanoma is the most aggressive form, and second commonest. It is found in sun-exposed skin, but generally in younger, middle-aged people, rather than the older people that lentigo maligna melanoma presents in. It typically appears as a red or black lump that bleeds or oozes.
What are the features of superficial spreading melanoma?
Superficial spreading melanoma is the most common form, accounting for 70% of cases. It tends to be found on the limbs and torso of young people. It presents as a growing mole with the typical diagnostic features of melanoma including variable pigmentation, irregular borders, increasing size, bleeding, or ulceration.
what are the major and minor diagnostic criteria for melanoma
Major
- change in size, shape or colour
Minor
- diameter >/= 7mm, inflammation, oozing or bleeding, altered sensation
How is melanoma treated?
excision biopsy
Once the diagnosis is confirmed the pathology reports should be reviewed to determine whether further re-excision of margins is required
What is Hereditary haemorrhagic telangiectasia?
Also known as Osler-Weber-Rendu syndrome, hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant condition characterised by multiple telangiectasia over the skin and mucous membranes.
What are the 4 main diagnostic criteria for hereditary haemorrhagic telangiectasia?
> epistaxis : spontaneous, recurrent nosebleeds
telangiectases: multiple at characteristic sites (lips, oral cavity, fingers, nose)
visceral lesions: for example gastrointestinal telangiectasia (with or without bleeding), pulmonary arteriovenous malformations (AVM), hepatic AVM, cerebral AVM, spinal AVM
family history: a first-degree relative with HHT
If they meet 3 or more they are said to have a definite diagnosis
What is a marker for carbamazepine induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese?
HLA B*1502
What is the predominant cell type involved in Stevens-Johnson syndrome and toxic epidermal necrolysis ?
They are delayed-hypersensitivity reaction - thus involving T-Cells
What is Stevens-Johnson syndrome?
Stevens-Johnson syndrome is a severe systemic reaction affecting the skin and mucosa that is almost always caused by a drug reaction.
What are the causes of stevens-johnson syndrome?
penicillin
sulphonamides
lamotrigine, carbamazepine, phenytoin
allopurinol
NSAIDs
oral contraceptive pill
What is Vitiligo?
An autoimmune condition which results in the loss of melanocytes and consequent depigmentation of the skin.
What are the features of Stevens-Johnson syndrome?
the rash is typically maculopapular with target lesions being characteristic
may develop into vesicles or bullae
Nikolsky sign is positive in erythematous areas - blisters and erosions appear when the skin is rubbed gently
mucosal involvement
systemic symptoms: fever, arthralgia
What age group does Vitiligo usually develop?
20 - 20 years
What conditions are associated with vitiligo?
type 1 diabetes mellitus
Addison’s disease
autoimmune thyroid disorders
pernicious anaemia
alopecia areata
What are the features of Vitiligo ?
well-demarcated patches of depigmented skin
the peripheries tend to be most affected
trauma may precipitate new lesions (Koebner phenomenon)
What is the management of vitiligo?
sunblock for affected areas of skin
camouflage make-up
topical corticosteroids may reverse the changes if applied early
there may also be a role for topical tacrolimus and phototherapy, although caution needs to be exercised with light-skinned patients
What is Koebner’s phenomenon?
It is observed in several skin conditions including vitiligo. It describes the appearance of new skin lesions on areas of the skin that have been traumatized. In vitiligo, this could be due to cuts, burns or abrasions. The underlying mechanism is thought to involve local changes in the immune response or skin environment which provoke melanocyte destruction.
What is the pathophysiology of psoriasis?
multifactorial and not yet fully understood
genetic: associated HLA-B13, -B17, and -Cw6. Strong concordance (70%) in identical twins
immunological: abnormal T cell activity stimulates keratinocyte proliferation. There is increasing evidence this may be mediated by a novel group of T helper cells producing IL-17, designated Th17. These cells seem to be a third T-effector cell subset in addition to Th1 and Th2
environmental: it is recognised that psoriasis may be worsened (e.g. Skin trauma, stress), triggered (e.g. Streptococcal infection) or improved (e.g. Sunlight) by environmental factors
what are the subtypes of psoriasis?
plaque psoriasis: the most common sub-type resulting in the typical well-demarcated red, scaly patches affecting the extensor surfaces, sacrum and scalp
flexural psoriasis: in contrast to plaque psoriasis the skin is smooth
guttate psoriasis: transient psoriatic rash frequently triggered by a streptococcal infection. Multiple red, teardrop lesions appear on the body
pustular psoriasis: commonly occurs on the palms and sole
What features, non skin, that are found in psoriasis?
nail signs: pitting, onycholysis
arthritis
what are the complications of psoriasis?
psoriatic arthropathy (around 10%)
increased incidence of metabolic syndrome
increased incidence of cardiovascular disease
increased incidence of venous thromboembolism
psychological distress
where are keloid scars most likely to form?
