Dermatology Flashcards
Briefly describe normal skin anatomy
Describe the embryological process of skin development
Epidermis is derived from the ectoderm while the dermis is from the underlying mesenchyme
In the 5th week, the skin of the embryo is covered by simple cuboidal epithelium
In the 7th week there is a single squamous layer (periderm) and a basal layer
In the 4th month an intermediate layer containing several cell layers is interposed between the basal cells and the periderm
In the early foetal period, the epidermis is invaded by melanoblasts (cells of neural crest origin)
Describe the role of the immune system in the skin
Langerhans Cells (dendritic cells) reside in the basal layers of the skin
Acquire antigens in the periphery, transport them to regional lymph nodes to activate naive T-Cells and initiate an adaptive immune response
Activated T-Cells then initiate cytokine release cascade
Describe the effects of UV light on the skin
Direct effects include photoaging, DNA damage and carcinogenesis
p53 tumour suppressor genes are mutated by DNA damage (implicated in development of melanoma and non-melanoma skin cancers)
Chronic exposure can lead to loss of skin elasticity, fragility, abnormal pigmentation, haemorrhage of blood vessels, wrinkling and premature ageing
Describe the aetiology of Acne Vulgaris
- Sebaceous gland hyperplasia and excess sebum production, especially during puberty where androgens drive gland enlargement
- Abnormal follicular differentiation (keratinocytes are retained and accumulate)
- Propionibacterium Acnes colonisation, stimulate the production of pro-inflammatory mediators and lipases
- Inflammation and immune response leads to development of papules, pustules, nodules and cysts
Describe the management options for Acne Vulgaris
- Reduce Plugging:
- Topical Retinoid
- Topical Benzoyl Peroxide
- Reduce Bacteria
- Topical Antibiotics (Erythromycin, Clindamycin)
- Oral Antibiotics (Tetracycline, Erythromycin)
- Reduce Sebum Production
- Hormones - Anti-Androgens (Dianette/OCP)
Describe the role of Isotretinoin in the management of Acne Vulgaris
An oral retinoid (concentrated Vitamin A) for severe Acne Vulgaris
Reduces sebum production, plugging and bacterial colonisation
Standard course of 16 weeks at 1mg/kg
Causes remission in around 80% of teenagers
Trivial Side Effects - Dry Lips, Nose Bleeds, Dry Skin, Myalgia
Serious Side Effects - Deranged Liver Function, Raised Lipids, Mood Disturbance, Teratogenicity
(Must have regular pregnancy tests to prevent pregnancy while on therapy)
Describe how psoriasis may present in the skin
Extensive erythematous, circumscribed, scaly papules and plaques
Describe the immune mechanisms associated with psoriasis
Hyperproliferative disorder where cells migrate from the basal layer to the stratum corneum in just a few days
T-Cell mediated autoimmune response
Abnormal infiltration of T-Cells causes release of inflammatory cytokines including interferon, TNF and interleukins
Causes increased keratinocyte proliferation
Describe treatment options for psoriasis
- Topical Creams and Ointments
- Moisturisers help to reduce flaking and dryness
- Steroids reduce immune response
- Phototherapy Light Treatment
- Non-Specific Immunosuppressant Therapy
- Reduces T-Cell Proliferation
- Encourages VitD to reduce skin turnover
- Risk of burning and skin CA
- Acitretin
- Methotrexate and Ciclosporin
- Immunosuppressants
- Biologics
- Etanercept, Infliximab, Adalimumab
- (Anti-TNF)
Describe the different types of psoriasis
- Chronic Plaque
- Pink-red, well-demarcated plaques with a silver scale especially seen on extensor surfaces of the knees
- Guttate
- Raindrop like psoriasis most commonly seen in young adults and children characterised by an explosive eruption of very small circular or oval plaques over the trunk about 2 weeks after a streptococcal sore throat
- Erythrodermic and Pustular
- Can be life-threatening
- Sterile pustules filled with inflammatory cells
- Associated with malaise, pyrexia and circulatory disturbance
Describe the conditions associated with psoriasis, i.e. psoriatic arthritis and metabolic syndrome
Psoriatic Arthritis - Inflammatory disease often affecting the fingers and toes causing swelling
Metabolic Syndrome - Central Obesity, HTN, T2DM, Low HDL Levels and High Serum Triglycerides
Describe the different subtypes of eczema
- Atopic
- Itch inflammatory skin condition
- Associated with asthma, allergic rhinitis, conjunctivitys and hay fever
- High IgE levels
- 10-15% of infants affected, remission in 75% by 15 years
- Contact
- Precipitated by an exogenous agent
- Type IV Hypersensitivity (Delayed T-Cell Response)
- Common allergens include nickel, chromate, cobalt, fragrance
- Seborrhoeic
- Chronic,scaly inflammatory condition often on the scalp or face
- Overgrowth of Pityrosporum Ovale yeast
- Venous
- Associated with underlying venous disease
Describe the management of eczema
- Atopic
- Emollients
- Topical Steroids
- Bandages
- Antihistamines
- Antibiotics/Anti-Virals
- Avoidance of Exacerbating Factors
- Seborrhoeic
- Scalp - Mediated Anti-Yeast Shampoo
- Face - Anti-Microbial, Mild Sterooid and Simple Moisturiser
- Venous
- Emollient
- Mild/Moderate Topical Steroid
- Compression Bandages/Stocking
- Venous Surgical Intervention
Describe the association between eczema and diseases such as asthma, hay fever etc.
