Dermatology

Question 1

Describe.

Answer 1

Scalp Seborrheic Dermatitis

Question 2

Define Seborrheic Dermatitis.

Answer 2

Seborrhoeic dermatitis is a common, chronic, or relapsing form of eczema/dermatitis that mainly affects the sebaceous gland-rich regions of the scalp, face, and trunk.

Question 3

What is associated with seborrheic dermatitis?

Answer 3

• Seborrhoeic dermatitis often occurs in otherwise healthy patients
• However, the following factors are sometimes associated with severe adult seborrhoeic dermatitis:
  
  • Familial tendency to seborrhoeic dermatitis or a family history of psoriasis
  • Immunosuppression: organ transplant recipients, human immunodeficiency virus (HIV) infection, and patients with lymphoma
  • Neurological and psychiatric diseases: Parkinson’s disease, tardive dyskinesia, depression, epilepsy, facial nervepalsy, spinal cord injury, and congenital disorders such as Down syndrome

Question 4

What fungus is associated with seborrheic dermatitis?

Answer 4

Malassezia furfur

Question 5

What are clinical features of seborrheic dermatitis?

Answer 5

• Winter flares, improving in summer following sun exposure
• Minimal itch most of the time
• Combination oily and dry mid-facial skin
• Ill-defined localised scaly patches or diffuse scale in the scalp
• Blepharitis: scaly red eyelid margins
• Salmon-pink, thin, scaly, and ill-defined plaques in skin folds on both sides of the face
• Petal or ring-shaped flaky patches on the hairline and on anterior chest
• Rash in the armpits, under the breasts, in the groin folds, and genital creases
• Malassezia folliculitis (inflamed hair follicles) on the cheeks and upper trunk.

Question 6

How do we diagnose seborrheic dermatitis? How is it managed?

Answer 6

The diagnosis of seborrhoeic dermatitis is a clinical diagnosis based on the location, appearance, and behaviour of the lesions.

If the diagnosis is uncertain, a biopsy can be undertaken

General measures

• Educating the patient about the skin condition and appropriate skincare routine.
• Identifying modifiable lifestyle factors e.g. a high fruit intake is associated with less seborrheic dermatitis whereas stress may precipitate flare-ups.

Specific measures

Treatment of seborrhoeic dermatitis often involves several of the following options.

• Keratolytics: used to remove scale when necessary, e.g. salicylic acid, lactic acid, urea, propylene glycol.
• Topical antifungal agents: applied to reduce Malassezia e.g. ketoconazole, or ciclopirox shampoo and/or cream. Note, some strains of Malassezia are resistant to azole antifungals. Try zinc pyrithione (Head and Shoulders) or selenium sulphide.

Scalp treatment

• Ketoconazole 2% shampoo (twice a week for 4 weeks, then once every 1-2 weeks for maintenance) or selenium sulphide shampoo (twice a week for 2 weeks [contraindicated in pregnancy]).

Face, ears, chest, and back

• Ketoconazole 2% cream (once or twice a day) or another imidazole cream (clotrimazole or miconazole) for at least 4 weeks. An antifungal shampoo such as ketoconazole 2% can be used as body wash.

If severe or widespread seborrhoeic dermatitis → refer

Question 7

Describe

Answer 7

Urticaria

Question 8

What is the difference between acute and chronic urticaria?

Answer 8

• Acute urticaria — symptoms last for less than 6 weeks.
• Chronic urticaria — symptoms persist for 6 weeks or longer, on a nearly daily basis.

Question 9

Describe the pathophysiology of urticaria. What can cause this?

Answer 9

The release of histamine and other inflammatory mediators (such as leukotrienes and prostaglandins) from activated mast cells results in the characteristic pruritus, vascular permeability (leading to plasma leakage from the capillary into the skin), and oedema

Acute urticaria causes:

• Foods - milk, eggs, peanuts, tree nuts and shellfish
• Insect bites and stings
• Contact allergens, such as latex
• Certain drugs

Chronic urticaria

• Can be spontaneous
• Autoimmune
• Chronic inducible urticaria (in response to a physical stimulus)
  
  • Aquagenic
  • Cholinergic
  • Cold
  • Heat
  • Delayed pressure

Question 10

What are typical features of urticaria?

Answer 10

• A central swelling of variable size (red or white in colour), almost invariably surrounded by an area of redness (flare).
• Associated itching or, sometimes, burning sensation.
• A fleeting nature, with the skin returning to its normal appearance, usually within 1–24 hours.

Question 11

How do we manage urticaria?

