Allergic & drug reactions + miscellaneous skin conditions

Question 1

Contact dermatitis / atopic eczema - What is it? Caused by what?

Answer 1

• Inflammation of the skin caused by irritants and allergens

• Irritants. Eg detergent and strip the natural oils. ➤ Irritant contact dermatitis.
• Allergens ➤ immune system develops specific reaction. Eg: nickel

Question 2

Contact dermatitis / atopic eczema - Characterised by?

Answer 2

Characterised by erythematous and pruritic skin lesions

Question 3

Contact dermatitis / atopic eczema - in who?

Answer 3

Often occupational in adults

Question 4

Contact dermatitis / atopic eczema - linked to?

Answer 4

• Complex and multifactorial ➤ recent research suggest barrier dysfunction ➤ filaggrin mutations have been implicated
• Linked to other allergic disorders- asthma, rhinitis

Question 5

Contact dermatitis / atopic eczema - Ix

Answer 5

Patch testing

Question 6

Contact dermatitis / atopic eczema - characteristics

Answer 6

Erythema with scaling and well defined border

Question 7

Atopic eczema - What is it?

Answer 7

Atopic eczema (atopic dermatitis) is a chronic inflammatory itchy skin condition that develops in early childhood in the majority of cases.

Question 8

Atopic eczema - Caused by?

Answer 8

A genetic component that leads to the breakdown of the skin barrier. This makes the skin susceptible to trigger factors, including irritants and allergens, which can make the eczema worse.

Question 9

Contact dermatitis / atopic eczema - Tx

Answer 9

o Maintenance of skin care
o Topical anti-inflammatory meds
o Itch control
o Manage triggers
o Emollients eg E45, should contain no active ingredients eg urea or lanolin
o TCS most available over the counter
o Oral anti histamines- not recommended only for short term relief
o Oral corticosteroids and antibiotics ➤ prescribed

Question 10

Irritant contact - Characteristics?

Answer 10

• Usually the hands
• Burning, pruritus, pain
• Dry and fissured skin
• Lesion borders Less distinct borders

Question 11

Allergic contact - Characteristics?

Answer 11

• Usually exposed areas of skin, often the hands
• Pruritus is the dominant symptoms
• Vesicles and bullae
• Distinct angles, lines and borders

Question 12

Atopic eczema in children - Dx

Answer 12

o Visible flexural dermatitis involving skin creases or on cheeks or extensor areas in children aged 18 months or under
o Hx of flexural dermatitis
o Hx of dry skin last 12 months
o Hx asthma or allergic rhinitis
o African, black Caribbean, Asian, atopic eczema is on extensor surfaces rather than flexures and circular or follicular

Question 13

Atopic eczema in children - Triggers

Answer 13

o	Irritants soaps detergents 
o	Skin infections 
o	Contact allergens 
o	food allergens 
o	Inhalant allergens

Question 14

Atopic eczema in children - Tx

Answer 14

o Mild atopic eczema: emollients, mild potent TCS (topical corticosteroids)
o Moderate atopic eczema: emollients, moderate potent TCS, topical calcineurin inhibitors, bandages
o Severe atopic eczema: emollients, potent TCS, topical calcineurin inhibitors, bandages, phototherapy, systemic therapy

Question 15

Cutaneous drug reaction - Characteristics

Answer 15

• Immunological (drug allergy) OR non-immunological (drug tolerance) ➤ <10% drug allergies.
• USA 15,438 in patients, 346 patients had 358 drug skin reactions reaction rate 2.2%
• Rashes attributed to 51 drugs: amoxicillin (51 reactions per 1000), trimethoprim (34 per 1000), ampicillin (34 per 1000)
• More susceptible to drug reaction ➤ EBV, CMV infection, HIV, specific HLA antigen polymorphisms and ampicillin/amoxicillin sensitivity
• Type A: side effects ➤ allergy predictable
• Type B: hypersensitivity reactions often immune mediated and reproducible with repeated exposure

Question 16

Cheloid scar - Associated with?

Answer 16

Genetic

Question 17

Hypertrophic scar - Characteristics

Answer 17

Overproduction of collagen
(Burns associated with hypertrophic scar)
Some people are more prone to it
No treatment, you can try to excise them
A problem with children ➤ child grow but the scar doesn’t grow (they try to put children with scars with compressive garment). Children are more prone to really bad with scaring ➤ pathological scarring.

Question 18

Chronic wounds

Answer 18

More in the elderly
Caused by poor circulation (systemic disease, long term steroid, diabetes…).
As you get older, some wounds don’t want to heal – no one knows why
May cause amputation of the limbs

Question 19

Peripheral vascular disease

Answer 19

Might be asymptomatic
They might get pain on walking
Weird areas on the skin that are abnormal  dry skin, redness
Might lose their hair

Question 20

Hidradenitis suppurativa - Characteristics

Answer 20

• Quite rare
• Chronic condition of the sweat glands
• Sweat glands become clogged due to a variety of reasons= dilatation and infection
• Chronic = scarring
• Common in women
• Often associated with hair removal, deodorants, and irritation from anything rubbing against the affected area can worsen the condition.
• Associated with smoking, obesity, genetic as runs in families

• Treatment:
o Weight loss
o Long term Rx with antibiotics, steroids in severe cases immunosuppressant drugs
o Also surgery

Question 21

Diabetic foot - Characteristics

Answer 21

• Caused by friction, trauma, diabetes
• Neuropathy associated with diabetes
• GP
• Manage blood sugar
• Stop smoking
• Maintain healthy BMI
• May require debridement
• Specialised wound care
• Risk of amputation is 15 to 46 times higher in diabetics
• 90% all foot and lower limb amputations associated with diabetes

•	Prevention: 
o	Good foot care
o	Check feet regularly 
o	Good blood sugar control 
o	Stop smoking