Atopic diseases
Associated with immune response and high IgE levels
Describe how eczema may present in the skin
Pruritic, erythematous and dry patches of skin
Often with a remitting/relapsing course
Describe the effect of UV light on the skin
Direct action of UV light on target cells (keratinocytes) for neoplastic transformation via DNA damage
or
Effects of UV light on the host’s immune system (mainly immune suppression)
Describe the clinical features, prognosis and management of Basal Cell Carcinoma
Most common type of skin cancer
Usually very indolent, rarely metastases or kills
Nodular BCC - >0.5cm raised lesion with a shiny pearly lesion, telangiectasia (blood vessels), and is often ulcerated centrally
Superficial BCC - Often involves only the most superficial layers of the epidermis
Pigmented BCC
Morphoeic/Sclerotic BCC
Managed by surgical excision with a 3-4mm margin
Excellent prognosis, 100% for BCC that has not progressed
Describe the clinical features, management and prognosis of Squamous Cell Skin Carcinoma
Papule/nodule, often eroded at the centre and crusty
Usually in a sun-exposed area
Often a hard, scaly, dome-like structure
Can itch or bleed
Surgical Excision and/or Radiotherapy
<4 risk of metastasis
Describe the clinical features, management and prognosis of malignant melanoma
Malignant tumours of melanocytes resulting in DNA damage, most commonly on the skin but also in the bowels or eyes
Features:
Asymmetry
Borders (irregular)
Colour (variable, multi-pigmented)
Diameter (greater than 6mm)
Evolving over time
For nodular melanoma; Elevated, Firm and Growing
Managed by surgical excision;
If Breslow <1mm - 1cm Margin
If Breslow >1mm - 2cm Margin
Adjuvant chemotherapy if metastatic spread
97% 5Yr SR for Breslow <1mm
71% 5Yr SR for Breslow >4mm
Describe some tumour syndromes with cutaneous presentations
- Gorlin’s Syndrome
- Multiple BCCs, Jaw Cysts, Risk of Breast CA
- Brook Spiegler Syndrome
- Multiple BCCs, Trichoepitheliomas
- Gardner Syndrome
- Soft Tissue Tumours, Polyps, Bowel CA
- Cowden’s Syndrome
- Multiple Hamartomas, Breast CA
Describe the emergency medical and surgical management of patients with severe skin and soft tissue infection
i.e. Necrotising Fasciitis
An immediately life-threatening soft tissue infection with deep tissue involvement
Presents with severe pain and systemic upset, visible necrotic tissue and fascial oedema and gas in soft tissues on imaging
Medical management with IV Flucloxacillin, Benzylpenicillin, Gentamicin, Clindamycin, Metronidazole
Emergency surgical intervention with extensive debridement
Describe the pathology and management of cellulitis
Infection involving the dermis, most commonly beginning in the lower limbs
Often tracks through the lymphatic system and may involve local lymph nodes
Usually caused by beta haemolytic streptococci (often group A strep) or Staph. Aureus
Enron 1a - PO Flucloxacillin or Doxycycline
Enron Ib and II - IV Flucloxacillin or Vancomycin
Enron III and IV - Admission with IV Management and/or Surgical
Describe the range of skin and soft tissue infections and their optimal management
- Impetigo
- Golden encrusted skin lesions with inflammation localised to the dermis
- Caused by S. Aureus and is usually mild and self-limiting
- Can treat with topical fusidic acid or systemic antibiotics
- Tinea
- Superficial fungal infection of the skin or nails, very common particularly on the feet
- Most common causes include Microsporum, Eidermophyton and Trichophyton
