Dermatology Flashcards
What does it mean if a skin lesion is described as being ‘acral’ in its distribution?
Affecting distal areas- hands and feet
What dermatological condition do you classically associated with target lesions?
Erythema multiforme
How do annular and target lesions differ in their appearance?
Annular lesions are circle/ ring shaped (usually middle part spared)
Target lesions are concentric rings of varying colour and look like a dartboard / bullseye
When assessing the colour of a lesion, can use the term ‘purpura’ to describe a reddish/ purple discolouration of the skin. Name 2 types of purpura?
Petechiae and ecchymosis
What is key to remember about how lichenification of the skin looks?
Roughening of the skin with exaggerated normal skin lines
What distinguishes a hypertrophic scar from a keloid scar?
Hypertrophic scar = hyperproliferation of scar tissue WITHIN the wound boundary.
Keloid scar = hyperproliferation of scar tissue BEYOND the wound boundary.
Striae progress in colour from what.. to what.. to what..?
Purple -> Pink -> White
What does alopecia areata look like?
Well defined patches of hair loss with surrounding normal hair
Excess hair growth can be described as hirsutism and hypertrichosis- what is the difference?
Hirsutism is androgen-dependent excess hair growth in a female
Hypertrichosis is non-androgen dependent pattern of excessive hair growth
What are open and closed comedones more commonly known as?
Open comedones- blackheads
Closed comedones- whiteheads
The epidermis contains which 4 major cell types?
Keratinocytes, Langerhans cells, Melanocytes and Merkel cells
Tell me about UVA and UVB
UVA- longer wavelength, penetrates deeper and through window glass A = ageing (damages elastic fibres) and carcinogenic
UVB- shorter wavelength causes burning not as carcinogenic
B= burning
Outline Fitzpatrick skin types
1- always burns, never tans 2- usually burns, sometimes tans 3- sometimes burns, usually tans 4- never burns, always tans 5- brown skin 6- black skin
What is the progression from a mole (benign melanocytic naevus) to malignant melanoma?
Congenital and acquired melanocytic naevi (benign) -> atypical (dysplastic) melanocytic naevi -> malignant melanoma in situ (Lentigo malinga) -> malignant melanoma
What is malignant melanoma in situ called?
Lentigo maligna (but note that this is not the same as Lentigo maligna melanoma so do not get them mixed up!)
What are seborrhoeic keratoses and how are they classically described?
Benign epidermal skin lesions seen in older people. ‘Stuck on’ and ‘warty’ looking appearance.
What is the commonest form of skin cancer?
Basal cell carcinoma (BCC)
What are BCCs also known as?
Rodent ulcers
Where do you typically see BCCs?
Typically on the face in elderly or middle-aged patients. They mainly occur on light-exposed sites, commonly around the nose, the inner canthus of the eyelids and the temple
What are some of the risk factors for BCC?
UV exposure, history of frequent or severe sunburn in childhood, skin type 1, increasing age, male sex, immunosuppression, previous Hx of skin cancer and genetic predisposition
How fast do BCCs grow and do they metastasise?
They are a slow growing and locally invasive malignant tumour of the epidermal keratinocytes and only RARELY metastasise
What is the most common type of BCC?
Nodular
How are nodular BCCs classically described?
Small skin-coloured papule or nodule that shows fine telangiectasia and a glistening pearly rolled edge and central depression. The superficial branching telangiectasia are characteristic and are seen on dermoscopy as ‘arborizing’
What subtype of BCC more commonly occurs in younger patients? And how do these tend to present?
Superficial (plaque like). They present most frequently on the trunk as a slowly expanding pink-red patch.
When taking a history for a skin lesion, in terms of BCC skin cancer, over what time period does the lesion present?
Takes months-years to present
What should you do if you suspect a BCC?
Make a routine referral to dermatology
What is the management of a BCC?
If possible, complete excision is the best Tx as this allows a histological check on the adequacy of removal. If excision is difficult, radiotherapy is suitable for those aged >60 years. Often no further investigations/ staging is needed for BCC once they have been excised.
Tell me about Mohs micrographic surgery and for what type of BCC is this procedure gold-standard?
Mohs micrographic surgery - excision of the lesion and tissue progressively until specimens are microscopically free of tumour - used for high-risk, recurrent tumours. It also tends to be gold-standard for infiltrative BCC.
What is a squamous cell carcinoma?
A locally invasive malignant tumour of the epidermal keratinocytes which has the potential to metastasise
What are the risk factors for SCC?
Excessive UV exposure, pre-malignant skin conditions (e.g. actinic keratosis), Bowen’s disease, Immunosuppression, smoking, chronic inflammation (long standing leg ulcers, wound scars), genetic conditions
How do SCCs present?
Keratitis (e.g. scaly, crusty), ill-defined nodule which may ulcerated. Usually increase in size over weeks-months
What is the premalignant form of SCC?
Actinic (solar) keratosis
What is SCC in-situ (intraepidermal SCC) known as?
Bowen’s disease
What is the management of SCC?
