Dermatology Flashcards
Where is the most common site of keloid scar formation?
Sternum (other common sites = shoulders, neck + face, extensor surfaces of limbs)
What is the typical presentation of acne rosacea?
Commonly transient erythema initially, progressing into erythematous rash of papules and pustules and telangiectasia involving nose and cheeks, may progress into rhinophyma in late stage.
What are the different layers in the structure of the skin?
Epidermis (avascular, 4 x layers : corneum, granulosum , spinosum and basale. 3x main cells: keratinocytes (secrete extracellular proteins and lipids and store the melanin), melanocytes (neural crest derived cells that produce melanin and migrate to the skin at the end of the 1st trimester) and langerhan cells (the immune cells of the skin).
Dermis (vascular. Extracellular matrix of collagen and elastin secreted by fibroblast cells. Mast cells are the immune cells of the dermis)
What is the common presentation of livedo reticularis?
A purple lace like, non-blanching rash often on the legs caused by swollen venules. Commonly seen in the elderly and exacerbated by the cold, association with SLE.
Treatment of acne rosacea?
1st advise on avoiding triggers (food diary, avoid UV etc)
1st line topical treatment for erythema = topical brimonidine 0.5% gel OD for temporary relief of redness onset within 30 mins and lasting around 3-6 hours).
For papules / pustules = topical ivermectin (a topical insecticide) OD for 8-12 week course. Topical metronidazole or azelaic acid can be used for papulopustular rosacea if ivermectin contraindicated eg pregnancy. If severe / limited improvement, can add course of oral doxycycline
What is the classical presentation of pretibial myxoedema?
Symmetrical erythematous rash over shins with ‘orange peel’ texture seen in Grave’s disease (antibodies to TSH receptor which active release of thyroid hormones = hyperthyroidism).
What is the typical presentation of erythema nodosum and what are some of the most common causes?
RAPID onset TENDER red nodules all over the shins.
A hypersensitivity reaction as a result of either:
* Drugs - penicillin antibiotics, sulfasalazine or COCP
* Acute bacterial or viral infection
* Inflammatory bowel disease
What are the 2 main categories of alopecia?
Scarring (destruction of the hair follicle) and non-scarring (preservation of the hair follicle)
What are common causes of scarring alopecia?
- discoid lupus
- lichen planus
- trauma / burns
- radiotherapy
- tinea capitis (ringworm of the scalp - caused by trichophyton and microsporum dermatophyte species)
What are common causes of non-scarring alopecia?
- Drugs - carbimazole, heparin, COCP, colchicine
- Iron deficiency
- Zinc deficiency
- Alopecia areata (an autoimmune condition)
- Telogen effluvium = hair loss after a stressful period
What is the Fitzpatrick system?
Grades the way your skin responds to the sun.
Fitzpatrick grade I = very fair, always burns never turns, typically freckly / ginger etc
Fitzpatrick grade V = very brown or black
Which skin conditions are associated with diabetes mellitus?
- Necrobiosis lipoidica (painless shiny area of yellowy/brown skin typically on the shin)
- ^ risk of infection (candida, staph)
- Vitiligo (patches of depigmented skin due to loss of melanin)
- Lipoatrophy (localised loss of fat tissue leading to dimpling in the skin -> associated with autoimmune conditions but also with the repeated subcut injections of insulin)
How should capillary haemangiomas be managed?
They may be present at birth or develop within the first 6 months of life.
~ 80% of haemangiomas stop growing by 5 months then they plateau then they shrink. The majority resolve by 10 years of age.
Haemangioms near the eye need close monitoring.
If they begin to affect vision / don’t resolve - PROPRANOLOL is 1st line treatment. If this fails, can try laser therapy or systemic steroids.
What is the first line treatment for psoriasis of the trunk + limbs
1) Potent topical corticosteroid + either oral vitamin D or topical vitamin D applied separately to the steroid (ie one in the morn and one in the eve) for upto 4 weeks, max 8 wks
2) if steroid + vit D fails after 8 wks -> vit D BD
3) If BD vit D fails -> BD topical steroid OR topical coal tar OR OD calcipotriol (vit D) + betamethasone cream for upto 4 wks
4) if all else fails
- > VERY potent topical steroid under specialist supervision
- > phototherapy = NARROW BAND UV B
- > photochemotherapy = PUVA = Psoralen + UVA
- > systemic therapies -> Methotrexate 1st line oral agent in psoriasis. other options = retinoids, ciclosporin, infliximab
What is the 1st line treatment for scalp psorasis?
1) Topical corticosteroid OD for upto 4 wks
2) if no improvement, consider pre-steroid exfoliant / salicylic acid or a different preparation of the steroid eg a shampoo
3) If no improvement then = calcipitriol + betamethasone OR vitamin D
4) -> very potent steroid for upto 2 wks OR coal tar -> if these fail then refer to specialist.
What is the 1st line treatment for facial / flexure or genital psoriasis?
Mild/moderate steroid for max 2 wks
Can vitamin D analogues for psoriasis be used in pregnancy?
NO - vit D analogues should be avoided in pregnancy
Typical presentation of lichen planus?
Itchy raised flat-topped lesions on the flexor surfaces / palms (have fine white lines on the surface = Wickham’s striae)
May have associated oral lichen planus = lacy white pattern in the mouth