Dermatology Flashcards by Shrey Paun

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

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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?

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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

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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

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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

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Macule definition and example

Patch of skin that is well circumscribed but not palpable
<1cm in diameter
eg. Freckle

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Patch definition and example

Patch of skin that is well circumscribed but not palpable
> 1cm in diameter
eg. Lentigo maligna

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Papule definition and example

Well circumscribed, palpable elevation
<1cm in diameter
eg. Lichen planus
Often very itchy and associated with keratosis and ulcers orally

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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

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Nodule definition and example

Palpable elevation
> 1cm in diameter
eg. nodular malignant melanoma

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Vesicle definition and example

Blister
<0.5cm in diameter
eg. pompholyx eczema on the thenar eminence (palm)

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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

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Scale definition and example

Peeling of the stratum corneum

- Eg. severe eczema

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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??

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Ulcer definition and example

Full thickness loss of epidermis

- Ulcerated nodular basal cell carcinoma

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Scar definition and example

Permanent change in skin surface/texture

- eg. Lichen planus in the scalp which is just a bald patch

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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

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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