The sternum
What are keloid scars?
Keloid scars are a result of an overgrowth of dense fibrous tissue that usually develops after the healing of a skin injury. The scar extends beyond the borders of the original wound, does not regress and tends to recur after excision. The sternum, along with other areas such as shoulders, upper arms and earlobes, is particularly prone to keloid formation due to high tension in these areas.
what are predisposing factors for keloid scars?
ethnicity: more common in people with dark skin
occur more commonly in young adults, rare in the elderly
common sites (in order of decreasing frequency): sternum, shoulder, neck, face, extensor surface of limbs, trunk
Keloid scars are less likely if incisions are made along relaxed skin tension lines
What is the treatment for keloid scars?
early keloids may be treated with intra-lesional steroids e.g. triamcinolone
excision is sometimes required but careful consideration needs to given to the potential to create further keloid scarring
What is Seborrhoeic dermatitis?
Seborrhoeic dermatitis in adults is a chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a normal skin inhabitant, a fungus called Malassezia furfur (formerly known as Pityrosporum ovale).
What are the features of seborrhoeic dermatitis?
eczematous lesions on the sebum-rich areas: scalp (may cause dandruff), periorbital, auricular and nasolabial folds
otitis externa and blepharitis may develop
what conditions are associated with seborrhoeic dermatitis?
HIV
Parkinson’s disease
How is scalp seborrheic dermatitis treated?
the first-line treatment is ketoconazole 2% shampoo
over the counter preparations containing zinc pyrithione (‘Head & Shoulders’) and tar (‘Neutrogena T/Gel’) may be used if ketoconazole is not appropriate or acceptable to the person
selenium sulphide and topical corticosteroid may also be useful
How is face and body seborrhoeic dermatitis treated?
topical antifungals: e.g. ketoconazole
topical steroids: best used for short periods
difficult to treat - recurrences are common
what are common complications of seborrhoeic dermatitis?
Otitis externa and blepharitis
what are the two main types of dermatitis?
Irritant contact dermatitis
Allergic contact dermatitis?
What is irritant contact dermatitis?
Common - non-allergic reaction due to weak acids or alkalis (e.g. detergents). Often seen on the hands. Erythema is typical, crusting and vesicles are rare
What is allergic contact dermatitis?
allergic contact dermatitis: type IV hypersensitivity reaction. Uncommon - often seen on the head following hair dyes. Presents as an acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself. Topical treatment with a potent steroid is indicated
What is the most common skin cancer secondary to immunosupression?
Squamous cell carcinoma
what are the risk factors for squamous cell carcinoma?
excessive exposure to sunlight / psoralen UVA therapy
actinic keratoses and Bowen’s disease
immunosuppression e.g. following renal transplant, HIV
smoking
long-standing leg ulcers (Marjolin’s ulcer)
genetic conditions e.g. xeroderma pigmentosum, oculocutaneous albinism
What are the features of squamous cell carcinoma?
typically on sun-exposed sites such as the head and neck or dorsum of the hands and arms
rapidly expanding painless, ulcerate nodules
may have a cauliflower-like appearance
there may be areas of bleeding
what is the treatment for SCC?
Surgical excision with 4mm margins if lesion <20mm in diameter. If tumour >20mm then margins should be 6mm. Mohs micrographic surgery may be used in high-risk patients and in cosmetically important sites.
what are good prognostic features of SCC?
Well differentiated tumours
< 20 mm diameter
< 2mm deep
No associated diseases
what are poor prognostic features of SCC?
Poorly differentiated tumours
> 20mm in diameter
> 4mm deep
immunosuppression for whatever reason.
What is Bullous pemphigoid?
Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230.
What are the features of bullous pemphigoid?
- more common in elderly patients
features include: - itchy, tense blisters around flexures
- blisters usually heal without scarring
- typical no mucosal involvement
What would bullous pemphigoid show on skin biopsy?
immunofluorescence shows IgG and C3 at the dermoepidermal junction
What is the management of Bullous pemphigoid?
referral to a dermatologist for biopsy and confirmation of diagnosis
oral corticosteroids are the mainstay of treatment
topical corticosteroids, immunosuppressants and antibiotics are also used
What is Impetigo?
Impetigo is a superficial bacterial skin infection usually caused by either Staphylcoccus aureus or Streptococcus pyogenes. It can be a primary infection or a complication of an existing skin condition such as eczema (in this case), scabies or insect bites. Impetigo is common in children, particularly during warm weather.
what is the incubation period of impetigo?