Answer 11

• If avoidable triggers are identified, given clear instructions on avoidance strategies. (if not symptoms dairy)
• mild - no tx
• Symptomatic - Non-sedating antihistamine e.g. cetrizine for up to 6 weeks
• If symptoms are severe, give a short course of an oral corticosteroid (for example prednisolone 40 mg daily for up to 7 days) in addition to the non-sedating oral antihistamine.

Question 12

Answer 12

Atopic dermatitis

Question 13

What is atopic eczema/dermatitis?

Answer 13

Atopic eczema (also known as atopic dermatitis) is a chronic inflammatory skin condition that affects people of all ages, although it most frequently presents in early childhood (mostly before 5 years of age).

Question 14

Describe the presentation of atopic eczema.

Answer 14

• Pruritic rash
• Usually starts in infancy and episodic
• Familial or personal hx of allergic rhinitis and asthma
• Adults - generalised dryness and itching with exposure to irritants
• Children and adults with long-standing disease - flexure of limbs
• In infants, eczema primarily involves the face, the scalp, and the extensor surfaces of the limbs. The nappy area is usually spared.

Question 15

How should we assess the severity of atopic eczema?

Answer 15

• Clear - normal skin and no evidence of eczema
• Mild - if there are areas of dry skin, and infrequent itching (with or without small areas of redness)
• Moderate - if there are areas of dry skin, frequent itching, and redness (with or without excoriation and localized skin thickening)
• Severe — if there are widespread areas of dry skin, incessant itching, and redness (with or without excoriation, extensive skin thickening, bleeding, oozing, cracking, and alteration of pigmentation)

Question 16

How do we manage mild atopic eczema?

Answer 16

• Advice
• Topical emollients
• Consider mild topical corticosteroid e.g. hydrocortisone 1% - continue for 48 hrs after the flare up

Question 17

How do we manage moderate atopic eczema?

Answer 17

• Consider need for admission or referral (in infection)
• Advice
• Topical emollients
• Consider moderate topical corticosteroid e.g. betamethasone valerate 0.025% or clobetasone butyrate 0.05%- continue for 48 hrs after the flare up
• Occlusive dressings or dry bandages may be of benefit; however, treatment should only be started by a healthcare professional trained in their use
• If there is severe itch or urticaria, consider prescribing a one-month trial of a non-sedating antihistamine (such as cetirizine, loratadine, or fexofenadine).
• Prescribe preventative treatment according to the usual severity of the condition between flares.
  
  • Consider prescribing a maintenance regimen of topical corticosteroids to control areas of skin prone to frequent flares

Question 18

How do we manage moderate severe eczema?

Answer 18

• Consider the need for immediate admission or referral - e.g. for infection
• Advice
• Emollients
• If the skin is inflamed, prescribe a potent topical corticosteroid (for example betamethasone valerate 0.1%) to be used on inflamed areas.
• If there is severe itch or urticaria, consider prescribing a one-month trial of a non-sedating antihistamine (such as cetirizine, loratadine, or fexofenadine).
• If itching is severe and affecting sleep, consider prescribing a short course (maximum of two weeks) of a sedating antihistamine (such as chlorphenamine).
• If there is severe, extensive eczema causing psychological distress, consider prescribing a short course of an oral corticosteroid (refer children under 16 years of age).
• Prescribe preventative treatment according to the usual severity of the condition between flares.
  
  • Consider prescribing a maintenance regimen of topical corticosteroids to control areas of skin prone to frequent flares
• Refer urgently (within 2 weeks) to dermatology if eczema is severe and has not responded to optimum topical treatment after 1 week.

Question 19

What is contact dermatitis?

Answer 19

Contact dermatitis is an inflammatory skin condition which occurs as a result of exposure to an external irritant or allergen.

Question 20

What is the difference between allergic and irritant contact dermatitis?

Answer 20

• Allergic contact dermatitis is a type IV (delayed) hypersensitivity reaction that occurs after sensitization and subsequent re-exposure to a specific allergen or allergens.
• Irritant contact dermatitis is a non-immunological inflammatory reaction caused by the direct physical or toxic effects of an irritating substance on the skin — prior sensitisation is not required.

Question 21

What are common allergens and irritants?

