Dermatology Flashcards
Define psoriasis
A chronic autoimmune inflammatory skin condition characterised by hyperproliferation of keratinocytes causing scaly, erythematous, circumscribed papules with a silver scale
Summarise the aetiology of psoriasis and the risk factors of psoriasis
Aetiology is unknown
Genetic component - FHx
Precipitating factors: Stress Smoking Infection Alcohol Skin injury Medication
Guttate psoriasis - streptococcal sore throat
Palmar-plantar psoriasis - smoking, middle-aged women, autoimmune thyroid disease
Generalised pustular psoriasis - hypoparathyroidism
Summarise the epidemiology of psoriasis
Mean age of onset 28 years old
Equal in men and women
Affects 1-2% of the population
What are the presenting symptoms of psoriasis?
AUSPITZ SIGN - Pinpoint bleeding with removing scales
Skin lesions may develop at sites of trauma/scars (Koebner phenomenon)
Plaque psoriasis (most common type): Itchy Well circumscribed purple/red/salmon flattened areas of elevation White/silver scales Found on scalp and extensors Dry flaky skin Painful
Guttate psoriasis:
Itchy, red small raindrop plaques on back
Following strep throat infection
Pustular planto-palmar:
Small fluid filled pustules on hands and feet
Flexural:
Red, shiny itchy rash found in skin folds (axilla, groin, perianal, under breast
Erythrodermic:
Systemic body redness and inflammation
Painful and itchy
What are the signs on physical examination of psoriasis?
Nail signs:
Oncholysis (nail falling off nail bed)
Pitting
Subungal hyperkeratosis - scaling under nail
Signs of psoriatic arthritis: Asymmetrical oligoarthritis Symmetrical polyarthritis Distal interphalangeal joint predominance Arthritis mutilans Psoriatic spondylitis
Plaque psoriasis - symmetrical, well-demarcated erythematous plaques with silvery scales over extensor surfaces (knee, elbows, scalp, sacrum)
Flexural psoriasis - red, shiny, less scaly plaques in axilla, groins, perianal and genital skin
Guttate psoriasis - small drop-like lesions over trunk and limbs
Palmoplantar psoriasis - erythematous plaques with pustules on palms and soles
What are the appropriate investigations for psoriasis?
Usually a clinical diagnosis which requires no investigations
Skin biopsy can confirm diagnosis
Guttate psoriasis: anti-streptolysin-O titre, throat swab
Flexural psoriasis: skin swabs to exclude candidiasis
Nail clipping analysis for onychomycosis (fungal infection)
Joint involvement analysed by checking for rheumatoid factor and radiographs
Define herpes simplex virus
Herpes simplex virus is a enveloped, double stranded DNA virus
Infection with HSV-1 or HSV-2 can cause oral, genital, and ocular ulcers. The primary episode occurs during initial infection with HSV, in which the host lacks an antibody response.
HSV-1: mainly oral herpes herpes
HSV-2: mainly genital herpes
HHV-3: varicella-zoster virus - chickenpox and shingles
Summarise the aetiology of herpes simplex virus
HSV1 causes herpes labialis (cold sores)
HSV2 causes genital herpes
HSV are large, enveloped, double stranded DNA viruses
HSV-1 and HSV-2 are acquired at mucosal surfaces or at breaks in the skin. The virus replicates in the epidermis, then infects sensory or autonomic nerve endings and travels by retrograde axonal transport to sensory ganglia.
In the latent phase HSV lives in trigeminal ganglia (face sensory neuron cell bodies) and sacral ganglia (genital sensory neuron cell bodies)
Periodic reactivation of the virus produces lytic replication when the virus travels by anterograde transport down axons to the mucosal or cutaneous surface
Reactivation triggers:
Stress
Skin damage
Viral infection
Summarise the epidemiology of herpes simplex virus
Infection most commonly acquired during childhood
Seropositivty increases with age
Prevalence of HSV1 and HSV2 higher among women
Very common
What are the presenting symptoms of herpes simplex virus
Herpes labialis - cold sores Painful sores in the genital area Itchiness Dysuria Vaginal discharge Fever Headache Flu like prodrome for HSV2 Gingivostomatitis - dry crusting sore of mouth Sore throat
Keratoconjuncitivitis: Red, painful inflammed eye Sensitivity to light Tearing Blurring of vision Herpetic whitlow - rash on fingertip Tingling sensation
Immunocompromised patients may have more severe, prolonged ulceration of the genital or oral mucosa than immunocompetent patients.
