Derm Rashes, Pruritius, Infections

Question 1

List 4 causes of Itchy skin

Answer 1

1. Primary rashes, e.g. eczema or psoriasis
2. Infections/ Infestations ( lice/ scabies)
3. Metabolic disorders ( uraemia, hyperbilirubinemia)
4. Medication related
5. Psycho/ social
6. Unknown cause

Question 2

List 3 most common causes of Rashes in the Elderly

Answer 2

20% dermatosis

30% have metabolic causes

50% are idiopathic

Question 3

Most common type of primary rash?

List 3 others in order of how common each is

Answer 3

Eczema = most common; atopic, irritant, gravitational, asteatotic or discoid

Psoriasis, urticaria, fungal infections, scabies

Question 4

List 2 rare causes of rashes

Answer 4

1. Bullous pemphigoid, pemphigus
2. Dermatitis herpetiformis; related to a gluten sensitivity
3. Lichen planus
4. Cutaneous lymphoma

Question 5

List some key questions you should ask when taking a history of a rash

Answer 5

Question 6

List some other rahses which are itchy

Answer 6

1. Psoriasis
2. Scabies
3. Pityriasis Rosea and Versicolor
4. Drug rashes; ask when did they start the medication?
5. Urticaria

Question 7

What is Pityriasis Rosea?

What is it a impt ddx for?

Answer 7

Viral infection by Parvovirus B19 which causes a widespread rash which normally starts on the upper torso → can move onto the legs and arms

Differential for guttate psoriasis

Not contagious, usually seen in younger patients

Question 8

Describe the rash and its progression seen in Pityriasis Rosea?

Answer 8

Rash is ALWAYS proceeded by a Herald Patch → then proceeds to the rest of the eruption

Appears as small tear-shaped, ovoid erythematous, raised, rough feeling eruptions, can be very itchy and widespread

Question 9

What advice should we give patients with Pityriasis Rosea?

Answer 9

Patients are understandably distressed, therefore always REASSURE them that it is a self-limiting condition and that there is not much that can be done

Normally last about 6-8 weeks

Question 10

Management of Pityriasis Rosea

Answer 10

Supportive treatments: emollients+ topical steroids if itchy + anti-histamines if persistently itchy

Question 11

What is Pityriasis vesicolour?

Answer 11

Rash caused by Malassezia furfur (yeast) type infection

Causes a discoloration of the skin+ hypo or hyperpigmentation of the skin

Asymptomatic

Question 12

Describe the rash seen in Pityriasis vesicolour

Answer 12

Appears as: tan and pale coloured well circumscribed patches/ macules

Bran like surface, fine scale, fairly symmetrical (one of the few infective causes of a rash which IS symmetrical)

Can cause itchiness

Question 13

Pityriasis vesicolour is often misdiagnosed as Vitiligo, list 3 differences between these

Answer 13

1. Hypopigmentation in Versicolor is LESS WELL-DEFINED than Vitiligo
2. Vitiligo has more well-defined borders
3. Pityriasis = fungal treatment, Vitiligo = steroid treatment

Question 14

List 4 common cause of drug rashes

Answer 14

1. Asprin → flushes, itchiness, rashes
2. NSAIDs
3. Penicillans
4. Allopurinol

Question 15

Will stopping the drug cause a drug rash to rapidly fade?

Answer 15

No the rash may persist for several days to weeks after you discontinue the medication, then it fades.

Usually, the rash disappears from the top of the body first and the legs and feet last.

Question 16

How soon within starting the drug does a penicillin rash come on?

Answer 16

Signs and symptoms of penicillin allergy often occur within an hour after taking the drug.

Less commonly, reactions can occur hours, days or weeks later.

Question 17

List 4 drugs unlikley to cause skin rashes

Answer 17

Question 18

What is Morbilliform Drug Eruption?

Answer 18

Type of allergic rxn triggered by drug eg. delayed reaction with penicillins

Most common form of drug eruption

Can see a widespread centrally confined, symmetrical, maculo-papular eruption

Question 19

What is the average interval between taking a new drug and onset of a rash?

Answer 19

Unless the patient has been previously sensitised to a drug, interval between initiation of the therapy and the onset of reaction is rarely < 1wk or > 1month

Question 20

When during the course is a penicillan rash most likley to appear?

Answer 20

The first time it comes on, it is usually at END of the course or the week afterwards and gets worse

90% of patients who report a penicillin allergy are not allergic

Question 21

A penicillan rash may often mimic what?

Answer 21

A strep infection or a viral illness - will fade quickly

Question 22

A patient presents to you requiring Abx, they tell you their mother and sister both had penicillan allergies. Can you prescribe them a penicillan?

Answer 22

Yes, It is not a reason to withhold penicillin if someone in the family is allergic to penicillin

Question 23

Describe the appearance of a penicillan rash

Answer 23

flat, red patches on the skin accompanied by smaller, paler patches → “maculopapular rash.”

Question 24

What is Lichen Planus?

Answer 24

Rash that can affect different parts of your body, including inside your mouth

Cause unknown; sometimes related to medications (drug-related licheniform eruptions)

Question 25

Describe the rash seen in Lichen Planus

Answer 25

Rash eruption with multiple, monomorphic, violaceous type lesions May have white scaliness on top → Wickham’ striae

Question 26

Describe the progression Lichen Planus

Answer 26

1. Usually starts on distil limbs (wrists and ankles) → Intensely itchy and very painful 2. Progresses to multiple lesions all over the body in the widespread form Can ERUPT anywhere where there has been trauma (or can be spread by scratching)

Question 27

Treatment of inflammatory disease (eczema, psoriasis, lichen planus, infections etc.)