Answer 21

• Common allergens include:
  
  • Personal care products such as cosmetics, skin care products, nail varnish, fragrances, sun screen and hair dye.
  • Metals such as nickel and cobalt (often found in jewellery) and chromate (in cement) – nickel is the most common allergen.
  • Topical medications including anti-infective agents and topical corticosteroids.
  • Rubber additives (often found in footware).
  • Plants – compositae group (chrysanthemum and sunflowers), daffodils, tulips, and primula are the most common.
• Common irritants include:
  
  • Water, in particular repeated or prolonged contact, such as with wet working conditions.
  • Sweating under occlusion.
  • Detergents, soaps and cleaning agents.
  • Solvents and abrasives.
  • Machine and cutting oils.
  • Acids and alkalis (including cement).
  • Reducing agents and oxidizing agents (including sodium hypochlorite).
  • Powders, dust and soil (such as exotic woods and cement).
  • Certain plants such as ranunculus, spurge, boracinaceae and mustards.

Question 22

What are the clinical features of irritant contact dermatitis?

Answer 22

• Hx of strong irritants (such as strong acids or alkalis) can cause immediate reactions whereas mild irritants usually require prolonged or repeated exposure before a reaction becomes apparent.
• Symptoms and signs: stinging, smarting, burning, dryness, tightness and chapping — vesicles are less commonly seen than in allergic contact dermatitis.
• Anatomical distribution may aid diagnosis, for example, dermatitis in the webs of fingers/underneath a ring in someone repeatedly exposed to water or detergents is suggestive of irritant contact dermatitis.
• Avoidance of the causative agent usually leads to resolution of symptoms within a few days.

Question 23

What are the clinical features of allergic contact dermatitis?

Answer 23

• Clinical reactions usually develop 24–72 hours (or longer in some cases) after re-exposure to an allergen in a sensitized person.
• The dominant symptom is usually itching.
• In acute and severe cases blistering, weeping and/or oedema may develop.
• Dermatitis may affect areas not directly in contact with the allergen, for example, due to transfer of nail varnish from the finger tips to the eyelids.
• Resolution can take many days, with or without treatment.

Question 24

What is the gold standard investigation for contact dermatitis?

Answer 24

patch testing

Question 25

How do we manage contact dermatitis?

Answer 25

If causative agent identified: * Avoidance of stimulus * 8-12 weeks may be needed before improvement seen * Liberal emollient use and soap substitutes (stay away from fire) * Consider need for topical steroids * Consider referral

Question 26

Answer 26

Discoid eczema

Question 27

What are the causes of discoid eczema?

Answer 27

Some cases are associated with [*Staphylococcus aureus*](https://dermnetnz.org/topics/staphylococcal-skin-infection) infection. The eruption can be precipitated by: * A localised injury such as scratch, [insect bite](https://dermnetnz.org/topics/arthropod-bites-and-stings) or [thermal burn](https://dermnetnz.org/topics/thermal-burn) * [Impetigo](https://dermnetnz.org/topics/impetigo) or [wound infection](https://dermnetnz.org/topics/wound-infections) * [Contact dermatitis](https://dermnetnz.org/topics/contact-dermatitis) * [Dry skin](https://dermnetnz.org/topics/dry-skin) * [Varicose veins](https://dermnetnz.org/topics/varicose-veins) (varicose eczema)

Question 28

Describe the clinical features of discoid eczema.

Answer 28

Discoid eczema usually affects the limbs, particularly the legs, but the rash may be widespread. Although often bilateral, the distribution can be asymmetrical especially if related to varicose veins. Well-defined, coin-shaped and coin-sized plaques of eczema Itchy

Question 29

What are the investigations for discoid eczema?

Answer 29

In most cases, the appearance of discoid eczema is quite characteristic. * Bacterial swabs may reveal [*Staphylococcus aureus*](https://dermnetnz.org/topics/staphylococcal-skin-infection) colonisation or infection. * Scrapings are commonly taken for [mycology](https://dermnetnz.org/topics/mycology-of-dermatophyte-infections), as discoid eczema can look very similar to [tinea corporis](https://dermnetnz.org/topics/tinea-corporis) (ringworm infection). * [Patch testing](https://dermnetnz.org/topics/patch-tests) should be considered in chronic discoid eczema as contact allergy to metals, such as nickel and chromate, have been commonly reported.

Question 30

How do we treat discoid eczema?

Answer 30

* **Protect the skin from injury.** This type of dermatitis often starts after minor skin injuries, so careful skin protection is required. * **Apply** **emollients** **frequently** * **Avoid** **allergens** * **Topical** **steroids** * **Antibiotics** [Antibiotics](https://dermnetnz.org/topics/antibiotics) (eg, [erythromycin](https://dermnetnz.org/topics/erythromycin), [flucloxacillin](https://dermnetnz.org/topics/penicillin)) * **Oral antihistamines**

Question 31

Answer 31

Vesicular hand dermatitis

Question 32

What is vesicular hand dermatitis ?