What are the signs on physical examination of herpes simplex virus?
Fever Pharyngitis Lymphadenopathy Bilateral tender inguinal lymphadenopathy Multiple tender 1-2 cm erythematous ulcerations Oedematous cervix Pustules Clear discharge
What are the appropriate investigations for herpes simplex virus?
Mainly clinical diagnosis based on appearance of blisters
Viral culture - detect HSV
HSV PCR - positive
Type-specific serological IgG assay: positive antibody to HSV1 or HSV2
Define lipoma
A slow growing, benign tumour composed of adipose tissue, usually found in the subcutaneous tissues particularly of the trunk and proximal limbs. They form well-circumscribed, lobulated lesions composed of adipocytes which are demarcated from surrounding fat by a thin, fibrous capsule
Summarise the aetiology of lipoma
Mostly idiopathic
Hereditary:
Familial multiple lipomatosis
Gardner’s syndrome
Madelung’s disease - benign symmetric lipomatosis on head, neck, shoulders - MEN WITH HEAVY ALCOHOL CONSUMPTION
Dercum’s disease - painful lipomas on trunk, shoulders, arms and legs - MIDDLE AGED WOMEN
MEN 1
Summarise the epidemiology of lipoma
1% of population
Occur at any age
Most common between 40-60 years old
What are the signs and symptoms of lipoma?
SOFT, MOBILE, SUPERFICIAL MASS Usually painless Cutaneous mass <5cm diameter Well circumscribed lesion Separated from surrounding fat by thin, fibrous capsule Skin coloured Smooth normal surface Soft/doughy feeling Fluctuant NOT transilluminate
GI obstruction or bleeding if lipoma found in GI tract
What are the appropriate investigations for lipoma?
Mainly a clinical diagnosis
Can use CT/MRI/USS if doubt about diagnosis - show discrete, encapsulated, homogeneous mass with similar density to normal fat
Biopsy - histology consistent with lipoma
Define erythema nodosum
A common type IV hypersensitivity reaction leading to inflammation of subcutaneous fat, resulting in raised tender purple nodules often over the shins.
Summarise the aetiology of erythema nodosum
25% of cases have no identifiable cause
Infection: Strep pyogenes (MOST COMMON CAUSE) Tuberculosis HIV Chlamydia Leprosy EBV Histoplasmosis
Systemic inflammation:
IBD
Sarcoidosis
Behcets disease
Drugs:
Sulphonamides
Amiodorone
Oral contraceptives
Pregnancy
Malignancies:
Haematological malignancies
Carcinoid tumours
Pancreatic cancer
Summarise the epidemiology of erythema nodosum
Peaks between 20-30 years old
More common in females
Associated with pregnancy
What are the presenting symptoms of erythema nodosum?
Bilateral, tender, red/purple erythematous nodules often on the shins
Lesions appear for 1-2 weeks and leave bruise-like discolouration as they resolve
Lesions do not ulcerate and resolve without atrophy or scarring
May be associated with fever, arthralgia
Fatigue
Anorexia
Weight loss
Symptoms of underlying cause:
GI symptoms (change in bowel habit, blood in stool, abdominal pain) - IBD, Behcets
Cough and SOB - TB
What are the signs on physical examination of erythema nodosum?
Bilateral, poorly defined, red/purple dome-shaped nodules most commonly on the shins
Occasionally appear on the thighs and forearms
Nodules are tender to palpation
Low-grade pyrexia
Joints may be tender and painful on movement
Signs of underlying CAUSE
What are the appropriate investigations for erythema nodosum?
Biopsy if uncertain of diagnosis
Investigations to identify the cause
Bloods:
FBC, ESR, CRP - suggestive of infection (often a leukocytosis)
Serum ACE - raised in sarcoidosis
Anti-streptolysin-O titres - check for streptococcal infection)
m ACE (raised in sarcoidosis)
Throat swab and cultures - check for streptococcous
Mantoux/Head skin testing - for TB
CXR - check for bilateral hilar lymphadenopathy or other evidence of TB, sarcoidosis or fungal infections
If suspect IBD, faecal calprotectin, colonoscopy
Define erythema multiforme
An acute hypersensitivity reaction often due to infections, mainly HSV and mycoplasma, leading to skin and mucosal inflammation. It is characterised by target lesions.