- If skin alone, treat with topical terbinafine and if severe or hair/nail involvement then systemic itraconazole or terbinafine
- Soft Tissue Abscess
- Infection within the dermis or fat layers with development of walled off infection and pooled pus
- Best treatment is surgical drainage
Give examples of skin changes seen in endocrine disease
- Thyroid
- Dry Skin (Hypo)
- Thyroid Dermopathy (Pretibial Myxedema, Grave’s Disease)
- Thyroid Acropachy
- Diabetes
- Necrobiosis Lipoidica
- Waxy, yellow
- Often affects the shins and may ulcerate and scar
- Scleredema
- Leg Ulcers
- Granuloma Annulare
- Necrobiosis Lipoidica
- Cushing’s
- Acne, Striae, Erythema, Gynaecomastia
- Addison’s
- Hyperpigmentation, Acanthosis Nigracans
Describe the features of erythema nodosum and state some of the diseases it may be associated with
Tender, red nodules under the skin
Inflammation of the fat underlying the skin
Commonly on the shins
Associated with EBV, Strep Infection, TB, IBD, Sarcoidosis, Pancreatic CA, Non-Hodgkin Lymphoma
Give examples of skin changes seen in nutritional deficiencies
- Vit B6 - Dermatitis
- Vit B12 - Angular Chelitis
- Vit B3 - Pellagra
- Zinc - Acrodermatitis Enteropathica
- Pustules, bullae or scaling
- Vit C - Scurvy
- Punctuate Purpura
- Corkscrew Spiral Curly Hair
- Dry Skin and Hair
- Inflamed Gums
- Patchy Hyperpigmentation
Describe the features of pyoderma gangrenosum and state the disease it is associated with
A rare, severe skin disease in which progressive ulceration develops spontaneously or after skin trauma
Causes deep ulcers, usually on the legs
Associated with IBD, RA and Myeloma
Describe the skin changes seen in internal malignancy
- Necrolytic Migratory Erythema
- Erythematous, scaly plaques on acral, intertriginous and periorificial areas
- Associated with an islet cell tumour
- Erythema Gyratum Repens
- Reddened concentric bands in a whirled woodgrain pattern
- Severe pruritic and peripheral eosinophilia
- Strongly associated with lung CA
- Acanthosis Nigricans
- Smooth, velvet-like, hyperkeratotic plaques in intertriginous areas
Describe Steven Johnson Syndrome and Toxic Epidermal Necrolysis
A severe, mainly drug-induced, blistering disorder
Dermatological emergency
Disease spectrum from SJS –> TEN
(SJS if <10% skin involvement)
Stop offending drug
For TEN: Inpatient derm management, analgesia, fluid balance, infection prophylaxis, special mattress, non-adherent dressing
(TEN may have an up to 50% mortaility)
Describe Erythema Multiforme
A self limiting allergic reaction
Associated with HSV, EBV and occasionally drugs
Characterised by target lesions on the skin
Never progresses to TEN
Describe the acute blistering disorders
- Bullous Pemphigoid
- Tense and blood filled blisters
- Typically on flexure surfaces
- Pemphigus
- Superficial and flaccid blisters
- Typically on the trunk, scalp, mouth
- Treatment of Above
- Immunosuppression (azathioprine, oral steroids)
- Infection control
- Burst any blisters
- Dermatitis Herpetiformis
- Associated with coeliac
- Common on elbows, knees, upper back
- Treated with gluten free diet, topical steroid and oral dapsone
Describe urticaria
Non-scarring, itchy wheals with each lesion lasting <24 hours
Most common skin disorder presenting to A&E
Acute <6 weeks, Chronic >6 weeks
May be immune-mediated (type IgE immune response) or non-immune-mediated (direct mast cell degranulation)
Causes include viral infection, NSAIDs, parasitic infection, opiate
Treated with antihistamines, steroids, immunosuppression or omiluzimab
