1. Cutaneous photosensitivity reactions require absorption of light energy by molecules, leading to damage and clinical disease.
2. Common photosensitivity disorders include polymorphic light eruption (PLE), chronic actinic dermatitis (CAD), and solar urticaria.
3. Clinical features, histopathology, and phototesting help differentiate types of photosensitivity dermatoses.
TEST BANK For Guyton and Hall Textbook of Medical Physiology, 14th Edition by...
Approach to photodermatoses
1.
2.
3. An abnormal response to light, occurring
within minutes, hours, or days of exposure
and lasting up to weeks, months
4. Cutaneous photosensitivity reactions require
absorption of photon energy by appropriately
shaped molecules leading to molecular
deformity. Energy is either dispersed
harmlessly or is directed to chemical reactions
that lead to molecular, cellular, and tissue
damage resulting in clinical disease
7. Chronic &repeated sun exposures over time
result in polymorphic skin changes called as
dermatohiliosis/photoaging
8. Dermatoses which are caused by an
abnormal reaction of skin to sunlight, usually
to its UV component.
9.
10. Forehead
Nose
Chin
Ears
V of the neck
Dorsal of hands forearm feet
Nails
11. Around the orbits
Under the frame of spectacles
Upper lip
Under the nose
Below chin
12. Behind ears
Under hair on forehead and back of neck
Under wrist watch
Distal phalanges
Web spaces
13.
14.
15. SPT Basic skin color Response to sun exposure
I Pale Do not tan, burn easily
II White Tan with difficulty, burn easily
III White Tan easily but may burn initially
IV Light brown/olive Tan easily, hardly burn
V Brown Tan easily, usually do not burn
VI black Become darker, do not burn
21. Light
• Type (artificial light or UVR)
• Intensity
• Duration of exposure to UVR
Duration of onset & persistence
22. Age of onset
Exposure to photosensitizers
Genetic predisposition (Birth history )
Symptoms (itch,pain,burning)
23. Type of Primary lesion :
Redness
Swelling
Papules
Vesicles
Blisters or Pigmentation
24. Seasonal variation (What time of year does
the problem present— is there any seasonal
variation?
What sort of exposure is required to trigger
the problem?(direct or through window glass)
25. Any post-inflammatory hypo/hyper
pigmentation or scarring
Visceral or neurological symptoms
Connective tissue disease
26. Any evidence of ‘hardening’
Are antihistamines, sunscreen creams, or
clothing protective?
History of eczema
Hx of contact allergy
27. Hx of drugs/chemical
Family history
Hobbies
28. Distribution of lesion
Morphology of lesion
Crusting
Scaring
Hypo/hyper pigmentation
Chronic sun-damage
29. Urticarial EPP and solar urticaria
Papules PLE and Chronic actinic
dermatitis
Vesicles PCT and PLE
43. Recurrent delayed onset abnormal reaction
to sunlight that resolves without scaring
Commonest
Young female
Associated with L.E, Actinic prurigo,
photosensitive psoriasis
Delayed type photosensitivity
44. Spring or early summers
Onset is usually 6hours - 2 days
Mixed papular ,vesiculobullous lesions.
45.
46. Epidermal edema & spongiosis
Vesicle formation
Mild liquefaction degeneration of basal
layer,dense lymphocytic infiltrate in
dermis,edema of papillary dermis and
endothelilal swelling.
47. Blistering eruption affecting the upper
pinnae
Blisters or papules
Boys & men
Occurs after a few days of sun exposure
58. Type 1 hypersensitivity
3rd or 4th decade of life
Females
Urticarial lesions
Within minutes of exposure to UVR
Resolves within 2 hrs
Erythema persists for 24 hrs
59. If lager areas are exposed then systemic
symptoms
(headache,nausea,dizziness,photophobia,wh
eeze)
Solar angio-oedema
2 types
Idiopathic
Secondary to drugs/chemicals
84. Lime, lemon, wild parsley, celery, giant
hogweed, parsnips, carrot greens, figs s walk
Beaches containing meadow grass and
children playing in grassy meadows develop
PPD on the legs; meadow grass contains
Agrimony
85.
86.
87. Perfumes containing oil of bergamot (which
contains bergapten, 5-methoxypsoralen) may
develop streaks of pigmentation only in areas
where the perfume was applied
Especially the sides of the neck