Dermatology Diseases Flashcards
What are the two types of eczema?
Atopic eczema and contact dermatitis
What is the clinical presentation of eczema?
- Itchy red rash
- Crusting, scaling and oozing
- Atopic eczema= Normally in skin folds such as elbow and knee
- Contact dermatitis= Sharply demarcated skin inflammation
What is the pathophysiology of atopic eczema?
A defect om the epithelial barrier (Thinning of stratum corneum due to damaged fillagrin) which allows irritants in to come into contact with T helper 2 cells (CD4) lymphocytes. This leads to inflammation.
What is the aetiology of atopic eczema?
Genetics and exacerbating elements
What is the epidemiology of atopic eczema?
Most common form
What is the pathophysiology of contact dermatitis?
Chemical irritants lead to a type IV hypersensitivity reaction
What is the aetiology of contact dermatitis?
Exposure to irritants
What is the epidemiology of contact dermatitis?
Women more than men
What is the treatment path of eczema?
- Avoid irritants
- Emollient therapy (E.G. E45)
- Topical corticosteroids
- Topical calcineurin inhibitor
How much emollient should be applied for eczema?
Apply 3-4 times a day
- 250-500g/week for child
- 500-750g/week for adult
What topical corticosteroids can be used in eczema?
Mild= Hydrocortisone
Moderate= Clobetasol butyrate
Potent= Flucinonide
Very potent= Clobetasol propinate
How is eczema diagnosed?
High serum IgE in 80%, and must have itchy skin condition in last 6 months. Plus 3 or more of-
- History of involvement of skin creases
- History of asthma/ Hay fever
- Generally dry skin
- Onset in childhood
What are possible complications of eczema?
Scratching will lead to broken skin, which then causes opportunistic infection.
What is the most common malignant skin cancer?
Basal cell carcinoma
Briefly describe the pathophysiology of basal cell carcinoma
Slow growing, locally malignant epidermal tumour. Thought to arise from hair follicles. Infiltrates local tissues through slow irregular growth of fingerlike outgrowths
What are the risk factors for basal cell carcinoma ?
UV exposure
Skin type 1: skin that burns and doesn’t tan
Aging
How is basal cell carcinoma diagnosed?
Biopsy
What is the clinical presentation of basal cell carcinoma ?
Non-pigmented in 95%
Border of ulcerated lesions is raised with peachy appearance
Majority occur in elderly on head and neck
Slowly enlarging, shiny nodule, which bleeds following minor trauma
Slowly causes local tissue destruction
Slowly invasive= Rarely metastasises
How is basal cell carcinoma treated?
Surgically excised with white borders and histology to ensure clear and adequate tumour margins
Superficial BCCs can be managed with non surgical treatment= Cryotherapy, photodynamic therapy
Radiotherapy in those unable to tolerate surgery
What are some complications of basal cell carcinoma ?
Maetastasis are rare (5%) but very hard to treat. Damage occurs if local spread reaches other structures
What is bowen’s disease?
In situ squamous cell carcinoma confined to the epidermis
What is the epidemiology of squamous cell carcinoma?
2nd most common skin cancer, just below basal cell carcinoma= 20% of non-melanoma skin cancer
What are the risk factors for squamous cell carcinoma?
Age
UV exposure
Chronic inflammation e.g. wound scars
What is the clinical presentation for squamous cell carcinoma?
Tends to present in later life
Most common on sun-exposed sites
Lesions are often keratoic, ill defined nodules that may ulcerate
They can grow rapidly
Ulcerations on lower lip or ear are more aggressive
Examinations of the regional lymph nodes is essential to look for metastasis
How is squamous cell carcinoma diagnosed?
Biopsy
Examine regional lymph nodes to look for metastasis
How is squamous cell carcinoma treated?
Surgical excision with minimal margin of 5mm
Radiotherapy is also used
What are some complications of squamous cell carcinoma?
Metastasis are rare (5%) but hard to treat
What is cellulitis?
A poorly demarcated bacterial infection of dermis and sub-cutaneous tissue
What is the epidemiology of cellulitis?
Preferentially involves lower extremities
What is the aetiology of cellulitis?
