Dermatology

Question 1

Acanthosis nigricans

Describes symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin

Answer 1

Causes

gastrointestinal cancer

diabetes mellitus

obesity

polycystic ovarian syndrome

acromegaly

Cushing’s disease

hypothyroidism

familial

Prader-Willi syndrome

drugs: oral contraceptive pill, nicotinic acid

Question 2

Acne Rosacea

Features

typically affects nose, cheeks and forehead

flushing is often first symptom

telangiectasia are common

later develops into persistent erythema with papules and pustules

rhinophyma

ocular involvement: blepharitis

sunlight may exacerbate symptoms/

Answer 2

Management

topical metronidazole may be used for mild symptoms (i.e. Limited number of papules and pustules, no plaques)

topical brimonidine gel may be considered for patients with predominant flushing but limited telangiectasia

more severe disease is treated with systemic antibiotics e.g. Oxytetracycline

recommend daily application of a high-factor sunscreen

camouflage creams may help conceal redness

laser therapy may be appropriate for patients with prominent telangiectasia

patients with a rhinophyma should be referred to dermatology

Question 3

Acne

Acne vulgaris is a common skin disorder which usually occurs in adolescence. It typically affects the face, neck and upper trunk and is characterised by the obstruction of the pilosebaceous follicles with keratin plugs which results in comedones, inflammation and pustules.

Answer 3

A simple step-up management scheme often used in the treatment of acne is as follows:

single topical therapy (topical retinoids, benzoyl peroxide)

topical combination therapy (topical antibiotic, benzoyl peroxide, topical retinoid)

oral antibiotics:

tetracyclines: lymecycline, oxytetracycline, doxycycline

tetracyclines should be avoided in pregnant or breastfeeding women and in children younger than 12 years of age

erythromycin may be used in pregnancy

minocycline is now considered less appropriate due to the possibility of irreversible pigmentation

a single oral antibiotic for acne vulgaris should be used for a maximum of three months

a topical retinoid (if not contraindicated) or benzoyl peroxide should always be co-prescribed with oral antibiotics to reduce the risk of antibiotic resistance developing. Topical and oral antibiotics should not be used in combination

Gram-negative folliculitis may occur as a complication of long-term antibiotic use - high-dose oral trimethoprim is effective if this occurs

combined oral contraceptives (COCP) are an alternative to oral antibiotics in women

as with antibiotics, they should be used in combination with topical agents

Question 4

Actinic keratoses

Actinic, or solar, keratoses (AK) is a common premalignant skin lesion that develops as a consequence of chronic sun exposure

Features

small, crusty or scaly, lesions

may be pink, red, brown or the same colour as the skin

typically on sun-exposed areas e.g. temples of head

multiple lesions may be present

Answer 4

Management options include

prevention of further risk: e.g. sun avoidance, sun cream

fluorouracil cream: typically a 2 to 3 week course. The skin will become red and inflamed - sometimes topical hydrocortisone is given following fluorouracil to help settle the inflammation

topical diclofenac: may be used for mild AKs. Moderate efficacy but much fewer side-effects

topical imiquimod: trials have shown good efficacy

cryotherapy

curettage and cautery

Question 5

Alopecia

Alopecia may be divided into scarring (destruction of hair follicle) and non-scarring (preservation of hair follicle)

Answer 5

Scarring alopecia

trauma, burns

radiotherapy

lichen planus

discoid lupus

tinea capitis*

Non-scarring alopecia

male-pattern baldness

drugs: cytotoxic drugs, carbimazole, heparin, oral contraceptive pill, colchicine
nutritional: iron and zinc deficiency
autoimmune: alopecia areata

telogen effluvium

hair loss following stressful period e.g. surgery

trichotillomania

Question 6

Anti-histamines

Answer 6

Loratadine and cetirizine are non-sedating antihistamines meaning they are less sedating than alternatives such as chlorpheniramine

Important for meLess important

Loratadine is a non-sedating antihistamine - although it can cause sedation it is less likely to do so than other medications.

