Transcript PHYSICAL FACTORS IN DERMATOLOGY

PHYSICAL FACTORS
IN DERMATOLOGY
HEAT/BURN
excessive heat on skin, divided into 3 types:
1st. Degree: only erythema with
constitutional symptoms if a large area is
affected.
2nd. degree: superficial type causing bullae,
healing with no scarring, or deep healing by
scarring.
3rd. degree: loss of full thickness skin +
underlying structures healing by scarring
HEAT
MILIARIA
Retention of sweat as a result of occlusion of
sweat duct, causing rupture of gland & escape of
sweat, 3 types according to level of obstruction:
1- crystallina: in stratum corneum.
2- rubra: in prickle cell layer.
3- profunda: in upper dermis.
HEAT
ERYTHEMA AB IGNE
Persistent erythema or the coarsely reticulated
residual pigmentation resulting from it, due to
long exposure to excessive heat without burn.
First transient, then permanent
Legs of women
May cause epithelial atypia, rarley Bowen’s disease
or squamous cell carcinoma.
COLD
PERNIOSIS
Localised erythema & swelling caused by exposure
to cold, with even sometimes blistering or
ulceration.
It is cold hypersensitivity.
Mostly hands, feet, ears, & face in children.
Onset may be enhanced by dampness
Bluish red, cool to touch+ burning & itching
Treatment is preventive, spontaneous recovery
COLD
FROST BITE
Freezing of tissue due to exposure to
extremely low temperature, a form of toxic
effect.
Painless, pale & waxy+ various degrees of
tissue damage as in burn depending on the
temperature & duration of exposure.
Treament is by rapid re-warming +
supportive measures
SUN
ACTINIC INJURY
Solar spectrum has many regions according to
wavelength, most important is UVL.
UVA 320-400nm
UVB 290-320 nm
UVC 200-290 nm
UVB has more than 1000 more erythmogenic
effect than UVA, & is more in midday hours.
Either sunburn or photosensitivity
SUN
SUNBURN
Normal reaction of skin to sunlight in excess of
erythema dose.
Erythema starts after 6 hours, peaks in 12-24 hrs.
Followed by tenderness & severe cases blistering.
May be associated by edema of face, limbs, fever,
chills, nausea & hypotension.
Desquamation follows in a week
treatment: analgesics+ soothing agents
SUN
PHOTOSENSITIVITY
Abnormal reaction to normal sun exposure
1- Chemical photosensitivity: by photosensitizres
which are either applied topically as in
phytophotodermatitis, or internally by enteral or
parenteral adminstrtion of drugs as in
phototoxic drug reactions.
2- Metabolic: as in porphyria, & pellagra
SUN
PHOTOSENSITIVITY
3- light exacerbated disorders: genetic or acquired
as SLE, Darier’s, vitiligo, acne, small % of
psoriasis, dermatomyositis, lichen planus
actinicus, & chloasma.
4- Idiopathic photosensitivity: most common is
polymorphic light eruption: onset in first 3
decades, with a ratio of 2-3: 1 ♀:♂
POLYMORPHIC LIGHT
ERUPTION
Different morphologies in different people
Constant morphology in the same patient
Mostly is papular or erythemapapular form but
could be papulovesicular, eczematous,
erythematous & plaque like.
Healing only with dyspigmentation
Mostly on sun exposed skin
Starts in spring, improve in summer
TREATMENT
1- AVOIDANCE
2- TOPICAL STEROIDS
3- ANTIHISTAMINES
4-SYSTEMIC STEROIDS
5- ANTIMALARIALS
6- LIGHT THERAPY
7- IMMUNOSUPPRESSANTS
Mechanical injury
callus & clavus
CALLUS: circumscribed hyperkeratosis induced
by pressure, diffuse with no central core.
CLAVUS: (corn): circumscribed conical
thickenning with base on surface & apex down
pressing on subjacent structures, of 2 types:
Soft corns
Hard corns