- Group A beta-haemolytic strep e.g. S. Pyogenes (Most common)
- Staph. Aureus
- MRSA
What are the risk factors for cellulitis?
- Lymphoedema
- Leg Oedema
- Obesity
- Leg Ulcer
- Immunosuppression
- Traumatic Wounds
Briefly explain the pathophysiology of cellulitis?
Typically affects lower leg or arm, and spreads proximally. Other sites that may be affected include the abdomen, perianal and periorbital areas. Can also affect one side of face
What are the clinical features of cellulitis?
- Local inflammation with proximal spreading
- Erythema in affected area with poorly demarcated margins, warmth, swelling and tenderness
- Occasionally will blister if oedema is severe
- Systemically unwell with pyrexia
How is cellulitis treated?
- Rest, analgesia and elevate limb
- Antibiotics e.g. oral flucloxacillin or oral phenoxymethylpenicillin
- Oral erythromycin if penicillin allergic
- If widespread infection, antibiotics IV for 3-5 days, then 2 weeks oral therapy
- If recurrent, prophylaxis low dose antibiotics
How is cellulitis diagnosed?
- Clinical
- Skin swabs are usually negative unless taken from broken skin
- Serological testing to confirm a strep infection
What are some possible complications from cellulitis?
- Abscess
- Gangrene
What is the epidemiology of malignant melanoma?
Commonly affects younger patients
Responsible for the most deaths caused by cancer in men
Incidence is rising due to excessive sun exposure
Common in affluent people and those who excessively drink
What are the risk factors for malignant melanoma?
UV exposure Red hair High density freckles Skin type 1 Atypical moles Immunosuppression Multiple melanocytic naevi Family history
What are the four types of malignant melanoma?
Superficial spreading
Nodular
Lentigo maligna= On face
Acral= On palms/ soles
What is the clinical presentation of malignant melanoma?
Commonest site in men is back/chest Commonest site in women is lower legs ABCDE - Asymmetrical shape - Border irregularity - Colour irregularity - Diametre > 6mm - Elevation/ evolution Also crusting and bleeding, inflammation, sensory changes, itching
What is the differential diagnosis of malignant melanoma?
Benign pigmented naevus, seborrhoeic wart, pyogenic granuloma
How is malignant melanoma treated?
- Surgical excision is curative in early cases
- Limited sensitivity to radiotherapy
- Treatment of metastatic disease
What is the prognosis of malignant melanoma?
- Thin lesions have best prognosis
- Generally there is a female advantage in prognosis
- Poor prognosis if present on trunk vs limbs
What is the most common variant of acne?
Acne. Vulgaris
What is the epidemiology of acne?
- Usually starts in adolescence
- Often resolves in mid 20s
- Affects face, back and chest
- Prevalence ranges from 70-87% in teenagers
Briefly explain the pathophysiology of acne
Narrowing of hair follicles due to hypercornification blocking the entrance to hair follicles. Results in increased sebum production. Some sebum becomes trapped in the narrow hair follicle. Sebum stagnates in pit of follicle where there’s no oxygen. This creates anaerobic conditions that allow p. acnes to multiply. P. acnes breaks down triglycerides in sebum into FFAs resulting in inflammation, irritation and attraction of neutrophils= Pus formation.
What are the clinical features of acne?
- Whiteheads= Closed comedones
- Blackheads= Open comedones
- Skin coloured papules
- Inflammatory lesions usually occuring when the closed wall of comedones ruptures
- Papules, pustules, or nodules
How is acne diagnosed?
- Clinical diagnosis
- Skin swabs for culture
- Hormone test in females
How is mild acne treated?
- Benzyl peroxide gel/cream
- Topical antibiotics
- Topical retinoids
How is severe acne treated?
- Oral tetracyclines e.g oral doxycycline, then oral minocycline
- Hormone treatment= anti androgen treatment
What is the epidemiology of psoriasis?
- 2% of population
- Peak prevalence in early adulthood, 2nd peak at 50-60yrs
Briefly explain the pathophysiology of psoriasis?