Explain the difference between erythema multiforme minor and major
Erythema multiforme minor NO mucosal involvement
Erythema multiforme major has 2+ mucosal sites involved
Summarise the aetiology of erythema multiforme
Precipitating factor only found 50% of the time
Usually due to a preceding infection Most commonly HERPES SIMPLEX VIRUS and MYCOPLASMA PNEUMONIAE Can also be due to: HIV EBV CMV Hep B Herpes zoster Sulphonamides Penicillins Anticonvulsants
Other precipitating factors:
Inflammatory - e.g. rheumatoid arthritis, SLE, sarcoidosis, ulcerative colitis
Malignancy - e.g. lymphomas, leukaemia, myeloma
Radiotherapy
Summarise the epidemiology of erythema multiforme
Can occur in any age group More common in males Peak incidence in 20s and 30s 20% of cases occur in children Children often have more severe form Recurrent in 30% of patients
What are the presenting symptoms of erythema multiforme?
Prodrome - fever, aches
Rapid onset over 24-48 hours Symmetrical Target lesions - central necrosis surrounded by erythematous rings Tender, itchy, burning rash Lesions start on hands and spread
Lesions may fade and leave pigmentation
Erythema multiforme major:
Painful, itchy, crusting, bleeding ulcerations on mouth
What are the signs on physical examination of erythema multiforme?
Classic target (bull’s eye) lesions with a rim of erythema surrounding a paler area
Vesicles/bullae
Urticarial plaques
Lesions are often symmetrical and distributed over the arms and legs including the palms, soles and extensor surfaces
What are the appropriate investigations for erythema multiforme?
Mainly a clinical diagnosis
FBC - elevated WCC
ESR/CRP - elevated
U&Es - may show elevated BUN, creatinine if dehydrated due to decreased fluid intake (painful ulcers involving mouth make this harder)
HSV serology
Cold-haemagglutination serology - positive if mycoplasma
Mycoplasma pneumoniae titre
Imaging – exclude sarcoidosis and atypical pneumonia
Skin biopsy – histology and direct immunofluorescence if in doubt about diagnosis
Define molluscum contagiosum
Cutaneous disorder caused by pox virus resulting in pink, pearly, smooth papules with central umbilication, affecting children and immunocompromised adults mainly by direct skin to skin contact
Summarise the aetiology of molluscum contagiosum
Caused by molluscum contagiosum virus, a type of pox virus
MCV 1 and 1v are seen in children as the result of child-to-child contact or fomites
MCV 2 is a sexually transmitted virus noted in the groin in adults or generalised in immunocompromised adults
MCV 3 is a rare subtype in any age group
Summarise the epidemiology of molluscum contagiosum
Most commonly children - affects 5-12% of children
90% of patients are under 15 years old
More common in tropical climates
What are the presenting symptoms of molluscum contagiosum?
Incubation period: 2-8 weeks
Usually ASYMPTOMATIC papules
Pearly, flesh coloured papules which form dome
There may be tenderness, pruritus and eczema around the lesion in 1/3rd of patients
Lesions last for around 8 months
What are the signs on physical examination of molluscum contagiosum?
Firm, smooth, umbilicated papules
Usually 2-5 mm in diameter
In children: tends to occur on the trunk and the extremities
In adults: tends to occur on the lower abdomen, genital area and inner thighs (suggesting sexual contact)
Surrounding erythema, inflammation and swelling
What are the appropriate investigations for molluscum contagiosum?
Mainly clinical diagnosis
Curretage biopsy - shows Henderson-Patterson bodies
Dermatoscopy
Define cellulitis and erysipelas
A spreading acute bacterial skin infection usually caused by streptococcus pyogenes or staphylococcus aureus.
Cellulitis is a deep infection of the dermis and subcutaneous tissue.
Erysipelas is a superficial infection of the epidermis and superficial lymphatics.
Summarise the aetiology and risk factors of cellulitis and erysipelas
Most common beta haemolytic group A streptococcus pyogenes or staphylococcus aureus
Risk factors:
Open wound - trauma, bite, wound, ulcer, cannula
Immunosuppression - diabetes, HIV, alcohol use
Summarise the epidemiology of cellulitis and erysipelas
Common condition
More common in extremes of age or immunocompromised
What are the presenting symptoms of cellulitis and erysipelas?
