Dermatology Flashcards
What is atopic dermatitis?
Inflammatory skin condition characterised by dry pruritic skin which a chronic relapsing course
What is the aetiology of atopic dermatitis?
- Multifactorial aetiology, combination of genetic susceptibility and environmental factors contributing to disease development
- Defects in skin’s barrier function and immune dysregulation following allergen exposure are thought to be key components in the development of this disease
What is the epidemiology of atopic dermatitis?
- Usually presents in childhood
- Remission is notes by 15 years of age mostly but relapse may occur later
What are the presenting symptoms of atopic dermatitis?
- Presence of risk factors: under 5yrs, FHx, allergic rhinitis, asthma, antihelminth tx in utero
- Pruritis
- Xerosis (dry skin)
- Sites of skin involvement: Infants- cheeks, forehead, scalp. Children: flexures esp. wrist, ankle
What are the signs of atopic dermatitis on examination?
- Erythema
- Scaling
- Vesicles
- Papules
- Keratosis pilaris
- Excoriations
- Lichenification
- Hypopigmentation
What are the investigations for atopic dermatitis?
Clinical diagnosis: features of dermatitis Can consider: - Allergy testing - IgE levels: elevated - Skin biopsy
What is basal cell carcinoma?
Commonest form of skin malignancy, also known as ‘rodent ulcer’
What is the aetiology of basal cell carcinoma?
- Prolonged sun exposure or UV radiation
- Associated with abnormalities of the patches/hedgehog intracellular signalling cascade, as seen in Gorlin’s syndrome (naevoid basal cell carcinoma syndrome).
- Other risk factors include photosensitising pinch, tar and arseninc
What is the epidemiology of basal cell carcinoma?
- Common in those with far skin and areas of high sunlight exposure
- Common in elderly, rare before age of 40
- Lifetime risk in Caucasians is 1:3
What are the presenting symptoms of basal cell carcinoma?
A chronic slowly progressive skin lesion usually on the face but also on the scalp, ears or trunk
What are the signs of basal cell carcinoma on examination?
- Nodulo-ulcerative (most common): Small glistening translucent skin over a coloured papule that slowly enlarges (early) or a central ulcer (‘rodent ulcer’) with raised pearly edges. Fine telangiectatic vessels often run over the tumour surface. Cystic change may be seen in larger more protuberant lesions.
- Morphoeic: Expanding, yellow/white waxy plaque with an ill-defined edge (more aggressive)
- Superficial: Most often on trunk, multiple pink/brown scaly plaques with a fine ‘whipchord’ edge expanding slowly; can grow to more than 10cm in diameter
- Pigmented: Specks of brown or black pigment may be present in any type of basal cell carcinoma
What are the investigations for basal cell carcinoma?
Biopsy is rarely necessary (Dx is based mainly on clinical suspicion)
What is contact dermatitis?
An allergic or irritant skin reactions caused by an external agent
What is the aetiology of contact dermatitis?
The top 5 allergens found to cause contact dermatitis in children were nickel sulfate, ammonium persulfate, gold sodium thiosulfate, thimerosal, and toluene-2,5-diamine
What is the epidemiology of contact dermatitis?
- Rare in first few months of life, but prevalence increases with age
- Gender differences may be attributed to social and environmental factors; females are more likely to have nickel sensitivity because of increased wearing of jewellery, and males are more likely to have chromate sensitivity from occupational exposure.
What are the presenting symptoms of contact dermatitis?
- Risk factors: occupation with frequent exposure to water of caustic material, atopic dermatitis
- Previous similar episodes
- Acute onset
- Affecting hands and face
- Affecting sun-exposed skin
- Sparing of non-exposed areas of skin
- Pruritis
- Burning
What are the signs of contact dermatitis on examination?
- Erythema
- Vesicles and bullae
- Lichenoid lesions
- Corrosion or ulceration
- Scaling
What are the investigations for contact dermatitis?
