Dermatology Flashcards
Layers of epidermis from most superficial to deep
Stratum corneum Stratum lucidum Stratum granulosum Stratum spiniosum Stratum basale Dermis
Basement membrane between the dermis and epidermis
Keritanocytes gradually mature from the basal layer, keratinize, lose their nuclei and then shed
Functions of the skin
-Protection from the environment UV light, chemical, thermal and physical protection -Thermoregulation Shunting of blood and sweating -Neuroreceptor Sensory for external stimuli -Antigen processing Langerhan's cell -Synthesis of Vitamin D -Cosmetic?
Taking a history of a pt with skin disorder
-Age, sex, occupation
-Complains of
-History of presenting complaint
Site, spread, symptoms, pain, other involvements
-Relevant systems review
-Current/past tx
-Past and current med history
-Family history
-Drug/alcohol history
-Allergies
Examination of the skin disorder
- Examination should include careful complete skin inspection
- Look at hidden sites including the scalp, nails, umbilicus and natal cleft
- Mucous membranes like the oral mucosa, eyes, nasopharynx and genitalia
-Is the distribution: Localised/generalised Skin and/or mucous membranes Monomorphic (all look the same eg Herpes simplex) or polymorphic (rashes come out at different times so some are crusting and some are just arriving, meaning they all look different) Blister/erosion/scarring
-Background skin is normal/erythema
Common terms used to describe types skin lesions and their definitions
Macule- patch of skin that is well-circumscribed but not palpable and <1cm in diameter
Patch- patch of skin that is well-circumscribed but not palpable and >1cm in diameter
Papule- elevated, solid, palpable lesion that is <1cm in diameter
Plaque- slightly evelvated lesion >1cm in diameter
Nodule- palpable elevation that is >1cm in diameter
Vesicle- blister that is <0.5cm in diameter
Bulla- Blister that is >0.5cm in diameter, often filled with fluid
Scale- peeling of the stratum corneum/superficial epidermis
Ulcer- full thickness loss of epidermis
Scar- permanent change in skin surface/texture
Macule definition and example
- Patch of skin that is well circumscribed but not palpable
- <1cm in diameter
- eg. Freckle
Patch definition and example
- Patch of skin that is well circumscribed but not palpable
- > 1cm in diameter
- eg. Lentigo maligna
Papule definition and example
- Well circumscribed, palpable elevation
- <1cm in diameter
- eg. Lichen planus
- Often very itchy and associated with keratosis and ulcers orally
Plaque definition and example
- Slightly raised flat topped lesion
- > 1cm in diameter
- eg. chronic plaque psoriasis
- Characteristic salmon pink silver scaly plaque
- Often symmetrical so will appear on both sides of the body
Nodule definition and example
- Palpable elevation
- > 1cm in diameter
- eg. nodular malignant melanoma
Vesicle definition and example
- Blister
- <0.5cm in diameter
- eg. pompholyx eczema on the thenar eminence (palm)
Bulla definition and example
- Fluid-filled blister
- > 0.5cm in diameter
- eg. angina bullosa haemorrhagica- sudden appearance of blood blister shwen they eat a crusty piece of bread. Not serious and no tx needed
Scale definition and example
- Peeling of the stratum corneum
- Eg. severe eczema
Secondary changes to skin examples and definition
-Lichenification
Caused by chronic itching
Results in palpably thickened skin
Increased skin marking and lichenoid scale
Eg. chronic atopic eczema and lichen simplex
-Excoriation
Loss of epidermis and portion of dermis
If you scratch too much
May become infected if bacteria settles in
Lichenification and excoriation occurs in severe atopic eczema
Ulcer and scar may come under here??
Ulcer definition and example
- Full thickness loss of epidermis
- Ulcerated nodular basal cell carcinoma
Scar definition and example
- Permanent change in skin surface/texture
- eg. Lichen planus in the scalp which is just a bald patch
General, common investigations for skin diseases
The following tests are used to clarify or confirm a diagnosis:
-Skin swabs/scrapings
Bacteriology
Virology
Mycology (fungi)
-Skin biopsy
Histology
Culture
Immunofluorescence
-Patch tests
If a contact allergy is suspected
-Photo tests
To investigate a possible sensitivity to UV
If pt is unwell and either infected or in need of systemic therapy/treatment, the following blood investigations may also be required:
-Haematology
Full Blood Count
Erythrocyte Sedimentation Rate (ESR)
Important if introducing prednisone (glucocorticoid to supress immune system) or other immunosuppressive drugs
-Biochemistry
Urine and Electrolyte Test to detect abnormalities of blood chemistry
Liver Function Test
Glucose Levels
C-reactive Protein measures level of inflammation
-Immunology
ANA (anti-nuclear antibody) suggests autoimmune disease
DNA
Organ-specific antibodies
-Virology
Herpes simplex serology
Common management strategies for skin diseases
-General measures
Assess need for admission
eg. fluid balance, thermoregulation, nutrition, infection control
-Topical
Anitbacterial agents
Candida corticosteroid creams
Mouthwash
-Systemic
Prednisolone with or without steroid sparing agents
Antibiotics
-Referral
Opthalmology
Dermatology
ENT
Definition of Eczema
- Pruritic (unpleasant sensation of needed to scratch)
- Inflammatory condition associated with dryness and erythema of the skin