Lesion: Red Painful Oedematous/swollen Warm Acute onset
Erysipelas - raised, well demarcated, prodrome of fever, malaise
What are the signs on physical examination of cellulitis and erysipelas?
Erythematous, oedematous, tender rash on extremities or face
Cellulitis - poorly demarcated
Erysipelas - well demarcated, raised
What are the appropriate investigations for cellulitis and erysipelas?
FBC - increased WBC
ESR/CRP - elevated
Blood culture
Wound swab and culture - MC&S
What is the appropriate management of cellulitis and erysipelas?
Conservative: Analgesia Bed rest Elevation Draw around it to monitor spread or shrinkage Fluids Sterile dressings
Medical:
Antibiotics - oral flucloxacillin (IV if severe)
Vancomycin if MRSA
What are the possible complications of cellulitis and erysipelas?
Sepsis
Necrotising fasciitis
Abscess
Local necrosis
Summarise the prognosis of cellulitis and erysipelas
The prognosis of cellulitis is excellent.
Most episodes of cellulitis resolve with therapy, and major sequelae are absent
May leave residual damage to draining lymphatics and perhaps increase the likelihood of recurrence in the future
Define pressure sores
Localised injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure or of pressure in combination with shear.
Summarise the aetiology and risk factors of pressure sores
Constant pressure limits blood flow to the skin leading to tissue damage
They occur as a result of pressure, friction and shear
Risk factors: Elderly Immobile Impaired sensation Diabetes
Summarise the epidemiology of pressure sores
Very common in hospitals
Occurs more commonly in elderly
What are the presenting symptoms and signs on physical examination of pressure sores?
Occurs mostly over bony prominences or body parts eg sacrum and heel
subjected to sustained localised pressure
Shallow open wound or tissue loss on areas of pressure
Tenderness and warmth around area
They may become infected leading to fevers, erythema and foul smell
What are the appropriate investigations for pressure sores?
NO investigations necessary - Clinical diagnosis
Waterlow Score is used to predict risk of pressure sores in patients
Define varicella-zoster
Infection with varicella-zoster virus (a type of herpesvirus HSV3) which causes chickenpox in the acute infection, remains dormant in the dorsal root ganglion and can reactivate in times of stress and shingles
Summarise the aetiology of varicella-zoster
Caused by infection with HSV3 varicella-zoster virus
Spread by respiratory droplets and direct lesion contact
Primary infection causes chickenpox
VZV can remain dormant in the dorsal root or trigeminal ganglia for many years
When stressed, immunocompromised, increased age can reactivate to cause shingles
Chickenpox is contagious from 48 hours before until all vesicles have crusted
Summarise the aetiology of varicella-zoster
Chickenpox - more common in children, peak 4-10 years old
Varicella peak >50 years old
What are the presenting symptoms and signs on physical examination of varicella zoster?
Chickenpox:
Fever, headache, weakness
Flat, red, itchy spots on trunk, scalp and face which become elevated and then develop into fluid-filled vesicles
Crust over in 1-2 days
Shingles:
Pain, itching tingling in dermatomal lesion
Unilateral painful vesicular rash in dermatomal distribution
What are the appropriate investigations for varicella zoster?
Mainly clinical diagnosis Swab of lesion: PCR - VZV DNA Viral culture - positive VZV Blood test for varicella antibodies
Histology of vesicle fluid - multinucleated giant cells
What is the management of varicella zoster?
Chickenpox:
Supportive - analgesia, antihistamine, calamine lotion for anti-pruritic properties
Adults with chickenpox - oral acyclovir, valaciclovir or famciclovir if immunocompetent, IV if immunocompromised
Shingles:
Oral acyclovir
What are the possible complications of varicella zoster?
