Week 2 Flashcards
What are the chemical mediators that causes pruritus
PGE2
IL2
Histamine
Substance P
Acetylcholine
What type of nerve transmits the sense of pruritus to the brain
Unmyelinated C fibres
Describe the synergism between PGE2 and histamine
PGE2 reduces the threshold of human skin to histamine evoked itching
Different causes of pruritus
Pruriceptive
Neuropathic
Neurogeic
Psychogenic
What mediates neurogenic cause of itch
Opiates (exogenous or endogenous)
What is pruritoceptive cause of pruritus
When something in the skin that triggers the itch e.g. inflammation / dryness
What is neuropathic cause of pruritus
Damage to central or peripheral nerves causing itch
What is psychogenic cause of pruritus
Psychological causes with no CNS damage
Presentation of acne vulgaris
Non-inflammatory lesions: comedones (open or closed)
Inflammatory lesions: papules, nodules, pustules
Cysts
Scarring
Erythema
Difference between papules and pustules
Papules are solid raised bumps that are not pus filled whereas pustules are
Difference between pustules and cysts
Cysts = multiple pustules joined together to form a larger pus filled cyst
What are open comedones
Blackheads
What are closed comedones
White heads
Cause of acne vulgaris
Increase in sebum production / hyperplasia of sebaceous glands causing occlusion of pores allowing bacterial colonisation hence causing inflammation
What causes hyperplasia of sebaceous glands
Increase in androgens
What is considered as mild acne
Scattered papules, pustules and comedones
What is considered as moderate acne
Numerous papules, pustules
mild atrophic scarring
What is considered as severe acne
extensive inflammatory lesions including nodules, cysts
Significant atrophic scarring
Example of atrophic scarring
Ice pick scarring - small indentations on the skin due to acne
Why does acne mostly appear during puberty
Because during puberty, there is an increase in androgen. Increase in androgens then cause increase in sebum and hyperplasia of sebaceous glands
Describe the distribution of acne vulgaris
Reflects sebaceous glands sites
- face
- back
- chest
Management for mild acne
Topical benzoyl peroxide + topical clindamycin
Or
topical benzoyl peroxide + topical adapalene
Or
Clindamycin + tetrinoin
Management for moderate acne vulgaris
Topical benzoyl peroxide + topical adapalene / Clindamycin + topical tetrinoin / topical benzoyl peroxide + topical clindamycin
Or
Azelaic acid + oral tetracycline
Or
Oral anti-androgen
Examples of topical retinoids
adapalene
isotretinoin
tretinoin
What effect does topical retinoid have on the skin
Drying effect which removes excess sebum
What effect does topical benzoyl peroxide have on the skin
Keratolytic (keratin builds up in acne)
Antibacterial
What are the oral antibiotics used for acne vulgaris
Tetracyclines: doxycycline, Lymecycline
Contraindications for tetracyclines
Pregnancy
Breastfeeding
What are the oral anti-androgens that females can take to treat moderate acne
Oral contraceptive pill
Spironolactone
Why are oral anti-androgens not used in males
Due to feminising effects
Management for severe acne
Oral isotretinoin
What should patients be aware of when taking oral isotretinoin
There will be an initial aggravation of acne before it gets better
Contraindications for oral retinoids
Pregnancy
Liver impairment
Side effects of oral retinoids
Dry mucous membranes
Hair thinning
Hair loss
Headaches
What 2 things should be monitored when taking oral retinoids and why
LFT due to risk of hepatitis
Any changes in mood due to risk of depression
What is rosacea
chronic skin condition causing flushing of the forehead, nose, cheeks and chin
Rosacea is more common in females / males
Females
Rosacea most commonly affects which age group
30-60 years old
Presentation of Rosacea
Facial flushing
Rash
- Erythema
- Papules and pustules
- telangiectasia
- Rhinophyma
What is rhinophyma
Enlarged red nose, a bulb shape
Facial flushing in rosacea can be exacerbated by
Increase in temperature
Alcohol
Spicy foods
Sun exposure
Warm baths
Difference between rosacea and acne
Rosacea is not due to inflammation in pilosebaceous unit
Rosacea does not have comedones
Management for rosacea
Avoid triggers
Use sun protection creams
1. Topical treatment (brimonidine / metronidazole)
2. Oral therapies (tetracycline / isotretinoin if severe)
Laser therapy (for persistent telangiectasia)
Surgery (for rhinophyma)
Describe the topical therapies for rosacea
Topical brimonidine or Ivermectin
Topical metronidazole (antibiotic)
Describe the oral therapies for rosacea
Oral tetracycline
Low dose oral isotretinoin for severe rosacea
Rosacea increases risk for infestation of which organism
Demodex mites infestation at eyelashes
Laser therapy for rosacea is indicated when
Patient has persistent telangiectasia
Complications of rosacea
Rhinophyma
Ocular involvement - conjunctivitis, blepharitis (Gritty eyes)
What are lichen disorders
Conditions characterised by damage to basal epidermis
Differences between lichen planus and psoriasis
Psoriasis is scaly whereas lichen planus isn’t
Psoriasis doesn’t involve the oral cavity whereas lichen planus does
What are the 6 Ps that characterise lesions of lichen planus
very Pruritic
Polygonal
Purple
Planar (flat topped)
Papules or Plaques
Symptoms of lichen planus
6Ps
Very itchy
Oral involvement
Wickham’s striae
Longitudinal ridging of the nails
How does lichen planus affect the mouth
Mucosal ulceration
Wickham’s striae inside of the mouth
What is Wickham’s striae
Lacy white lesions
Oral candida also causes white lesions. How can you differentiate it from Wickham’s lesions in Lichen Planus
The white lesion in Lichen Planus cannot be wiped off
Describe the distribution of lesions in Lichen planus
Flexural distribution - wrists, ankles
Legs
Histological features of lichen planus
Irregular sawtooth acanthosis
Cytoid bodies
Inflammatory cells infiltrate at upper dermis
Orthohyperkeratosis
What is orthohyperkeratosis
Thickening of stratum corneum (outermost layer) with non-nucleated keratinocytes
so this is not parakeratosis because parakeratosis involves retaining the nuclei
Management for Lichen planus
Emollients
Topical steroid
PUVA / UVB phototherapy
Oral steroids if lesions do not resolve after 12 months
What is lichenoid eruption
Lichenoid disorder due to medication