- Scratching leads to lichenification and excoriation
Aetiology of Eczema
- Atopic (genetic tendency) so genetic predisposition with strong family history
- Environmental
Pathogenesis of Eczema
- Type 1 Hypersensitivity reaction
- High IgE levels
- Leads to inflammation of the skin
Subtypes of Eczema
-Atopic/Flexural
Often affecting the flexor surfaces
Including elbows, creases of wrists and backs of knees
Also includes exposed skin such as hands, face and feet
-Varicose
Occurs in people with varicose veins (swollen and enlarged veins)
Affects the lower legs in the elderly in particular
-Suborrheic
Affects greasy parts of the face
Behind the ears, genital area and the scalp
-Discoid
Skin becomes itchy, reddened, swollen and cracked
Sometimes looks like psoriasis because more defined
-Lichen simplex
Response to the skin being repeatedly scratched or rubbed over a long period of time
Clinical features of atopic eczema
- Symmetrical
- Very itchy
- Erythematous patches/paupules/vesicles
- Scaling and dry skin
- Excoriations/fissures that appear after lichenification
- Weeping/crusting present
Eczema can be secondary to the following infections
S.aures (yellow crust and weeping)
Herpes simplex (monomorphic lesions)
Managenent of eczema patients
-Avoid soaps, shower gels and contact with irritants
-Advise the use of: Emollients eg. soap substitutes Topical steroids Oral antibiotics Antihistamines (helps patient sleep and stops scratching at night) Wet wraps Acyclovir if suspecting Herpes
Dental relevance of dermatitis
- Pt may be taking corticosteroids
- Eczema may affect the lips
- Dental proffesionals at high risk of developing allergic contact dermatitis
- Psychological affects on patients eg anxiety and depression
Non-atopic dermatitis examples
- Irritant contact dermatitis
- Allergic contact dermatitis
Irritant contact dermatitis definition and cause
-Non-atopic dermatitis
-Domestic irritants such as detergents, cosmetics or soaps
or
-Occupational irritants such as those encountered by those in ‘wet work’ such as dentists, nurses and engineers
Management of ICD
- Remove irritant
- Emollient
- If pt does not respond to removal of the irritant, then make sure there is no allergic contact dermatitis
Allergic contact dermatitis definition and cause
- Form of contact, non-atopic dermatitis
- Contact defined as directly to the skin, inhalation, or ingestion
- Dental materials increasingly common (topical LA and corticosteroids)
- Less common than ICD
- Type IV Hypersensitivity
Management of ACD
- Non-irritant gloves and PPE
- Barrier cream to offer protection
- Topical steroid is the main treatment
- Systemic immunosuppressant may be needed for resistant cases
Difference between ICD and ACD
- ICD rash is often confined to the area where the trigger touched the skin
- ACD more likely to be widespread
Psoriasis vulgaris aetiology
- Chronic plaque psoriasis
- Genetic and environmental factors related
Psoriasis clinical features
- Multiple, well defined erythematous plaques with silvery scale
- Salmon pink
- Often symmetrical
- Scalp and hairline frequently affected
- Knees and elbows
- Nail pitting and subungual hyperkeratosis sometimes present
Main types of psoriasis and definitions
-Guttate psoriasis Raindrop sized lesions Often follows a streptococcal throat infection Lesions <1cm Numerous but non-itchy
-Generalised pustular psoriasis Rare Medical emergency Potentially lethal De novo or in patients with long standing disease Acutely inflamed and sore skin
Treatment of psoriasis
- Emollients/bath oils
- Vitamin D analogues eg. calcipotriol
- Tar preparations but stains clothes and smells bad
- Topical steroids
- Dithranol
- UV and PUVA (photochemotherapy)- UV light good for psoriasis because it is immunosuppressent and calms down the lymphocytes
- Systemic- acitretin, methotrexate, cyclosporin, biologics
Lichen planus Definition and clinical feature
- Pruritic autoimmune disorder of unknown aetiology
- Very itchy and symmetrical
- Flat topped violaceous (of violet colour) papules on skin
- Tends to be on flexor surfaces and lower back
- Can manifest orally
- May result in scarring
Clinical variants of lichen planus
-Hypertrophic
Big, thick plaques
-Annular
Rings
-Plantar
Hands and feet
-Oral
Several subtypes
- Genital
- Scalp- lichen planopilaris
Treatment of lichen planus
-Topical
Emollients
Topical steroids
(Check candida count daily)
-Systemic
Prednisolone
Azathioprine/mycophenolate
Methotrexate
Dental relevance of lichen planus
- Oral lesions often present and are painful
- Consider other mucosal involvement, for example oesophagus and eyes
- Patient may be on corticosteroids and therefore at risk of infection
Differential diagnosis of pruritus
-Xerosis
(dry skin)
-Dietary
Iron deficiency anaemia
-Endocrine
Thyroid disorders, diabetes
-Inflammatory
Eczema, urticaria
-Autoimmune
Lichen planus, dermatitis herpetiformis
-Infective
chicken pox
-Infestation
Scabies
-Parasitic
Cutaneous larva migrans
-Neoplastic
Cutaenous T cell lymphoma
Myeloproliferative
Lymphoma
Viral infections examples: varicella
- Chicken pox
- Shingles- unilateral, dermatomal
- Herpes simplex
- Molluscum contagiosum (pox virus)
- Warts (human papilloma virus)
Bacterial infections: staphylococcus aures/streptococcal infections
Impetigo
Cellulitis