- Patch testing: positive result show inflammation graded on a 1+ to 3+ scale within 2-7 days of application
- Repeated open application test pr provocative use test: Inflammation or dermatitis at application site
What is eczema?
A pruritic papulovesicular skin reaction to endogenous or exogenous agents
What is the aetiology of Eczema?
Numerous varieties caused by a diversity of triggers
- Exogenous: Irritant, contact, phototoxic
- Endogenous: Atopic, seborrhoeic, pompholyx, varicose, lichen simplez
- Irritant: Prolonged skin contact with a cell-damaging irritant
- Contact: Type IV delayed hypersensitivity to allergen
- Atopic
- Seborrhoeic: Pityrosporum yeast
- Varicose: Increased venous pressure in lower limbs
What is the epidemiology of eczema?
- Prevalence: 4%
- Atopic: Onset is commonly in first year of life
What are the presenting symptoms of eczema?
- Itching (can be severe)
- Heat, tenderness, redness weeping, crusting
- Enquire into occupational exposures or irritants used at home (e.g. bleach)
- Enquire into family/personal history of atopy (e.g. asthma, hay fever, rhinitis)
What are the signs of acute eczema on examination?
- Poorly demarcated erythematous oedematous dry scaling patches
- Papules, vesicles with exudation and crusting, excoriation marks
What are the signs of chronic eczema on examination?
- Thickened epidemis
- Skin lichenification
- Fissures
- Changes in pigmentation
What are the signs of different types of eczema on examination?
- Contact & irritant: Eczema reaction occurs where irritant/allergent comes into contact with skin
- Atopic: Particularly affects face and flexures
- Seborrhoeic: Yellow greasy scales on erythematous plaques, particular in the nasolabial folds, eyebrows, scalp and presternal area
- Pompholyx: Acute and often recurrent vesicobullous eruption on palms and soles
- Varicose: Eczema of lower legs, associated with marked varicose veins
- Nummular: Coin shaped on legs and trunk
- Asteototic: Dry, ‘crazy’ pairing’ pattern
What are the investigations for contact eczema?
Skin patch testing: Disc containing postulated allergen in diluted and applied to back for 48h
- Positive if allergen induces a red raised lesion
What are the investigations for atopic eczema?
Swab for infected lesions (bacteria, fungi, viruses)
What is erythema multiforme?
An acute hypersensitivity reaction of the skin and mucous membranes
- Stevens-Johnson syndrome is a severe form with bullous lesions and necrotic ulcers
What is the aetiology of erythema multiforme?
- Drugs: Sulfonamides, penicillin, phenytoin, barbiturates
- Infection: Viral (HSV, EBV, coxsackie, adenovirus, ORF), Bacterial (M. pneumoniae, Chlamydiae), Fungal (Histoplasmosis)
- Inflammatory: Rheumatoid arthritis, SLE, sarcoidosis, UC, systemic vasculitis
- Malignancy: Lymphomas, leukaemia, myeloma
- Radiotherapy
What is the epidemiology of erythema multiforme?
- Non specific prodromal symptoms of upper respiratory tract infection
- Sudden appearance of itching/burning/painful skin lesions, may may fade, leaving behind pigmentation
What are the signs of erythema multiforme on examination?
- Classing target (bulls eye) lesions with a rim of erythema surrounding a paler area, vesicles/bullae, urticarial plaques
- Lesions are often symmetrical, distributed over the arms and legs including the palms, soles and the extensor surfaces
What are the investigations for erythema multiforme?
Usually unnecessary as is a clinical diagnoses. But can identify precipitating factor
- Blood: Raised WCC, eosinophils, ESR, CRP, throat swab, serology, albumin
- Imaging: CXR: Exclude sarcoidosis and atypical pneumonias
- Skin biopsy
What is erythema nodosum?
Panniculitis (inflammation of the subcutaneous fat tissue) presenting as red or violent subcutaneous nodules
What is the aetiology of erythema nodosum?
