Dermatology CBL Flashcards
What epithelium is the epidermis?
Stratified squamous keratinising epithelium
5 epidermal layers
Basale Spinosum Granulosum Lucidum Corneum
Langerhan Cells
Dendritic cells, residing in epidermis. Ingest, rpocess and present antigens to T lympocytes
Melanocytes
Originate in neural crest and migrate to skin during early development. Live in dermis or epidermis and make pigment (melanin). Also important for skin and hair pigmentation.
Diff dx of chronic, red scaly skin?
Psoraisis Exzema Seborrhoeic dermaitits Tinea (fungal) Pityriasis rosea
Clinical features of psoriasis
Well demarcated plaques on extensor surfaces
Silvery scale, hyperkeratosis
Salmon-pink inflammatory base
Flexural involvement around ears
Painful hacks and fissures within plaques on feet
Risk factors for psoriasis
Genetic - HLA subtypes.
Environmental - drugs e.g. lithium
Infection
Stress
Pathogenesis of psoriasis
Hyperproliferatioon of epidermal keratinocytes leading to reduction in transit time from basal layer to stratum corneum.
Activation of t-lymphocytes.
Thickening of epidermis, epidermal neutrophils and dilated dermal capillaries
Production of cytokines e.g. TNFa and Interleukins
Rheumatological signs linked with psoriasis
Pain and tenderness on active and passive movement of fingers and toes
Synovitis/red/swelling
Limited range of movements
Stiff sore back
Psoriatic arthropathy
Seronegative arthritis typically affecting the sacro-illiac and distal interphalangeal joints
Psoriasis is more common in px with which disease?
Chrons disease
Tests for psoriatic arthritis
FBC, Inflamm markers (CRP), RF (Negative), Alkaline phosphatase
Treatment for psoriasis
Topical - tar, corticosteroids, retinoids, Vit D3 analogs, dovobet
Systemic - retinoids, immunosuppression (methotrexate)
Final option - biological (infliximab, adalumimab)
Itchy skin, improves on holiday?
Atopic eczema most likely, possible element of allergic contact dermatitis
Factors involved in development of atopic eczema?
Defective barrier function i.e. genetic fillagrin skin protein dysfunction, irritant soaps, overworking, poor handcare
Investigations for atopic eczema
Skin swab (2ndary bacterial infection) Consider fungal skin scrape to exclude tinea
Contact dermatitis patch testing
IgE count
Tx of atopic eczema
Emollient moisturisers (creams and oinments)
Potent topical steroid
Finger tip unit applications
If doesnt improve -
UV phototherapy
Oral alitretinoin
Systempic immunosuppresives (methotrexate)
Alopecia areata clinical symptoms/features
Well circumscribed areas of hair loss Non scarring Follicular architecture intact Hair pull test positive Vellous white hair growth Occassional nail changes
Aetiologies involved in development of alopecia areata
Exact mechanism unknown - possible autoimmune?
Therapies for alopecia areata
Topical steroid Injected steroid Irritant contact dermatitis treatments e.g. DCP UVB phototherapy Minoxidil for widespread hair loss
Different patterns of non-scarring alopecia areata?
Single patch, localised Multiple patches Widespread Alopecia totalis Alopecia universalis Parietal pattern
What conditions may cause hair loss including those that scar?
Androgenic male pattern hair loss
Scalp cellulitis
Syphilis
Untreated ringworm
Brown marks on skin differential dx
Melanocytuic naevi (moles) Seborrhoeic keratoses (warts) Freckles Melanoma Hyperpigmentation Pigmented basal cell carcinoma
Melanoma important dx features
Irregularity in shape or colour
Change in size
Bleeding or ulceration, inflammation, irritation
Lesions >5mm
Findings on biopsy of melanoma
> 5mm
Active melanocytic lesion with junctional and invasive intradermal component
Cells are large, contain mitotic features
Pale cells are neoplastic melanocytes spreading in the epidermis –> dermis
Stain for melan A
Breslow thickness
Risk factors for melanoma
UV irradiation (natural and artificial)
Countries with populations of white skinned individuals exposed to strong sunshine
Genetic
Numerous atypical naevi
Genetic mutation in melanoma
Tumour suppressor gene CDKN 2A
Preventative measures for melanoma’s
Avoid UV exposure - sunblock
Avoid sunburn
Stop using sunbeds
Follow up px with atypical naevi or strong fhx of melanoma
Most important prognostic feature for melanoma?
Tumour thickness - breslow thickness
Staging for melanomas
Stage 1 - Tumours <1mm thick
Tumours 1-2mm thick without ulceration
Stage 2 - Tumours 1-2mm thick with ulceration
Stage 3 - regional lymph node involvement
Stage 4 - Distant metastases
Tx of melanoma
Excision with narrow margins then wide local excision
Sentinel node studies offered to px with thicker melanomas
Distinguishing arterial with venous ulcer?
Venous tends to be less painful, more superficial and diffuse
Social/lifestyle factors involved in the development of venous ulcer?
Multiple pregnanices
Varicose veins
Standing in a shop
Important initial inv in venous leg ulcer
Ankle brachial pressure index should be roughly equal
0.8 ratio may suggest occulsion
Initial tx for venous leg ulcer
Compression - 3 layer bandaging
Compression stockings
Moisturiser emollient
Topical steroid
If the ulcer didn’t heal - what other investigations should be done?
MRI angiography SKin biopsy incase of ISD Bacterial swabs Exclude drug ulceration Patch testing for bandages, dressings and steroids
Causes of leg ulceration
Arterial Diabetic Neuropathic Pressure sores Trauma Infection
Teenage px presents with spots on face. What is the differencial dx?
Acne vulgaris
Rosacea
Folliculitis
Pustular drug reaction
Features needed for a diagnosis of acne vulgaris
Papules
Pustules
Comedones
May also be evidence of scarring, hyperpigmentation, nodules
Chest, back and upper arms may also be involved
Aetiology of acne vulgaris
Seborrhoea, sebum retention and inflammation
May be related to excess sensitivity of sebaceous end organs to androgens
Ovarian or adrenal hyperandrogenism
Sebum retention is hyperkeratinisation of the sebaceous duct
Therapies for acne vulgaris
Topical antiseptics - benzyl peroxide Topical Antibiotics - clindamycin Oral antibiotics - limecycline, doxycyline Duac - clindamycin/benzyl peroxide OC - Dianette Oral retinoids - isotretinoin
Implications of using oral isotretinoin in a teenage girl
Common side effects - Swelling of lips Fragile and weaker skin Nosebleeds Photosensitivity Elevated liver enzymes Alopecia Vision problems
Serious side effects - Major birth defects Depression Erectile dysfunction Hepatotoxicity
Irregular menstruation, excess hair and severe acne?
Consider PCOS and congenital adrenal hyperplasia
Do hormone profiling - testosterone, progesterone, prolactin
Social and psychological implications of acne
Depression
Social withdrawal
Self esteem and body image issues
Dysmorphophobic acne
Some px consider their minor acne to be severe.
A genetic compound deficiency within the skin has been implicated in eczema, what is it?
Filaggrin deficiency