4-10 days
what are the features of impetigo?
golden’, crusted skin lesions typically found around the mouth
very contagious
How is impetigo managed?
For people who are systemically well and none bullous - hydrogen peroxide 1% cream.
Topical antibiotic creams
topical fusidic acid
topical mupirocin should be used if fusidic acid resistance is suspected
MRSA is not susceptible to either fusidic acid or retapamulin. Topical mupirocin should, therefore, be used in this situation
Extensive disease - oral flucloxacillin or erythromycin if pen allergic
** children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic treatment
When is a skin patch test indicated?
Skin patch testing is the gold standard for diagnosing contact dermatitis, such as nickel allergy. It involves applying a small amount of various substances, including nickel, to the skin using adhesive patches. The patches are usually left on for 48 hours and then removed. The skin is then examined for signs of an allergic reaction.
What is pemphigus vulgaris
Pemphigus vulgaris is an autoimmune disease caused by antibodies directed against desmoglein 3, a cadherin-type epithelial cell adhesion molecule. It is more common in the Ashkenazi Jewish population.
When is a skin prick test indicated?
Skin prick tests are typically used to diagnose IgE-mediated allergies, such as food or pollen allergies. They involve pricking the skin with a needle or lancet that contains a small amount of a suspected allergen. A positive result appears as a wheal (a raised, red bump) at the site of testing within 15-20 minutes. However, this method isn’t suitable for diagnosing contact dermatitis because these reactions are not IgE-mediated.
what are the features of pemphigus vulgaris?
mucosal ulceration is common and often the presenting symptom. Oral involvement is seen in 50-70% of patients
skin blistering - flaccid, easily ruptured vesicles and bullae. Lesions are typically painful but not itchy. These may develop months after the initial mucosal symptoms. Nikolsky’s describes the spread of bullae following application of horizontal, tangential pressure to the skin
acantholysis on biopsy
what is the treatment of pemphigus vulgaris
steroids are first-line
immunosuppressants
What is the appearance of Livedo reticularis?
purplish, non-blanching reticulated rash caused by obstruction of the capillaries resulting in swollen venules
what can cause Livedo reticularis?
Idiopathic
Polyarteritis nodosa
SLE
Cryoglobulinaemia
Antiphospholipid syndrome
Ehlers-Danlos Syndrome
Homocystinuria
what is the most common skin cancer in renal transplant patients?
Squamous cell carcinoma of the skin - due to immunosuppression
what are the risk factors for squamous cell carcinoma?
excessive exposure to sunlight / psoralen UVA therapy
actinic keratoses and Bowen’s disease
immunosuppression e.g. following renal transplant, HIV
smoking
long-standing leg ulcers (Marjolin’s ulcer)
genetic conditions e.g. xeroderma pigmentosum, oculocutaneous albinism
what are the features of squamous cell carcinoma ?
typically on sun-exposed sites such as the head and neck or dorsum of the hands and arms
rapidly expanding painless, ulcerate nodules
may have a cauliflower-like appearance
there may be areas of bleeding
what are the surgical excision boarders for squamous cell carcinoma ?
Surgical excision with 4mm margins if lesion <20mm in diameter. If tumour >20mm then margins should be 6mm. Mohs micrographic surgery may be used in high-risk patients and in cosmetically important sites.
What pattern is hereditary haemorrhagic telangiectasia inherited
autosomal dominant
Twenty percent of cases occur spontaneously without prior family history.
What is Hereditary Haemorrhagic telangiectasia?
Also known as Osler-Weber-Rendu syndrome, hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant condition characterised by (as the name suggests) multiple telangiectasia over the skin and mucous membranes.
what are the diagnostic features of hereditary haemorrhagic telangiectasia?
4 main diagnostic criteria
3= possible diagnosis
3 or more = definite diagnosis
epistaxis : spontaneous, recurrent nosebleeds
telangiectases: multiple at characteristic sites (lips, oral cavity, fingers, nose)
visceral lesions: for example gastrointestinal telangiectasia (with or without bleeding), pulmonary arteriovenous malformations (AVM), hepatic AVM, cerebral AVM, spinal AVM
family history: a first-degree relative with HHT
what is pompholyx?
Pompholyx is a type of eczema which affects both the hands (cheiropompholyx) and the feet (pedopompholyx). It is also known as dyshidrotic eczema.
what are the features pompholyx?
small blisters on the palms and soles
pruritic
once blisters burst the skin may become dry and crack
what are the triggers of pompholyx eczema?
Humidity
Irritants
Lifestyle - smoking
Drug use - aspirin and COCP
fungal infections