Delayed hypersensitivity reaction to antigens associated with various infectious agents, drugs and other diseases
- Infection: Bacterial (Strep, TB, Yersinia, Chlamidya), viral (EBV), fungal (histoplasmosis), protozoal (toxoplasmosis)
- Systemic disease: Sarcoidosis, IBD, Behcet’s disease
- Malignancy: Leukaemia, Hodgkin’s disease
- Drugs: Sulphonamides, penicillin, Oral contraceptive pill
- Pregnancy
What is the epidemiology of erythema nodosum?
Usually affects young adults
Female: Male: 3:1
What are the presenting symptoms of erythema nodosum?
- Tender red or violet nodules develop bilaterally on the shins and occasionally on the thighs and forearms
- Fatigue, fever, anorexia, weight loss and arthralgia are often also present
- Symptoms of the underlying aetiology
What are the signs of erythema nodosum on examination?
- Crops of red or violet-dome shaped nodules usually present on both shins (occasionally involving thighs or forearms), which are tender to palpation
- Low-grade pyrexia. Joints may be tender and painful on movement
- Signs of the underlying aetiology
What are the investigations for erythema nodosum?
To determine underlying aetiology
- Blood: Anti-streptolysin-O titre at diagnosis and 2-4 weeks later to assess for antecedent strep infection. FBC, U&E, CRP, ESR, LFT
- Throat swab and culture
- Mantoux/Heaf skin testing: for TB
- CXR: Look for hilar adenopathy or other evidence of pulmonary sarcoidosis
What are lipomas?
Slow growing benign tumours of adipose tissue
- Lipomatosis: Multiple contagious lipomas that cause distortion of SC tissues
What is the aetiology of lipomas?
- Unknown
- A rare presentation is multiple tender lipomas (Dercum’s disease)
What is the epidemiology of lipomas?
- All ages
- Mostly 40-60
- Rare in children
- No gender preference
What are the presenting symptoms of lipomas?
- Pt notices lump, usually painless and slowly enlarging, unless subject to trauma when fat necrosis may cause it to swell and become tender
What are the signs of lipomas on examination?
- Can occur anywhere there are adipose tissue reserves, common in the SC tissue of the upper arms
- Nontender, soft, compressible, but do not usually fluctuate or transilluminate except if large
- Do not have fluid thrill and are dull to percussion
- Overlying skin usually normal
- Variable size, usually ovoid or spherical, often lobulated
- Local lymph nodes should not be palpable
What are the investigations for lipomas?
- Usually none necessary
- MRI can be used visualising deeply sited lipomas
What is melanoma?
Malignancy arising from neoplastic transformation of melanocytes, the pigment forming cells of the skin. Leading cause of death from skin disease.
What is the aetiology of melanoma?
- DNA damage in melanocytes caused by UV radiation results in neoplastic transformation
- 50% arise in pre-existing naevi, 50% in previously normal skin.
What are the histological types of melanoma?
1) Superficial spreading: typically arises in pre-existing naevus, expands in radial fashion before vertical growth phase
2) Nodular: Arises de novo, aggressive, no radial growth phase
3) Lentigo maligna: More common in elderly with sun damage, large flat lesions, follow an indolent growth course. Usually on the face
4) Acral lentiginous: Arise on palms, soles and sublungual areas. Most common type in non-white populations
What is the epidemiology of melanoma?
- Steadily increasing incidence
- White races have 20x increased risk to non-white races
What are the presenting symptoms of melanoma?
- Change in size, shape or colour of pigmented skin lesions
- Redness
- Bleeding
- Crusting
- Ulceration
What are the signs of melanoma on examination?
ABCD criteria for examining moles A Asymmetry B Border irregularity/bleeding C Colour variation D Diameter over 6mm E Elevation
What are the investigations for melanoma?