Answer 27

Topical therapies with sedative antihistamines for short periods only Topical corticosteroids and topical immunomodulators reduce inflammation, relieve itch and can be applied to broken skin

Question 28

List an example of a sedating and non-sedating anti-histamines

Answer 28

Sedating: Promethazine Non-sedating: Loratadine

Question 29

List 4 types of emolliants and locations where each is used/preffered

Answer 29

1. Lotions: scalp, other hairy areas, mild dryness on face, trunk and limbs 2. Creams: used when more emollience is required on these later areas 3. Ointments: drier, thicker, more scaly areas 4. Bath oil

Question 30

List 4 pieces of advice you can give to a patient about their itch

Answer 30

1. Correct low humidity 2. Avoid synthetic fabrics 3. Pare nails 4. Avoid excessive bathing and hot baths 5. Moiturisers (dermacol, contains 1% methanol) 6. Soap substitute

Question 31

What is Urticaria and how does it present?

Answer 31

Urticaria = Hives Rxn which causes raised, red weals of a dermal oedema which are well-defined, can be itchy Each weal may last a few minutes or several hours and may change shape

Question 32

Compare acute vs chronic Urticaria

Answer 32

Acute: * present for less than 6 weeks * usually self-limiting * commonly resolves within 24 hours but may last up to 6 weeks Chronic: * present for more than 6 weeks * autoimmunity is the most likely cause * do routine bloods to check for immunosupression Neither has long term health consequences other than anxiety and depression.

Question 33

Is Urticaria an allergy?

Answer 33

Most cases of urticaria are NOT due to allergy → Patch test will NOT help As it presents as an allergy type reaction, patients are often worried about anaphylaxis. Reassurance is key

Question 34

List 4 triggers for Urticaria

Answer 34

1. Recent illness 2. Contact with certain plants, animals, chemicals and latex 3. cold – ie. cold water or wind 4. rxn to medicine, insect bite or sting Often the urticaria is triggered by a viral illness or other life event and no obvious cause is found

Question 35

Investigations for Urticaria

Answer 35

Acute urticaria: Patient’s history and physical examination should direct any diagnostic studies Chronic/recurrent urticaria: worth doing the following below... But all are likely to be normal * FBC, CRP, ESR * TSH/ T4 * Thyroid antibodies * Anti TTG (gluten) antibodies * ANA

Question 36

What is the RAST Test

Answer 36

Radioallergosorbent test → tests for specific IgE antibodies to identify possible allergies Difficult to interpret and may not be relevant to the current problem i.e. a raised level grass pollen will be related to a patient’s hayfever not their urticaria Low levels of positives are common AND are usually not relevant.

Question 37

List 2 other Physical Urticaria

Answer 37

* Cholinergic Urticaria; happens when stressed * Solar urticaria; from sun exposure * Cold urticaria * Pressure urticaria; immediate or delayed; similar to Demographism * Contact Urticaria

Question 38

How do we treat Urticaria

Answer 38

Step 1: **non-sedating antihistamine daily + menthol** Step 2: If no improvement after 2 wks, **↑ dose of antihistamine** (4x standard is safe and effective) Step 3: if still a problem, can try Monteleukast (LRA; mast cell stabiliser) or adding an H2 antihistamine e.g Ranitidine (less evidene for this)

Question 39

Are steroids used in Urticaria?

Answer 39

Oral steroids are overused in urticaria A short course (5-7 days) can be helpful in severe ACUTE urticaria BUT there is evidence that oral steroids can prolong the course of chronic urticaria; getting rebound on stopping them.

Question 40

List 4 pieces of general advice about Urticaria

Answer 40

1. Reassurance that it is usually self-limitingand is not life-threatening 2. Avoid NSAIDs; Aspirin will make it worse 3. Avoid Alcohol; getting overtired and try to reduce stress 4. Wear loose fitting clothes (put less pressure on the skin) 5. Psychological stress can trigger or increase itching 6. Avoid known triggers e.g. spicy food

Question 41

What is Demographia?

Answer 41

A hypersensitivity reaction to trauma - exaggerated response to the firm stroking of the skin Affects 5% of the population, tends to present in young adults and can occur on its own or with spontaneous urticaria Symptoms are often worse when the patient is hot and can be triggered by minor pressure e.g. tight areas of clothing

Question 42

How is demographia treated?

Answer 42

Treatment as per spontaneous urticaria

Question 43

What is angiodema?

Answer 43

Swelling underneath the skin, usually a reaction to a trigger ie. medicine or allergy Deeper swelling to simple Urticaria

Question 44

Pathophysiology and features of angioedema Incl 2 common locations

Answer 44

Vasodilation and exudation of plasma into deeper tissues Swelling is generally non-pitting, nonpruritic and occurs on the mucosal surfaces of the respiratory tract and GI tract Seen on peri-orbital areas and in lips

Question 45

Is angioedema usually dangerous?

Answer 45

Rarely can be life threatening - Mostly mild and settle spontaneously

Question 46

What must we ask in a patient with angioedema and WHY?

Answer 46

Ask patient if they have had a voice change Hoarseness is earliest sign of laryngeal oedema which be life threatening, can also get stridor and respiratory difficulties (rare)

Question 47

Treatment for severe reactions causing angioedema

Answer 47

Epipen and oral steroids