Answer 32

Vesicular hand dermatitis is a form of hand [eczema](https://dermnetnz.org/topics/hand-dermatitis) characterised by vesicles or bullae(blisters). A similar condition can affect the feet (vesicular foot dermatitis). The most common variant of vesicular hand dermatitis is also called vesicular endogenous eczema, dyshidrotic eczema, and pompholyx; cheiropompholyx affects the hands and pedopompholyx affects the feet.

Question 33

What are the causes of vesicular hand dermatitis?

Answer 33

In many cases, it appears to be related to sweating, as flares often occur during hot weather, humid conditions, or following an emotional upset. Other contributing factors include: * Genetics * [Contact with irritants](https://dermnetnz.org/topics/irritant-contact-dermatitis) such as water, detergents, solvents and friction * Association with [contact allergy to nickel](https://dermnetnz.org/topics/nickel-allergy) and other [allergens](https://dermnetnz.org/topics/contact-allergens) * Inflammatory dermatophyte ([tinea](https://dermnetnz.org/topics/tinea)) infections (when it is known as a [dermatophytid](https://dermnetnz.org/topics/dermatophytide-reactions)) * Adverse reaction to drugs, most often [immunoglobulin therapy](https://dermnetnz.org/topics/intravenous-immunoglobulin). Vesicles can also occur in other types of [hand dermatitis](https://dermnetnz.org/topics/hand-dermatitis).

Question 34

What are the clinical features of vesicular hand dermatitis?

Answer 34

Vesicular hand/foot dermatitis presents as recurrent crops of deep-seated blisters on the palms and soles. They cause intense itch or a burning sensation. The blisters peel off and the skin then appears red, dry and has painful fissures (cracks).

Question 35

How do we manage vesicular hand dermatitis?

Answer 35

**General measures:** * Wet dressings to dry up blisters, using dilute [potassium permanganate](https://dermnetnz.org/topics/potassium-permanganate), aluminium acetate or acetic acid * Cold packs * Soothing [emollient](https://dermnetnz.org/topics/emollients-and-moisturisers) lotions and creams * Potent [antiperspirants](https://dermnetnz.org/topics/antiperspirant) applied to palms and soles at night * Protective [gloves](https://dermnetnz.org/topics/gloves-for-hand-protection) should be worn for wet or dirty work * Well-fitting footwear, with 2 pairs of socks to absorb sweat and reduce friction. **Prescription medicines:** * Ultrapotent [topical corticosteroid creams](https://dermnetnz.org/topics/topical-steroid) applied to new blisters under occlusion, and ointments applied during the inflamed dry phase. * Short courses of [systemic corticosteroids](https://dermnetnz.org/topics/systemic-steroids), usually prednisone or prednisolone, may be prescribed for flare-ups. * Oral anti-staphylococcal [antibiotics](https://dermnetnz.org/topics/antibiotics) are prescribed for [secondary bacterial infection](https://dermnetnz.org/topics/wound-infections). * Topical and [oral antifungal agents](https://dermnetnz.org/topics/oral-antifungal-medication) are prescribed for confirmed [dermatophyte infection](https://dermnetnz.org/topics/tinea). * In patients with [hyperhidrosis](https://dermnetnz.org/topics/hyperhidrosis), an anticholinergic agent such as propantheline or oxybutynin may be worth trying. * In severe cases, [immune-modulating medicines](https://dermnetnz.org/topics/drug-induced-immunosuppression) are indicated. These include [methotrexate](https://dermnetnz.org/topics/methotrexate), [mycophenolate mofetil](https://dermnetnz.org/topics/mycophenolate-mofetil), [azathioprine](https://dermnetnz.org/topics/azathioprine-and-mercaptopurine) and [ciclosporin](https://dermnetnz.org/topics/ciclosporin).

Question 36

What is eczema herpeticum? How does it present?

Answer 36

Disseminated herpes simplex virus infection (eczema herpeticum) presents with widespread lesions that may coalesce into large, denuded, bleeding areas that can extend over the entire body, occasionally complicated by secondary infection with staphylococcal or streptococcal species. * Fever, lymphadenopathy, and malaise are common with eczema herpeticum

Question 37

What are the RFs for eczema herpeticum?