- Excisional biopsy: Dx and determination of Clark’s levels or Breslow thickness
- Lymphoscinigraphy
- Sentinel lymph node biopsy
- Staging: Ultrasound, CT or MRI, CXR
- Blood: LFT (liver is common site of metastases)
What is molluscum contagiosum?
- Condition caused by molluscum contagiosum virus which escapes immune destruction for months to years
What is the aetiology of molluscum contagiosum?
3 types of lesions
- MCV 1 and 1v seen in children as result of child-to-child contact or fomites
- MCV 2 is sexually transmitted and noted in the groin in adults and generalised in immunocompromised people
- MCV 3 is a rare subtype in any age group
What is the epidemiology of molluscum contagiosum?
- No sex or ethnic trend
What are the presenting symptoms of molluscum contagiosum?
- Presence of risk factors: close contact with infected indiv, sexual contact with infected indiv, HIV infection, tropical climate
- Facial or groin distribution of lesions
- Atopic dermatitis
What are the signs of molluscum contagiosum on examination?
- Pearly papule with a central dell
- Surrounding erythema
- Pruritis
What are the investigations for molluscum contagiosum?
- Clinical dx
- Curettage biopsy
- Tzanck stain: purple ovoid keratinocytes
- Haematoxylin and eosin staining: Henderson-Paterson bodies
- HIV test
What are pressure sores?
Skin damage and ulcers caused by pressure on weightbearing areas, typically tissue over bony prominences
What is the aetiology of pressure sores?
Pressure over susceptible tissues results in impaired perfusion, ischaemia, cell death and skin breakdown
What are the risk factors for pressure sores?
- Extrinsic: Pressure, shear, friction, moisture
- Intrinsic: Age, immobility, sensory impairment, incontinence, protein-calorie nutrition
What is the epidemiology of pressure sores?
- Common
- 70% in those over 70
What are the presenting symptoms of pressure sores?
- Area of erythema or ulcer may be noticed by carer, less frequently the pt may complain of pain in the affected area
- Predisposing factors should be ascertained
- Ischaemic injury responsible may have occurred early on in a hosp stay
What are the signs of pressure sores on examination?
Vulnerable areas are over sacrum, coccyx, ischial tuberosities, greater trochanter malleoli and heels, also the occiput and scapulae
What are the investigations for pressure sores?
- Wound swab, FBC, blood cultures if infection suspected
- Plain radiographs, bone or Gallium scans, MRI or needle bone biopsy if underlying osteomyelitis is suspected
What is psoriasis?
Chronic inflammation skin disease which has characteristic lesions and may be complicated by arthritis
What is the aetiology of psoriasis?
- Unknown
- Genetic, environmental factors and drugs (e.g. may be triggered by streptococcal infections, antimalarial agents, B-blockers, lithium)
What are the risk factors for psoriasis?
- Guttae psoriasis: Streptococci sore throat
- Palmoplantar pustulosis: Smoking, middle-aged women, autoimmune thyroid disease, SAPHO
- Generalised pustular: Hypoparathyroidism
What is the epidemiology of psoriasis?
- Affects 1-2% of population
- Peak age of onset- 20 yrs
What are the presenting symptoms of psoriasis?
- Itching or occasionally tender skin
- Pinpoint bleeding with removing scales (Auspitz phenomenon)
- Skin lesions may develop at the site of trauma/scars (Koebner phenomenon)
What are the signs of psoriasis on examination?
- Discoid/nummular psoriasis: Symmetrical well demarcated erythematous plaques with silver scales over extensor surface
- Flexural psoriasis: Less scaly plaques in axilla, groins, perianal and genital skin
- Gluttate: small drop like lesions over trunk, limbs
- Palmoplantar: Erythematous plaques with pustules distributed over limbs and torso
- Nail: Pitting, oncholysis, subungual hyperkeratosis, salmon patch on nail
- Joints: seronegative arthritis
What are the investigations for psoriasis?
