Miscellaneous Flashcards
How can psychological stress trigger a skin condition
Activate the hypothalamus and hypophysis resulting in release of neuromediators
Can stimulate release of norepinephrine and cortisol from the adrenal glands
OR
Leukocytes into the blood stream via receptors
Give examples of neuromediators
Corticotropin-releasing hormone, melanocyte stimulating hormone
Role of dryness of skin in defence against infection
Desiccates microorganisms
Role of sebum in defence against infection
Inhibits bacterial growth
What is staph
Gram positive cocci in clusters
Skin and soft tissue treatment options for MRSA
Doxycycline, co-trimoxazole, clindamycin
Clinical relevance of staph. Saprophyticus
Causes UTIs in women of child bearing age
Name 3 bacteria that may be commensals
Staph. Epi
Corynebacterium
Propionibacterium
Give an example of a fungal infection
Candidiasis
Clinical presentation of candidiasis
Infection of the skin folds - under the breasts, groin, abdominal skin folds
Diagnosis of candidiasis
Swab for culture
Management of candidiasis
Clotrimazole cream, oral fluconazole
Who usually gets ringworm
Men
How do we get a ringworm infection
Most commonly from infected humans
Animals
Soil
Causal organisms of ringworm
Trichophyton rubrum, T.mentagrophytes and microsportum canis
Pathophysiology of ringworm
Fungus enters
Hyphae spread to stratum corneum
Increased epidermal turnover causes scaling
Inflammatory response in the dermis
What type of tissue can ringworm infect
ONLY keratinised tissue
How does ring worm infection get its appearance
Lesion grows outwards and heals in the centre leaving a ring appearance
Local management of ringworm
Clotrimazole cream, topical nail paint
Management of scalp ringworm
Terbinafine or itraconozole orally
Who gets scalp ringworm
Children
What causes scabies
Sarcoptes scabiei
Incubation period of scabies
Around 6 weeks
Clinical presentation of scabies
Intensely itchy rash
Burrows
Where does scabies tend to affect
Finger webs, wrists, genital area
Management of scabies
Malathion lotion applied overnight and washed off the next day
Management of lice
Malathion
What are the 3 main components of a dermatology clinical examination
Distribution
Configuration
Morphology
Discrete configuration of lesions
Lesions are well demarcated, can be clearly seen individually
Coalescing configuration of lesions
Individual lesions present but starting to merge together to form larger abnormal areas
Confluent configuration of lesions
No normal skin visible
Annular configuration of lesions
Lesions in a ring-shaped pattern
What is pitting of the nails
Small depressions of the nail plate
What is oncholysis
Separation of the nail plate from bed
What is hypertrichosis
General excess growth of hair
Name some local causes of hypertrichosis
Naevi, faun tail, chronic scarring, inflammation
State general causes of hypertrichosis
Malnutrition, anorexia, porphyria, occult malignancy, drugs
Name some drugs that can cause hypertrichosis
Minoxidil
Phenytoin
Cyclosporin
What is hirsutism
Excess growth in a male pattern
What is erythema
Vascular dilatation
What is purpura
Extravasation of blood
How to differentiate between erythema and purpura
Erythema blanches on pressure
What is petechia
1-2 mm area of flat purpura
What is a macule
Localised flat colour change <1 cm
What is a patch
Localised flat colour change >1 cm
What is a papule
Localised elevated area <0.5cm
What is a nodule
Localised elevated area >0.5 cm
Describe a maculopapular rash
Has both flat and elevated components
What is a plaque
Raised edge and flatter surface >1 cm
What is a pustule
Pus filled raised lesion
What is a vesicle
Fluid filled raised lesion <0.5cm
What is a bulla
Fluid filled raised lesion >0.5 cm
What is a wheal
Compressible dermal swelling
What is a cyst
Nodule containing semi-solid material
What is scale
Accumulated fragments of keratin layer
What is crust
Dried exudate
What is lichenification
Thickening with increased skin markings
What is a scar
Area where normal tissue is replaced by fibrous tissue
What is a fissure
A linear split in the epidermis
What is an erosion
A superficial break in the epidermis
What is an ulcer
A deeper break into the epidermis
What are predisposing factors
Past factors which contribute to the development of a problem