Chlorphenamine and promethazine are both useful antihistamines but are more likely to cause sedation than loratadine.

Buclizine is an antihistamine although it is more commonly used as an anti-emetic (in combination with paracetamol) for the relief of migraines.

Mirtazapine has antihistamine properties but is used primarily as an antidepressant and appetite stimulant.

Antihistamines (H1 inhibitors) are of value in the treatment of allergic rhinitis and urticaria.

Examples of sedating antihistamines

chlorpheniramine
As well as being sedating these antihistamines have some antimuscarinic properties (e.g. urinary retention, dry mouth).

Examples of non-sedating antihistamines

loratidine

cetirizine

Of the non-sedating antihistamines there is some evidence that cetirizine may cause more drowsiness than other drugs in the class.

Question 7

Basal cell carcinoma

Basal cell carcinoma (BCC) is one of the three main types of skin cancer. Lesions are also known as rodent ulcers and are characterised by slow-growth and local invasion. Metastases are extremely rare. BCC is the most common type of cancer in the Western world.

Answer 7

Features

many types of BCC are described. The most common type is nodular BCC, which is described here

sun-exposed sites, especially the head and neck account for the majority of lesions

initially a pearly, flesh-coloured papule with telangiectasia

may later ulcerate leaving a central ‘crater’

Referral

generally, if a BCC is suspected, a routine referral should be made

Management options:

surgical removal

curettage

cryotherapy

topical cream: imiquimod, fluorouracil

radiotherapy

Question 8

Bullous disorders

Answer 8

Causes of skin bullae

congenital: epidermolysis bullosa
autoimmune: bullous pemphigoid, pemphigus

insect bite

trauma/friction

drugs: barbiturates, furosemide

Question 9

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

Answer 9

Bullous pemphigoid is more common in elderly patients.

Features include

itchy, tense blisters typically around flexures

the blisters usually heal without scarring

mouth is usually spared*

Skin biopsy

immunofluorescence shows IgG and C3 at the dermoepidermal junction

Management

referral to dermatologist for biopsy and confirmation of diagnosis

oral corticosteroids are the mainstay of treatment

topical corticosteroids, immunosuppressants and antibiotics are also used

Question 10

Burns pathology

Answer 10

Extensive burns

Haemolysis due to damage of erythrocytes by heat and microangiopathy

Loss of capillary membrane integrity causing plasma leakage into interstitial space

Extravasation of fluids from the burn site causing hypovolaemic shock (up to 48h after injury)- decreased blood volume and increased haematocrit

Protein loss

Secondary infection e.g. Staphylococcus aureus

ARDS

Risk of Curlings ulcer (acute peptic stress ulcers)

Danger of full thickness circumferential burns in an extremity as these may develop compartment syndrome

Question 11

Eczema herpeticum

Answer 11

Eczema herpeticum describes a severe primary infection of the skin by herpes simplex virus 1 or 2.

It is more commonly seen in children with atopic eczema and often presents as a rapidly progressing painful rash.

On examination, monomorphic punched-out erosions (circular, depressed, ulcerated lesions) usually 1–3 mm in diameter are typically seen.

As it is potentially life-threatening children should be admitted for IV aciclovir.

Question 12

Erythema multiforme

Erythema multiforme is a hypersensitivity reaction which is most commonly triggered by infections. It may be divided into minor and major forms.

Answer 12

Features

target lesions

initially seen on the back of the hands / feet before spreading to the torso

upper limbs are more commonly affected than the lower limbs

pruritus is occasionally seen and is usually mild

Causes

viruses: herpes simplex virus (the most common cause), Orf*

idiopathic

bacteria: Mycoplasma, Streptococcus
drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine

connective tissue disease e.g. Systemic lupus erythematosus

sarcoidosis

malignancy

Question 13

Erythroderma

Erythroderma is a term used when more than 95% of the skin is involved in a rash of any kind.