Majority don’t need investigations
- Gluttate psoriasis: Anti-streptolysin-O tire, throat swan
- Flexural lesions: Skin swabs (exclude candidiasis)
- Nail: Analyse nail clippings to exclude onchomycosis
- Joint involvement: Rheumatoid factor negative, radiographs, sacrolitis
What are sebaceous cysts?
Epithelium-lined, keratinous, debris-filled cyst arising from a blocked hair follicle
More correctly known as epidermal cyst
What is the aetiology of sebaceous cysts?
- Occlusion of the pilosebaceous gland
- Traumatic insertion of epidermal elements into the dermis and embryonic remnants
What is the epidemiology of sebaceous cysts?
Extremely common any age
What are the presenting symptoms of sebaceous cysts?
- Non-tender slow growing skin swelling, often multiple
- Common on hair-bearing areas of the body, especially face, scalp, trunk or scrotum
- May become red, hot and tender if superimposed inflammation or infection
What are the signs of sebaceous cysts on examination?
- Smooth tethered lump with overlying skin punctum
- May express granular creamy material with an unpleasant smell
What are the investigations for sebaceous cysts?
- None usually required
- Skin biopsy of FNA may rarely be necessary to rule out other differentials
What is squamous cell carcinoma?
Malignancy of the epidermal keratinocytes of the skin
- Marjolin’s ulcer is a squamous cell carcinoma that arises in an area of chronically inflamed/scarred skin
What is the aetiology of squamous cell carcinoma?
- Main aetiological risk factor is UV radiation from sunlight exposure, acitinic keratoses
- Radiation, carcinogens (tar deriratives, cigarette smoke, soot), chronic skin disease, HPV, long term immunosuppression (HIV), DNA repair genetic defects (xeroderma pigmentosum
What is the epidemiology of squamous cell carcinoma?
- Second most common cutaneous malignancy
- Often occurring in middle aged and elderly light skinned individuals
- Male: Female 2-3:1
What are the presenting symptoms of squamous cell carcinoma?
- Skin lesion
- Ulcerated
- Recurrent bleeding or non-healing
What are the signs of squamous cell carcinoma on examination?
- Variable appearance: ulcerated, hyperkeratotic, crusted or scaly, non healing lesion, often on sun-exposed areas
- Palpate for local lymphadenopathy
What are the investigations for squamous cell carcinoma?
- Skin biopsy: Confirms malignancy and distinguishes it from other skin lesions
- FNA or lymph node biopsy: if suspicious of metastases
- Staging: CT and/or MRI, PET scanning
What is urticaria
- Also knows as hives
- Is a skin rash with red, raised, itchy bumps which may also burn or sting
- Patches often move around
What is the aetiology of urticaria?
- Medications: allergic reactions: codeine, ibuprofen, aspirin
- Food: Allergies: Shellfish and nuts in adults. Shellfish, nuts, eggs, wheat and soy
- Infection or environmental agent
- Dermatographic urticaria: marked by appearance of weals or welts on the skin as a result of scratching or firm stroking of the skin
What is the epidemiology of urticaria?
- Acute urticaria more common in people with atopy and mostly in children and young adults
What are the presenting symptoms of urticaria?
- Welts (raised areas surrounded by red base
- Itching
- Swelling that causes pain or burning
- Signs and symptoms flare with triggers such as heat, exercise and stress
- Symptoms recur frequently and unpredictably, sometimes months or years
- Angioedema
What are the signs of urticaria on examination?
- Head: areas of alopecia
- Face: lip or eyelid swelling, oral ulcers and dry eyes
- Neck: Cervical lymphadenopathy, thyromegaly or thyroid nodules
- Pharynx: strep throat with injection and tonsillar enlargements with crypts
- Extremities: angio-oedema and axillary lymphadenopathy
What are the investigations for urticaria?
- Strep throat: throat culture
- Suspected allergic urticaria: skin prick testing
- Suspected aquagenic urticaria: Lukewarm water immersion