What are precipitating factors
Current factors or stressors that triggered the current problem at this time
What are perpetuating factors
Issues that contribute to the problem continuing
What are heuristics
Mental shortcuts that allow people to solve problems and make judgements quickly and efficiently based on past experiences
What is fundamental attribution error
The tendency to be judgemental and blame people rather than examine the circumstances that might have been responsible for
What is hindsight bias
Knowing the outcome may influence the perception of past events and prevent a realistic appraisal of what actually occurred
What are the 3 main types of hair
Lanugo
Vellus
Terminal
What is lanugo hair
Fine long hairs covering the foetus
Shed around 1 month before birth
What is vellus hair
Fine, short hair covering much of the body surface
Replaces lanugo hairs
What is terminal hair
Long, coarse hairs
What influences terminal hair growth
Androgen levels
Where do we find terminal hair
Scalp and pubic area
What does Hutchinsons sign look like
Spreading pigmentation
What might hutchinsons sign indicate
Malignant melanoma
What causes beaus lines
Transient arrest in nail growth which occurs during acute stress or illness
Name some non-scarring alopecia
Alopecia areata
Traction alopecia
Tines capitis
Name some scarring causes alopecia
CDLE
lichen planus
Frontal fibrosinf alopecia
What are virulence factors
Factors responsible for pathology and variation in virulence within and between groups of pathogens
Name 5 virulence factors
Adhesin
Invasin
Impedin
Agressin
Modulin
How does adhesin work
Enables binding of the organism to the host tissue
How does invasin work
Enables the organism to invade the host cell or tissue
How does impedin work
Enables the organism to avoid the host defence mechanisms
How does agressin work
Causes damage to the host directly
How does modulin work
Induces damage to the host indirectly
What is the commonest cause of toxic shock
TSST-1
What causes scalded skin syndrome
Exfoliating toxins A and B from staph aureus
Clinical sign of scalded skin syndrome
Positive nikolsky sign
Where is scalded skin syndrome usually seen
Neonatal face, axilla and groin
What is toxic shock syndrome linked to
Tampon use
Diagnostic criteria for toxic shock
Fever >39
Diffuse macular erythroderma and desquamation
Hypotension
>3 organs involved
How does protein A act as a virulence factor
Binds to the Fc portion of antibodies, rendering them inaccessible to opsonins, impairing phagocytosis
How does coagulase act as a virulence factor
Protects against phagocytosis
What is coagulase
Protein enzyme tightly bound to the surface of staph aureus which can coat its surface with fibrin upon contact with blood
How does a capsule act as a virulence factor
Protects bacteria against phagocytosis
What is Panton-valentine leukocidin
Specific secreted proteins that form one functional complex that attacks white blood cells
Describe strep pyogenes
Gram positive cocci in chains, coagulase negative
Where in the body is strep pyogenes usually found
Pharynx
What most commonly causes necrotising fasciitis type 2
Strep pyogenes
What is the risk of an affected child if a parent has an autosomal dominant disorder
50%
What is haploinsufficiency
Only one copy of working gene
What happens in dominant negative mutations
Expression of abnormal protein interferes with the normal protein
What happens in a gain of function mutation
Mutant protein gains a new function affecting cell processes
What is the risk of an affected child if the parent is a carrier of an autosomal recessive disease
1/4
What are the 5 layers of the scalp
Skin
Connective tissue
Aponeurosis
Loose connective tissue
Periosteum
What nerve supplies motor function to the muscles of mastication
The Trigeminal nerve
How many divisions does the Trigeminal nerve have
3
Name the divisions of the Trigeminal nerve
- Opthalamic
- Maxillary
- Mandibular
How do we test for the Trigeminal nerve
Gently brush the skin of each dermatome while the patient has their eyes closed
Get them to tell you when they feel it
Compare on both sides
Roles of the facial nerve (4)
Controls the facial expression muscles
Controls inner ear that moderates volume of sound
Helps make tears