Answer 13

Causes of erythroderma

eczema

psoriasis

drugs e.g. gold

lymphomas, leukaemias

idiopathic

Question 14

Erythema nodosum

Overview

inflammation of subcutaneous fat

typically causes tender, erythematous, nodular lesions

usually occurs over shins, may also occur elsewhere (e.g. forearms, thighs)

usually resolves within 6 weeks

lesions heal without scarring

Answer 14

Causes

infection

streptococci

tuberculosis

brucellosis

systemic disease

sarcoidosis

inflammatory bowel disease

Behcet’s

malignancy/lymphoma

drugs

penicillins

sulphonamides

combined oral contraceptive pill

pregnancy

Question 15

Fungal nail infections

Onychomycosis is fungal infection of the nails. This may be caused by

dermatophytes - mainly Trichophyton rubrum, accounts for 90% of cases

yeasts - such as Candida

non-dermatophyte moulds

Answer 15

Investigation

nail clippings

scrapings of the affected nail

the false-negative rate for cultures are around 30%, so repeat samples may need to be sent if the clinical suspicion is high

Management

do not need to be treated if it is asymptomatic and the patient is not bothered by the appearance

diagnosis should be confirmed by microbiology before starting treatment

dermatophyte infection:

oral terbinafine is currently recommended first-line with oral itraconazole as an alternative

6 weeks - 3 months therapy is needed for fingernail infections whilst toenails should be treated for 3 - 6 months

treatment is successful in around 50-80% of people

Candida infection:

mild disease should be treated with topical antifungals (e.g. Amorolfine) whilst more severe infections should be treated with oral itraconazole for a period of 12 weeks

if topical topical treatment is given treatment should be continued for 6 months for fingernails and 9-12 months for toenails

Question 16

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. Twenty percent of cases occur spontaneously without prior family history.

Answer 16

There are 4 main diagnostic criteria. If the patient has 2 then they are said to have a possible diagnosis of HHT. If they meet 3 or more of the criteria they are said to have a definite diagnosis of HHT:

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

Question 17

Hirsutism and hypertrichosis

Hirsutism is often used to describe androgen-dependent hair growth in women, with hypertrichosis being used for androgen-independent hair growth

Answer 17

Polycystic ovarian syndrome is the most common causes of hirsutism. Other causes include:

Cushing’s syndrome

congenital adrenal hyperplasia

androgen therapy

obesity: thought to be due to insulin resistance

adrenal tumour

androgen secreting ovarian tumour

drugs: phenytoin, corticosteroids

Causes of hypertrichosis

drugs: minoxidil, ciclosporin, diazoxide

congenital hypertrichosis lanuginosa, congenital hypertrichosis terminalis

porphyria cutanea tarda

anorexia nervosa

Management of hirsutism

advise weight loss if overweight

cosmetic techniques such as waxing/bleaching - not available on the NHS

consider using combined oral contraceptive pills such as co-cyprindiol (Dianette) or ethinylestradiol and drospirenone (Yasmin). Co-cyprindiol should not be used long-term due to the increased risk of venous thromboembolism

facial hirsutism: topical eflornithine - contraindicated in pregnancy and breast-feeding

Question 18

Impetigo

Features

‘golden’, crusted skin lesions typically found around the mouth

very contagious

Answer 18

Management

Limited, localised disease

topical fusidic acid is first-line

topical retapamulin is used second-line if fusidic acid has been ineffective or is not tolerated

MRSA is not susceptible to either fusidic acid or retapamulin. Topical mupirocin (Bactroban) should, therefore, be used in this situation

Extensive disease

oral flucloxacillin

oral erythromycin if penicillin-allergic

children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic treatment

Question 19

Retinoids Isotretinoin

Answer 19

Isotretinoin is an oral retinoid used in the treatment of severe acne. Two-thirds of patients have a long-term remission or cure following a course of oral isotretinoin.