Surgical excision is the Tx of choice- with 4mm margins if lesion <20mm in diameter. If lesion >20mm then margins should be 6mm. Mohs micrographic surgery may be necessary for ill-defined, large, recurrent tumours (high risk patients and in cosmetically important sites). Radiotherapy for large, non-resectable tumours
What patient demographic (age/gender) does Bowen’s disease tend to occur in? And what is the risk of it developing into invasive skin cancer
More common in elderly females. There is around a 3% chance of developing invasive skin cancer.
What causes actinic keratosis and what are the risk factors for it?
Induced by chronic exposure to UV radiation. Risk factors include: old age, male sex, cumulative sun exposure, fair skin, immunosuppression, genetic factors
How do actinic keratoses present?
Small, crusty or scaly, roughened patches of skin, usually <1cm in diameter found on sun-exposed skin (e.g. temples of head) and are often easier to palpate than see.
What is the management of actinic keratosis?
5-flurouracil cream (5-FU) in various concentrations applied daily for 1-4 weeks or with salicylic acid (for more hyperkeratotic lesions) for 6-12 weeks is an effective approach.
Other Tx options include: Imiquimod cream, ingenol mebutate gel, cryotherapy
What must you warn patients about if you are going to prescribe them 5-FU cream for actinic keratosis?
Warn them about the likely inflammatory reaction during therapy. The skin will become red and inflamed- sometimes topical hydrocortisone is given following 5-FU to settle the inflammation.
What is malignant melanoma?
An invasive malignant tumour of the epidermal melanocytes which has the potential to metastasise
What are the risk factors for malignant melanoma?
Age, Excessive UV exposure (intermittent exposure sunburn), skin type 1, history of multiple moles or atypical moles, and family history or previous history of melanoma.
What is ABCDE in relation to malignant melanoma?
Asymmetrical shape Border irregularity Colour irregularity Diameter >6mm Evolution of the lesion (e.g. change in size/shape) Symptoms (e.g. bleeding, itching)
In addition to the ABCDE for malignant melanoma, what other checklist can be used to assess a lesion?
Glasgow 7 point checklist which separates major and minor features
Describe the Glasgow 7 point checklist for malignant melanoma
Major criteria: change in size, change in shape, change in colour
Minor criteria: diameter >7mm, inflammation, oozing or bleeding, altered sensation (e.g. itch)
Name the 4 main subtypes of melanoma
Superficial spreading
Nodular
Lentigo maligna melanoma
Acral lentiginous malignant melanoma
What subtype of malignant melanoma is the most aggressive?
Nodular melanoma
What is the most common type of malignant melanoma?
Superficial spreading
Describe superficial spreading malignant melanoma
Make up 70% of cases. Common mainly on the lower limbs but also the arms, back and chest in young and middle-aged adults, related to intermittent high-intensity UV exposure
Describe nodular malignant melanoma
Second commonest. Common on the trunk in young and middle-aged adults, related to intermittent high-intensity UV exposure. Red or black lump or lump which bleeds or oozes.
Describe lentigo maligna melanoma
Common on the face in the elderly population, related to long-term cumulative UV exposure
Describe acral lentiginous malignant melanoma
Common on the palms, soles and nail beds in elderly population. No clear relation with UV exposure. Is the rest form of melanoma overall but is the commonest form of melanoma in people with dark skin.
What is the commonest form of malignant melanoma in people with dark skin?
Acral lentiginous malignant melanoma
What is Hutchinson’s sign?
Pigmentation of the nail bed (Subungual pigmentation) affecting the proximal nail fold which suggests melanoma (acral type)
What is the management of malignant melanoma?
Suspicious lesions should undergo excision biopsy. The lesion should be removed completely. Once the diagnosis is confirmed the pathology report should be reviewed to determine whether further re-excision of margins is required. Margins of excision is also related to Breslow thickness.
What is the most important prognostic factor for malignant melanoma?
The Breslow thickness (depth of abnormal melanocytes within the dermis)
When should you offer sentinel lymph node biopsy in malignant melanoma?
If the Breslow depth is >1.0mm
What treatment is used for metastatic disease in malignant melanoma?
Chemotherapy
What is a keratoacanthoma? And how is it classically described?
A benign epithelial tumour. They are more common with advancing age and rare in young people. Typically said to look like a volcano or crater. Initially a smooth dome-shaped papule, rapidly grows to become a crater centrally filled with keratin. Spontaneous regression within 3 months is common, often resulting in a scar. May be difficult clinically to exclude an SCC so should be urgently excised and removal may prevent scarring.
What is the difference between cellulitis and erysipelas?
Cellulitis involves the deep subcutaneous tissue
Erysipelas is an acute superficial form of cellulitis and involves the dermis and upper subcutaneous tissue
What organism is the most common cause of cellulitis/ erysipelas?
Streptococcus pyogenes (a type of group A strep)
How does cellulitis present?
Any age, pain is a common feature. The legs followed by the face are the most common sites. Facial involvement tends to be more superficial i.e. erysipelas. Rash is normally unilateral, except on the face where it is occasionally bilateral. Local signs of inflammation. May be systemically unwell with fever, malaise or rigors
How is erysipelas clinically distinguished from cellulitis?
