Dermatology Flashcards
What are the 3 layers of the epidermis? (outer layer to inner)
Stratum corneum
Stratum granulosum
Basal Layer
What are the functions of the skin?
Protection from the environment (chemical, thermal, physical, UV) Thermoregulation Neuroreceptor (external stimuli) Antigen processing (Langerhan's cells) Synthesis of vitamin D Cosmetic
What history taking would you take in a patient with a skin disorder? (8)
Age,sex, occupation History of presenting complaint Relevant systems review Current/past treatment Past MH family history Drug history Allergies
What 3 things do you note when examining a skin condition?
- SITE: is it localised/generalised, distribution skin and/or mucosal membranes
- MORPHOLOGY: mono/polymorphic, blister/erosion/scarring
- BACKGROUND SKIN: normal/erythema (redness)
What is a macule?
<1cm.
It is a flat, circumscribed lesion on the skin which are not palpable.
They may be pigmented, red or non-pigmented.
What is a patch?
> 1cm flat, circumscribed lesion on skin that is not palpable.
They may be pigmented, red or non-pigmented.
What is a plaque (in terms of dermatology)?
> 1cm in diameter - Slightly raised, flat topped lesion
What is a papule?
Circumscribed
Palpable
Elevated
<1cm
May be itchy
What is a nodule?
Palpable elevation >1cm
What colour must you look out for in lesions which may indicate that a rapid referral is required?
If a lesion is brown/black - or if a lesion that is irregular in colour has some brown/black in it. May be malignant or on it’s way to becoming malignant
What is scale?
Peeling of stratum corneum/superficial epidermis.
Due to dryness of skin, lack of skin barrier
Will be itchy as skin is dehydrated
What do you call a small blister?
Vesicle (<0.5cm in diameter)
What is it called when skin becomes thick and leathery (e.g. from scratching)?
Lichenification
What do you call it when there is “a shallow breach in the surface from scratching often with a hemorrhagic crust?”
Excoriation
What do you call a blister that is more than 0.5cm in diameter?
Bulla
What would you call a full thickness loss of epidermis?
Ulcer
What is a scar?
It is a permanent change in skin surface/texture
What tests could you order to help diagnose a condition?
- Skin swabs/scrapings - bacteriology, virology, mycology
- Skin biopsy - histology, culture, immunofluorescence
- Patch tests - undertaken if a contact allergy is suspected
- Photo-tests - investigate a possible sensitivity to UV
What skin condition is a pruritic inflammatory condition associated with dryness and erythema of skin and scratching this results in excoriation and lichenification?
Eczema
Name 3 sub-types of eczema
Atopic/flexural
Varicose (lower legs, venous incompetence)
Seborrhoeic (centre of face usually)
Discoid (coin-shaped lesions)
Lichen simplex (thickened, dry scaly skin)
What 2 environmental factors mat also cause dermatitis?
IRRITANT contact: e.g over hand washing
ALLERGIC contact: sites that had direct contact with allergen.
In what type of patients would you typically find allergic contact dermatitis?
Patients with type 4 (delayed) hypersensitivity to a specific allergen
What microorganisms may secondarily infect eczema?
S. Aureus - impetiginised eczema: yellow crust and weeping
Herpes simplex - eczema herpeticum: monomorphic lesions
What would you advise patients with eczema to avoid?
Soap, shower gel and contact with irritants (e.g. domestic cleaning agents)
What would you advise patients with eczema to use?
Use gloves if cleaning
Emollients (e.g. soap substitute and moisturisers)
Topical steroids
Oral antibiotics
Antihistamines (sedative, especially over night)
Wet wraps
Acyclovir (anti viral) if suspect herpes simplex
What % of the population presents with psoriasis?
2%
What are the main characteristics of psoriasis? (4)
- Strong family history in most cases
- Symmetrical well-defined red plaques with tick silvery scale
- Elbows and knees are common sites
- Lasts for many years
Name the 4 types of psoriasis
Psoriasis vulgaris
Guttate
Erythrodermic
Pustular
What does psorasis vulgaris look like?
Chronic plaque psoriasis.
Well-defined salmon pink plaques with silvery scale
Where on the body is frequently affected by psoriasis?
Where can also be affected?
Scalp and hairline
Nails - nails can have pits and under the nails can be affected (subungual) hyperkeratosis - plaque can form under nails
Describe guttate psoriasis
It involves raindrop size lesions and often follows a streptococcal throat infection
Which type of psoriasis often requires hospital treatment?
Pustular
How could you treat psoriasis? (7)
- Emollients/bath oils
- Vitamin D analogues (e.g. calcipotriol [steroid])
- Tar preparations
- Topical steroids
- Dithranol
- UVB, PUVA (PUVA is when you take the drug PSORALEN and then expose the skin to UVA)
- Systemic (acitretin, methotrexate (Immunosuppressant), cyclosporin (immunosuppressant), biologics (immunosuppressant) )
What is the aetiology of Lichen Planus?
TRICK QUESTION
it has an unknown aetiology
What percentage of the population is affected by Lichen Planus?
1-2%
What is the onset of Lichen Planus?
30-60 years old
What does Lichen planus look like?
Flat-topped violaceous (violet colour) papules on skin
Name 3 clinical variants of Lichen Planus (out of 7)
Hypertrophic (thick plaque) Annular (ring-like lesions) Plantar (palm and soles) Oral (several subtypes) Lip Genital Scalp (lichen planopilaris)
What type of oral lichen planus presents as lacy white lesion pattern on mucosal tissues?
Reticular LP
What topical treatments can be used to treat lichen planus?
Emollients Topical steroids (check candida count orally as this can be a secondary infection)
What systemic treatments can be used for lichen planus?
Prednisolone (steroid)
Azathioprine/mycophenolate (immunosuppressants)
Methotrexate
What is pruritis?
Itching
Name 4 potential causes of itchy skin (pruritis) (9)
Xerosis (dry skin) Dietary (e.g iron deficiency anaemia) Endocrine (thyroid disorder) Inflammatory (eczema) Autoimmune (lichen planus) Infective (chicken pox) Infestation (e.g. scabies) Parasitic (e.g. cutaneous larva migrans) Neoplastic (e.g. lymphoma)
Which 2 conditions are caused by varicella?
Chicken pox
Shingles
Name 3 conditions that are caused by bacterial infections.
What bacteria is the most common cause for these?
Impetigo, cellulitis, paronychia (nail cuticles)
Staph aureus, strep infections