Relays information about taste to the brain
Clinical testing of the motor function of the facial nerve
Frown, close eyes tightly, smile, puff out cheeks
Name the methods of local anaesthesia (4)
Topical
Local infiltration
Nerve block
Field block
What should be used with lignocaine as an anaesthetic
Adrenaline
Why is adrenaline used alongside anaesthesia
Prolongs it and reduces bleeding
When is electrosurgery used
Treatment of minor skin lesions
What happens in a snip excision
Grasp lesion with skin hook and cut across the base of the lesion
When is a snip excision used
Minor skin lesions
What is curettage
Scraping of abnormal tissue
What is a shave excision
Flat blade of a scalpel drawn through a raised lesion to remove it
What does an elliptical excision look like (to me)
An eye
Why do we not worry about UVC rays
They are blocked by the ozone layer
Which UV is our biggest concern
UVA
Compare the wavelengths of UVA and UVB
UVB has a shorter wavelength
Benefits of UVR exposure
Vitamin D synthesis
Heat
Vision
Circadian rhythms
Bactericidal and virucidal
Therapeutic and diagnostic uses
How can UVR cause immunosuppression (3)
Depletion of langerhans cells in the skin and reduced ability to present antigens
Generation of UV induced regulatory T cells with immune suppressive activity
Secretion of anti-inflammatory cytokines
How does UVB cause DNA damage
Absorbed by DNA in the nucleus of a keratinocyte
Induces covalent linkages between pyrimadines in the same DNA strand producing CPDs and 6-4 PPs
What are CPDs
Cyclobutane pyrimadine dimers
How does UVA cause mutations
Indirect oxidative damage
Signature mutation caused by UVB
CC - TT mutation
Signature mutation caused by UVA
C - A point mutation
What is an oncogene
Overactive form of a gene that positively regulates cell division
What is a tumour suppressor
A gene that negatively regulates cell division to prevent the formation of a tumour
Give some examples of erythematous exanthems that start on the face
Measles, rubella, erythema infectiosum
What causes rubella
Togavirus
Clinical presentation of erythema infectiosum
Slapped cheek on the face
Virus associated with erythema infectiosum
HSV 6
Give some examples of erythematous exanthems that tend to start on the trunk
Roseola
Scarlet fever
Unilateral laterothoracic exanthem
At what point are you no longer infectious with chicken pox
Until all lesions are crusted over
Management of chickenpox
Acyclovir in immunosuppressed patients
What causes measles
Paramyxovirus called MeV
How does measles spread
From person to person via respiratory droplets
How does measles spread through the body
Enters through the respiratory tract, spreads to regional lymph nodes and then to other organs
Clinical presentation of measles
Fever >39
Generalised maculopapular rash
One or more of: conjunctivitis, cough, coryza
Koplik spots
A sign of measles before the onset of a rash
Investigations for measles
PCR
serology: IgM, IgG
Viral isolation
Prevention of measles
Live vaccine
Who cannot receive a live vaccine
People who are immunosuppressed
Complication of measles
Increased risk of bacterial superinfection
Pathophysiology of HSV
Virus enters epidermis and penetrates endings of sensory and autonomic nerves
Establishes a latent infection in local ganglia
Reduction in immune function leads to reactivation
Clinical presentation of HSV
Localised vesicular rash
Neuropathic pain
Fever, malaise
Investigation for HSV
PCR
Management of HSV
Acyclovir
What is the MOA of acyclovir
Inhibits the activity of viral DNA polymerase and prevents the virus from multiplying and spreading in the body
Role of thyroid hormone in the skin
Promotes fibroblasts activity
Regulates epidermal differentiation
Essential for hair formation and sebum production
Effects on skin perfusion
Name some places in the skin you may find thyroid hormone receptors
Keratinocytes, fibroblasts, arrector pili muscle cells, sebaceous gland cells
What is first line for phototherapy
UVB
When is PUVA first choice
Mycosis fungoides, pityriasis rubra pilaris, pustular psoriasis or erythrodermic psoriasis
Common side effect of UVB therapy
Erythema
What should be done before starting any phototherapy
Minimal phototoxic dose test
When might UVA1 treatment be used
Atopic eczema
Granuloma annulare