Answer 37

* early-onset and severe atopic eczema * marked elevations in total immunoglobulin E (IgE), * elevated allergen-specific IgE levels * peripheral eosinophilia * presence of [filaggrin](https://cks.nice.org.uk/topics/eczema-atopic/background-information/causes/) mutations

Question 38

How should eczema herpeticum be managed?

Answer 38

Oral **aciclovir** If around eyes, refer to ophthalmologist (same day) Health education (emergency = rapidly worsening eczema, clustered blisters, punched-out erosions)

Question 39

How does infected eczema present? How should it be investigate and treated?

Answer 39

* Bacterial infection with *Staphylococcus aureus* may present as typical impetigo or as worsening of eczema (with increased redness, oozing, and crusting of the skin). Skin swab and culture Oral **flucloxacillin** (erythromycin if pen-allergic) ***N.B.*** ***eczema herpeticum*** ***looks similar to*** ***impetigo*** ***so treat for both empirically with oral/IV ABx and oral/IV aciclovir***

Question 40

Answer 40

thermal burn

Question 41

What is the difference between a complex and non-complex burn?

Answer 41

* Non-complex: * Any partial-thickness thermal burn covering less than or equal to 15% of the total body surface area (BSA) in adults, or less than or equal to 10% in children (less than or equal to 5% in children younger than one year of age), that does not affect a critical area * A deep partial-thickness burn covering less than or equal to 1% of the body. * Complex: * Any thermal burn injury affecting a critical area. * Critical areas are defined as burns to the face, hands, feet, perineum, or genitalia; burns crossing joints, and circumferential burns. * Any thermal burn covering more than 15% of the total BSA in adults or more than 10% in children (more than 5% in children younger than one year of age). * All chemical and electrical burns.

Question 42

How should you assess a burn?

Answer 42

* **Assess:** * The timing, type, and cause of the burn (for example flame, scald, contact burn, electrical, or chemical), and mechanism of injury. * possibility of NAI * Location, size, and extent of the burn → (burn severity) * Total burn surface area (TBSA) * Wallace's rule of nines: risk of overestimating burn * Arm — 9% * Head — 9% * Neck — 1% * Leg — 18% * Anterior trunk — 18% * Posterior trunk — 18% * The [Lund and Browder chart](https://www.goodfellowunit.org/sites/default/files/Burns/Lund_and_Browder_chart.pdf) — this is more accurate, and can be used in adults and children. * Burn depth

Question 43

When should you refer a burns injury?

Answer 43

* **Referral** criteria to secondary care: * [1] all full-thickness (3^rd degree) burns * [2] all deep dermal (partial thickness, 2^nd degree) burns * [3] superficial dermal (partial thickness, 2^nd degree) burns: * **≥3% TBSA (adult)** or **≥2% TBSA (child)** * Burns involving the… face, hands, feet, perineum, genitalia, any flexure, or circumferential burns of the limbs, torso, or neck * [4] chemical burns, electrical burns, inhalational injury alongside burns

Question 44

How should you manage a burns injury?

Answer 44

* **Fluid resuscitation** (Parkland’s formula; 14/16G cannulae in each ACF – _even if through a burn site_) * **Parkland** formula = **4** **(mL)** x **weight (kg)** x **% burn** = mL Hartmann’s in first 24 hours (50% in 1^st 8 hours) * I.E. 70kg adult with 23% burns = 4 x 70 x 23 = 6,440mL (3,220mL in first 8 hours) * For… _children ≥10%_ burn, _adult ≥15%_ burn * This is **_only a guide_**! Monitor fluid status and UO – beware ‘fluid creep’ of over-filling * **Crystalloid** (i.e. Hartmann’s) * **Dressings**, **“Cool the burn, warm the patient”** (ensure clotting cascade (F9 to F10) not inhibited): * Temporary: saline gauze, paraffin gauze, clingfilm * Definitive: * **Partial thickness**: biological, synthetic, silver sulfadiazine cream ± cerium nitrate * **Full thickness**: early excision and split-skin graft * **Escharotomy** (removal of tough leathery-like eschar following rehydration of burned skin which **when left** can contribute to impaired circulation and a burn-induced compartment syndrome – i.e. in torso burns)

Question 45

What is onychomycosis? What causes it? What are the RFs?

Answer 45

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 Risk factors include for fungal nail infections include diabetes mellitus and increasing age.

Question 46

How do we investigate onychomycosis?

Answer 46

* 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

Question 47

How do we manage onychomycosis caused by dermatophytes?

Answer 47

* 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

Question 48

How do we manage onychomycosis caused by candida?

Answer 48

* 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 * *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