Psoriasis is a T lymphocyte driven disorder to an unidentified antigen T cell activation results in upregulation of Th1 types T cell cytokines. Upregulation of these cytokines results in increased uncontrolled hyperproliferation of the keratinocytes in the epidermis with an increase in epidermal turnover rate.
List the types of psoriasis
- Chronic plaque psoriasis
- Flexural psoriasis
- Guttate (Raindrop like) psoriasis
- Palmoplantar psoriasis
- Erythrodermic and pustular
How is general psoriasis treated?
- Topical= Reassurance and emollient. Possibly corticosteroids e.g. hydrocortisone
- Vit D analogues= Clacipotriol cream
- Phototherapy= Ultraviolet A radiation with photosensitising agent
- Systemic therapy= Oral retinoic acid derivatives
- Calcineurin inhibitors= tacrolimus (immunosuppressants)
- Ultraviolet B
- Coal tar
- Anti-mitotic e.g. dithranol cream
What is the epidemiology of neuropathic ulcers?
Most commonly found in diabetes and neurological disease due to peripheral neuropathy
What are the clinical features of neuropathic ulcers?
Ulcers tend to have a variable size and may be surrounded by callus.
How are neuropathic ulcers treated?
- Keep ulcer clean and remove pressure or trauma
- Correctly fitting shoes and specialist podiatrist help for diabetics
What is the epidemiology of arterial ulcers?
Commonly a history of claudication, hypertension, angina or smoking
What are the risk factors for arterial ulcers?
- Arterial disease e.g. atherosclerosis
- Smoking
- Hypercholesterolaemia
- Diabetes mellitus
How are arterial ulcers diagnosed?
- Doppler ultrasound will confirm arterial disease
- Ankle brachial pressure index suggest arterial insufficiency
What are the clinical features of arterial ulcers?
- Typically present as punch-out ulcers higher up the leg or on the feet
- Intense pain
- Leg is cold and pale
- Absent peripheral pulses
- Ulcer is small, sharply defined and necrotic
How are arterial ulcers treated?
- Keep ulcer clean and covered
- Analgesia e.g. ibuprofen
- Vascular reconstruction if appropriate
What is the epidemiology of venous ulcers?
- Venous ulcers are the most common type of leg ulcer
- Common in later life
- Affect 1% of population over 70 yrs
- Most commonly found on lower leg
What causes venous ulcers?
- Sustained venous hypertension = Previous DVT, incompetent leg vein valves, atherosclerosis, vasculitis
What are the clinical features of venous ulcers?
- Sloping and gradual edges
- Ulcer is large, shallow, irregular and exudative
- Usually minimal pain
- Oedema
- Venous eczema
- Brown pigmentation
- Varicose veins
How are venous ulcers diagnosed?
- Ankle brachial pressure index is normal
- Doppler ultrasound to exclude significant arterial disease
How are venous ulcers treated?
- High compression 4 layered bandage
- Leg elevation
- Antibiotics if infected
- Analgesia
- Support stockings for life
A child presents with a weeping rash around the chin and mouth. What is it likely to be, and what pathogen is associated?
Impetigo
Strep Pyogenes
How would you treat impetigo?
Oral flucloxacillin
What is necrotising fasciitis?
A deep seated infection of the subcut tissue that results in a fulminant and spreading destruction of fascia and fat, but intially spares the skin
What are the 2 types of necrotising fasciitis?
- Type one; Anaerobic and aerobic bacteria following abdominal surgery or in diabetics
- Type 2; Group A beta-haemolytic strep (S. Pyogenes)
What are the clinical features of necrotising fasciitis?
- Severe pain that is out of proportion to skin findings
- Infection track rapidly along the tissue planes, causing spreading erythema , pain and crepitus
- Fever, toxicity
- Multi organ failure
What are the risk factors for necrotising fasciitis?
- Abdominal surgery
- Immunosuppression
How is necrotising fasciitis diagnosed?
Soft tissue gas seen on X ray
Raised CRP and WCC
How is necrotising fasciitis treated?
- Aggressive and prompt antibiotics for confirmed group A streptococci= Benzylpenicillin and clindamycin
- If unknown aetiology= IV metronidazole and broad spectrum antibiotics