Adverse effects

teratogenicity: females should ideally be using two forms of contraception (e.g. Combined oral contraceptive pill and condoms)

dry skin, eyes and lips/mouth: the most common side-effect of isotretinoin

low mood*

raised triglycerides

hair thinning

nose bleeds (caused by dryness of the nasal mucosa)

intracranial hypertension: isotretinoin treatment should not be combined with tetracyclines for this reason

photosensitivity

Question 21

Lichen planus

sclerosus: itchy white spots typically seen on the vulva of elderly women

Answer 21

Lichen

planus: purple, pruritic, papular, polygonal rash on flexor surfaces. Wickham’s striae over surface. Oral involvement common

Lichen planus is a skin disorder of unknown aetiology, most probably being immune-mediated.

Features

itchy, papular rash most common on the palms, soles, genitalia and flexor surfaces of arms

rash often polygonal in shape, with a ‘white-lines’ pattern on the surface (Wickham’s striae)

Koebner phenomenon may be seen (new skin lesions appearing at the site of trauma)

oral involvement in around 50% of patients: typically a white-lace pattern on the buccal mucosa

nails: thinning of nail plate, longitudinal ridging

Lichenoid drug eruptions - causes:

gold

quinine

thiazides

Management

topical steroids are the mainstay of treatment

benzydamine mouthwash or spray is recommended for oral lichen planus

extensive lichen planus may require oral steroids or immunosuppression

Question 22

Livedo reticularis

Livedo reticularis describes an purplish, non-blanching, reticulated rash caused by obstruction of the capillaries resulting in swollen venules.

Answer 22

Causes

idiopathic (most common)

polyarteritis nodosa

systemic lupus erythematosus

cryoglobulinaemia

antiphospholipid syndrome

Ehlers-Danlos Syndrome

homocystinuria

Question 23

Pityriasis versicolor

Pityriasis versicolor, also called tinea versicolor, is a superficial cutaneous fungal infection caused by Malassezia furfur (formerly termed Pityrosporum ovale)

Answer 23

Features

most commonly affects trunk

patches may be hypopigmented, pink or brown (hence versicolor). May be more noticeable following a suntan

scale is common

mild pruritus

Predisposing factors

occurs in healthy individuals

immunosuppression

malnutrition

Cushing’s

Management

topical antifungal. NICE Clinical Knowledge Summaries advise ketoconazole shampoo as this is more cost effective for large areas

if failure to respond to topical treatment then consider alternative diagnoses (e.g. send scrapings to confirm the diagnosis) + oral itraconazole

Question 24

Port wine stains

Answer 24

Port wine stains are a vascular birthmark that do not spontaneoulsy resolve

Important for meLess important

The correct answer here is port wine stain. These typically occur on the face as a purplish/red macule with irregular contours. They can be associated with intracranial vascular abnormalities like Sturge-Weber-Syndrome. They do not spontaneously resolve and can become darker or lumpy in later life. Treatment is with cosmetics or laser therapy.

Strawberry naevus or capillary haemangioma appear as a small red patch which develops in the first month of life, increasing in size until around 9 months and becoming more vascular. They are not present at birth and regress spontaneously.

Salmon patches or stork marks are pink telangiectatic macules present at birth and commonly found on the forehead or back of neck. They do not require treatment and often self-resolve. They are not associated with underlying conditions.

Mongolian blue spots are areas of bluish discolouration over the lower back and buttock which often disappear by 1 year of age. They should be documented and highlighted to parents as they can be mistake for bruising.

Melanocytic naevi are raised brown/black nodules which can be hairy and up to 20cm in diameter. There is a risk of developing melanomas from these and so they should be closely monitored.

Question 25

Pruritis

Answer 25

Condition Notes Liver disease History of alcohol excess Stigmata of chronic liver disease: spider naevi, bruising, palmar erythema, gynaecomastia etc Evidence of decompensation: ascites, jaundice, encephalopathy Iron deficiency anaemia Pallor Other signs: koilonychia, atrophic glossitis, post-cricoid webs, angular stomatitis Polycythaemia Pruritus particularly after warm bath 'Ruddy complexion' Gout Peptic ulcer disease Chronic kidney disease Lethargy & pallor Oedema & weight gain Hypertension Lymphoma Night sweats Lymphadenopathy Splenomegaly, hepatomegaly Fatigue Other causes: hyper- and hypothyroidism diabetes pregnancy 'senile' pruritus urticaria skin disorders: eczema, scabies, psoriasis, pityriasis rosea