Chickenpox: Skin infection Scarring Pneumonia Hepatitis Encephalopathy Meningitis
Shingles:
Postherpetic neuralgia
Herpes zoster ophthalmicus - can lead to blindness
Superinfection of skin lesions
Ramsay-Hunt syndrome - ear pain, hearing loss, tinnitus, facial weakness
Summarise the prognosis of varicella zoster
Chickenpox is a self-limiting illness
Define candidiasis
Candidal/yeast infection of the skin, most commonly caused by candida albicans Infections include: Oral candidiasis (oral thrush) Angular cheilitis Vulvovaginal candidiasis (genital infection in women) Balanitis (penile infection) Intertrigo (skin fold infections) Napkin dermatitis (nappy or diaper rash) Chronic paronychia (nail fold infection) Onychomycosis (nail plate infection) Chronic mucocutaneous candidiasis
Summarise the aetiology of candidiasis
Most common causative agent is candida albicans
Often opportunistic infection in those who are immunocompromised when invasive candidiasis
Risk factors:
Diabetes mellitus
Antibiotics - causes destruction of other bacteria allowing candida overgrowth
Inhaled corticosteroids
Immunosuppresion - HIV, long-term corticosteroids, chemotherapy, radiotherapy
Extremes of age
High oestrogen - contraceptive pill, pregnancy
Warm climate
Underlying skin condition
Summarise the epidemiology of candidiasis
40-70% of health children and adults
What are the presenting symptoms and signs on physical examination of candidiasis?
White, fluffy, cottage cheese-looking plaques in mouth, buccal cavity etc
Can be scraped off which may cause pain and shows underlying red, inflamed mucosa which may bleed
Vulvovaginitis - dysuria, thick white discharge, itching
Oseophageal candidiasis - dysphagia, odynophagia, white plagues in oesophagus
Erythema, Maceration, Satellite pustules, soreness and pruritus
What are the appropriate investigations for candidiasis?
Tissue swab - microscopy and culture
Blood culture
Candida PCR
Candida antigen testing
Define epidermoid and pillar cysts
An epithelial-lined, keratinous, debris-filled cyst often caused by a blocked hair follicle
Summarise the aetiology of epidermoid and pillar cysts
Occlusion of the pilosebaceous gland
Can be caused by traumatic insertion of epidermal elements into the dermis
Embryonic remnants
Epidermoid cyst - lined by epidermis-like cells
Pillar cyst - lined by cells which look like those found in hair roots
Summarise the epidemiology of epidermoid and pillar cysts
Very common at any age
What are the presenting symptoms of epidermoid and pillar cysts?
Non-tender, slow-growing, round, firm skin swelling
There are often multiple
Common on hair-bearing regions of the body - face, scalp, trunk or scrotum
May become red, hot and tender if there is superimposed infection or inflammation
What are the signs on physical examination of epidermoid and pillar cysts?
Firm, round, tethered lump under the skin
Overlying skin punctum
May discharge granular creamy material that smells bad
What are the appropriate investigations of epidermoid and pillar cysts?
None
Skin biopsy or FNA if needed to rule out other diagnosis
Define urticaria
A red, erythematous, raised, blanching, oedematous rash, likely due to histamine from mast-cell degranulation
Acute - lasts <6 weeks - often due to hypersensitivity allergic reaction
Chronic - >6 weeks
Summarise the aetiology of urticaria
Mast cell degranulation and activation leading to release of histamine
Causes capillary leakage, which causes swelling of the skin and vasodilation - erythematous appearance
ACUTE urticaria:
Idiopathic
Allergies (foods, insect bites, stings, drugs)
Viral or parasitic infections
Skin contact with chemicals
Hereditary causes (in some cases of angioedema)
Physical stimuli - scraping skin, very hot or cold temperatures
CHRONIC urticaria:
Chronic spontaneous urticaria - medication, stress, infections
Autoimmune
Idiopathic
Summarise the epidemiology of urticaria
Lifetime prevalence for acute urticaria - 20%
Acute urticaria more common in children and adolescents
Chronic urticaria mainly affects adults and more often women
Acute urticaria more common than chronic
What are the presenting symptoms and the signs on physical examination of urticaria?
Red, erythematous, oedematous, blanching, raised lesions on the skin
Well-demarcated
Wheals - itchy with central white papule
40% associated with angioedema - swelling of soft-tissue of eyes, face, tongue, lips
Urticaria: swelling involving the superficial dermis, raising the epidermis (itchy wheels)
Angioedema: deeper swelling involving the dermis and subcutaneous tissues (tongue, lips)
Anaphylaxis: bronchospasm, facial and laryngeal oedema, hypotension
Acute - symptoms develop quickly but normally resolve within 48 hours
Chronic - rash persists for > 6 weeks
What are the appropriate investigations of urticaria?
Clinical diagnosis in acute
May later use patch testing to determine cause
Chronic requires further investigations to determine cause:
FBC, ESR/CRP, IgE receptor antibody positive in chronic autoimmune urticaria