Erysipelas is distinguished from cellulitis by a well-defined, red raised border (i.e. the edge is more well-demarcated in erysipelas than in cellulitis).
What are the differential diagnoses for cellulitis?
DVT, Gravitational eczema, Contact allergic dermatitis, Panniculitis (including acute lipodermatosclerosis)
How might you distinguish cellulitis from gravitational eczema?
Many patients with gravitational eczema are incorrectly diagnosed as having bilateral cellulitis (which is extremely rare)- so if it is bilateral then it is less likely to be cellulitis (which is normally unilateral) and would be more likely to be e.g. gravitational eczema
What investigations should you do if you suspect cellulitis?
Skin swabs should be taken, and if present from open areas/ areas of exudate, although in many cases results are negative. If bullseye or abscesses form, culturing the fluid from inside these lesions yields an organism in >90% of cases. Blood cultures for inpatients.
Give some circumstances/ examples of when you would admit a patient with cellulitis
Cellulitis associated with marked systemic upset e.g. fever, vomiting, tachycardia and hypotension
Spreading cellulitis that is not responding to oral medication
Lymphangitis
Would also have a lower threshold for admitting those more at risk e.g. infants, very young children, elderly, immunocompromised or sig co-morbidities
What is the first-line treatment for uncomplicated cellulitis (and erysipelas)?
Flucloxacillin 500mg QDS for 7-10 days
Other than antibiotic Tx, how else would you manage cellulitis/ erysipelas?
Adequate analgesia, (for the lower leg- rest and elevate the affected area where possible to reduce pain, swelling and damage to the venous system), mark out the extent of the cellulitis and review the patient while on Tx.
What is the management of recurrent cellulitis and how many attacks of cellulitis per year are needed for this prophylaxis?
Antibiotic prophylaxis should be offered to patients who have two or more attacks of cellulitis per year. Penicillin V should be the first choice.
What are some of the complications of cellulitis?
Local necrosis, abscess and septicaemia
Lymphangitis
Deep seated infection e.g. fasciitis and myositis
What is lymphangitis?
May be a complication of cellulitis / erysipelas. It presents with a red line originating from the cellulitis and spreading proximally to lymph node along the lymphatic vessels
Briefly describe staphylococcal scalded skin syndrome (SSSS)
It is an uncommon, superficial blistering skin condition characterised by widespread erythema and exfoliation, mainly occurring in children <5 years old, although older children and adults can be affected
What is SSSS caused by?
Exfoliative toxins (epidermolytic toxins A and B) of some strains of Staphylococcus aureus.
How does SSSS tend to present?
Fever and irritability are common, but patients do not appear overly unwell. Macular erythema is followed by diffuse, confluence erythema with bullae which rupture easily. There is marked epidermal exfoliation with the skin peeling off in sheets, leaving exposed moist bright-red tender areas.
What is the Nikolsky sign and is it positive or negative in SSSS?
It is when the gentle stroking of the skin causes the skin to separate at the epidermis. In SSSS the Nikolsky sign is positive.
How is SSSS differentiated from TEN? - Toxic epidermal necrolysis?
SSSS differs from the more severe, and generally drug-induced TEN, in that the cleavage site in SSSS is INTRAEPIDERMAL, opposed to TEN which involves necrosis of the entire epidermis.
How quickly does SSSS present and where on the body does it tend to occur?
Develops within a few hours to a few days and may be worse over the face, neck, axillae or groins. Perioral crusting is also typical.
What is the management of SSSS?
Requires prompt recognition and Tx. Same day contact should be made with the on-call dermatologist as hospital admission will almost certainly be required. IV antibiotics. Note: corticosteroids slow down healing and hence are NOT given for SSSS.
What is impetigo and what are the 2 main clinical forms?
It is a common contagious superficial bacterial infection of the skin. The 2 main clinical forms are non-bullous impetigo and bullous impetigo
Tell me about non-bullous vs bullous impetigo?
Non-bullous impetigo is caused by S.aureus, S.pyogens or a combination of both and accounts for the majority (~70%) of cases- often just referred to as ‘impetigo’.
Bullous impetigo is nearly always caused by S.aureus.
What age group is most commonly affected by impetigo?
It affects all age groups, but is most common in young children. The non-bullous form is most common in children aged 2-5 years, and bullous impetigo is most common in children under the age of 2.
How does non-bullous impetigo present?
Presents with thin-walled vesicles or pustules on an erythematous base (seldom seen O/E as they rupture quickly), which release exudate forming a golden yellow/brown crust. Usually asymptomatic but may be mildly itchy. The area around the mouth and nose is most commonly affected. Mucosal involvement is uncommon.
Describe the presentation of bullous impetigo
Most commonly affects infants. Small or large bullae arise over a short period of time. Lesions most often occur on the flexures, face, trunk and limbs. Flaccid fluid-filled vesicles and blisters which can persist for 2-3 days before rupturing, leaving a thin flat yellow/brown crust