Question 26

Psoriasis management

Answer 26

NICE released guidelines in 2012 on the management of psoriasis and psoriatic arthropathy. Please see the link for more details. Management of chronic plaque psoriasis regular emollients may help to reduce scale loss and reduce pruritus first-line: NICE recommend a potent corticosteroid applied once daily plus vitamin D analogue applied once daily (applied separately, one in the morning and the other in the evening) for up to 4 weeks as initial treatment second-line: if no improvement after 8 weeks then offer a vitamin D analogue twice daily third-line: if no improvement after 8-12 weeks then offer either: a potent corticosteroid applied twice daily for up to 4 weeks or a coal tar preparation applied once or twice daily short-acting dithranol can also be used

Question 27

Purpura

Answer 27

Children * Meningococcal septicaemia * Acute lymphoblastic leukaemia * Congenital bleeding disorders * Immune thrombocytopenic purpura * Henoch-Schonlein purpura * Non-accidental injury Adults * Immune thrombocytopenic purpura * Bone marrow failure (secondary to leukaemias, myelodysplasia or bone metastases) * Senile purpura * Drugs (quinine, antiepileptics, antithrombotics) * Nutritional deficiencies (vitamins B12, C and folate)

Question 28

Pyoderma gangrenosum

Answer 28

Features typically on the lower limbs initially small red papule later deep, red, necrotic ulcers with a violaceous border may be accompanied systemic symptoms e.g. Fever, myalgia Causes\* idiopathic in 50% inflammatory bowel disease: ulcerative colitis, Crohn's rheumatoid arthritis, SLE myeloproliferative disorders lymphoma, myeloid leukaemias monoclonal gammopathy (IgA) primary biliary cirrhosis

Question 29

Scabies ## Footnote Features widespread pruritus linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrist in infants, the face and scalp may also be affected secondary features are seen due to scratching: excoriation, infection

Answer 29

Management permethrin 5% is first-line malathion 0.5% is second-line give appropriate guidance on use (see below) pruritus persists for up to 4-6 weeks post eradication Patient guidance on treatment (from Clinical Knowledge Summaries) avoid close physical contact with others until treatment is complete all household and close physical contacts should be treated at the same time, even if asymptomatic launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites. The BNF advises to apply the insecticide to all areas, including the face and scalp, contrary to the manufacturer's recommendation. Patients should be given the following instructions: apply the insecticide cream or liquid to cool, dry skin pay close attention to areas between fingers and toes, under nails, armpit area, creases of the skin such as at the wrist and elbow allow to dry and leave on the skin for 8-12 hours for permethrin, or for 24 hours for malathion, before washing off reapply if insecticide is removed during the treatment period, e.g. If wash hands, change nappy, etc repeat treatment 7 days later

Question 30

Shin lesions ## Footnote The differential diagnosis of shin lesions includes the following conditions: erythema nodosum pretibial myxoedema pyoderma gangrenosum necrobiosis lipoidica diabeticorum

Answer 30

Below are the characteristic features: Erythema nodosum symmetrical, erythematous, tender, nodules which heal without scarring most common causes are streptococcal infections, sarcoidosis, inflammatory bowel disease and drugs (penicillins, sulphonamides, oral contraceptive pill) Pretibial myxoedema symmetrical, erythematous lesions seen in Graves' disease shiny, orange peel skin Pyoderma gangrenosum initially small red papule later deep, red, necrotic ulcers with a violaceous border idiopathic in 50%, may also be seen in inflammatory bowel disease, connective tissue disorders and myeloproliferative disorders Necrobiosis lipoidica diabeticorum shiny, painless areas of yellow/red skin typically on the shin of diabetics often associated with telangiectasia

Question 31

Soles of the feet

Answer 31

The table below gives characteristic exam question features for conditions affecting the soles of the feet Diagnosis Notes Verrucas Secondary to the human papilloma virus Firm, hyperkeratotic lesions Pinpoint petechiae centrally within the lesions May coalesce with surrounding warts to form mosaic warts Tinea pedis More commonly called Athlete's foot Affected skin is moist, flaky and itchy Corn and calluses A corn is small areas of very thick skin secondary to a reactive hyperkeratosis A callus is larger, broader and has a less well defined edge than a corn Keratoderma May be acquired or congenital Describes a thickening of the skin of the palms and soles Acquired causes include reactive arthritis (keratoderma blennorrhagica) Pitted keratolysis Affects people who sweat excessively Patients may complain of damp and excessively smelly feet Usually caused by Corynebacterium Heel and forefoot may become white with clusters of punched-out pits Palmoplantar pustulosis Crops of sterile pustules affecting the palms and soles The skin is thickened, red. Scaly and may crack More common in smokers Juvenile plantar dermatosis Affects children. More common in atopic patients with a history of eczema Soles become shiny and hard. Cracks may develop causing pain Worse during the summer

Question 32

Paraneoplastic syndromes associated with internal malignancies:

Answer 32

Skin disorder Associated malignancies Acanthosis nigricans -Gastric cancer Acquired ichthyosis - Lymphoma Acquired hypertrichosis lanuginosa -Gastrointestinal and lung cancer Dermatomyositis - Ovarian and lung cancer Erythema gyratum repens - Lung cancer Erythroderma - Lymphoma Migratory thrombophlebitis - Pancreatic cancer Necrolytic migratory erythema - Glucagonoma Pyoderma gangrenosum (bullous and non-bullous forms) - Myeloproliferative disorders Sweet's syndrome - Haematological malignancy e.g. Myelodysplasia - tender, purple plaques Tylosis - Oesophageal cancer

Question 33

Skin type

Answer 33

Skin type is an important risk factor for skin cancer. Skin types may be classified according to Fitzpatrick classification: I: Never tans, always burns (often red hair, freckles, and blue eyes) II: Usually tans, always burns III: Always tans, sometimes burns (usually dark hair and brown eyes) IV: Always tans, rarely burns (olive skin) V: Sunburn and tanning after extreme UV exposure (brown skin, e.g. Indian) VI: Black skin (e.g. Afro-Caribbean), never tans, never burns

Question 34

Squamous cell carcinoma of the skin Squamous cell carcinoma is a common variant of skin cancer. Metastases are rare but may occur in 2-5% of patients.

Answer 34

Risk factors include: 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

Question 35

Toxic epidermal necrolysis Toxic epidermal necrolysis (TEN) is a potentially life-threatening skin disorder that is most commonly seen secondary to a drug reaction. In this condition the skin develops a scalded appearance over an extensive area. Some authors consider TEN to be the severe end of a spectrum of skin disorders which includes erythema multiforme and Stevens-Johnson syndrome

Answer 35

Features systemically unwell e.g. pyrexia, tachycardic positive Nikolsky's sign: the epidermis separates with mild lateral pressure Drugs known to induce TEN phenytoin sulphonamides allopurinol penicillins carbamazepine NSAIDs

Question 36

Venous ulceration Venous ulceration is typically seen above the medial malleolus

Answer 36

Investigations ankle-brachial pressure index (ABPI) is important in non-healing ulcers to assess for poor arterial flow which could impair healing a 'normal' ABPI may be regarded as between 0.9 - 1.2. Values below 0.9 indicate arterial disease. Interestingly, values above 1.3 may also indicate arterial disease, in the form of false-negative results secondary to arterial calcification (e.g. In diabetics) Management compression bandaging, usually four layer (only treatment shown to be of real benefit) oral pentoxifylline, a peripheral vasodilator, improves healing rate small evidence base supporting use of flavinoids little evidence to suggest benefit from hydrocolloid dressings, topical growth factors, ultrasound therapy and intermittent pneumatic compression

Question 37

Zinc deficiency

Answer 37

Features perioral dermatitis: red, crusted lesions acrodermatitis alopecia short stature hypogonadism hepatosplenomegaly geophagia (ingesting clay/soil) cognitive impairment