Photodisorders Flashcards
What is the most common photodermatosis?
PMLE
Who usually get’s PMLE?
fair-skinned women, usually in their first 3 decades
What type of rxn is thought to underly PMLE?
Type IV hypersensitivity rxn
What is the clinical presentation of PMLE?
Erythematous pruritic papules or plaques appear symmetrically on sun-exposed areas (forearms, chest) several hours to several days after sun exposure
What is the key distinguisher between PMLE and solar urticaria?
Solar urticaria appears quickly, usually within 10-30 minutes as compared to the several hours to days after sun exposure for PMLE
Do PMLE lesions appear in the same location each year?
Yes, same location year and year
Are the morphologies the same for PMLE each time the rash occurs?
NO, so the location is the same but the morphology varies
What is the histology of PMLE?
lymphistiocytic infiltrate around the superficial & deep vascular plexuses +/- subepidermal edema
If you were to perform phototesting and photpatch testing on someone for PMLE what would be the results?
Negative -Repeated doses of UV radiation (UVA > UVB) over several days or a single large multiple MEDA or MEDB dose may trigger PMLE
What type of UVR is more most likely to trigger PMLE?
UVA
What is the treatment of PMLE?
Sun avoidance, UVA/UVB sunscreen, hardening & desensitization (NBUVB, UVB + UVA, or PUVA), antimalarials, short-course prednisone
Epidemiology of Actinic prurigo?
Children, girls> boys, begins in childhood and remits during puberty -Most common in Native Americans, especially Mestizo
Is Actinic prurigo a chronic disorder?
It is present during childhood then remits during puberty
What HLA subtype is associated with actinic prurigo?
HLA-DR4
When is actinic prurigo worst?
During the summer
Clinical of actinic prurigo?
Excoriated papules and nodules +/- cheilitis on all sun-exposed areas (sometimes non-sun-exposed areas)
- Conjunctivitis
- Cheilitis common in Native Americans; cheilitis may be only manifestation in 30% of Mestizos
- May persist for months
Histology of actinic prurigo?
spongiosis, acanthosis, dermal perivascular mononuclear infiltrate with occasional eosinophils; NO papillary edema
What would be the results of phototesting in actinic prurigo?
It would be abnormal in 2/3 –> most react to UVB>UVA
What type of UVR flairs actinic prurigo most?
UVB
Tx for actinic prurigo?
Manage like PMLE (topical steroids or tacrolimus = 1st line; NBUVB or PUVA = 2nd line); Thalidomide effective (anti-TNF that modulates the release of IFN-ϒ from CD3+ cells) for resistant dz
What is the difference between actinic prurigo and hereditary PMLE of Native Americans?
Presentation similar to actinic prurigo but persists into adulthood.
What percentage of patients with hereditary PMLE of Native Americans have a + family hx?
75%
What is the clinical of hereditary PMLE of Native Americans?
Papular, excoriated, eczematous dermatitis that occurs predominantly on the face
Conjunctivitis and cheilitis is common
In what population is hydroa vaccinforme most common in?
Children (rare)
Clinical presentation of hydroa vaccinforme?
Stinging erythematous macules on face & dorsal hands within hours of sunlight Progress to tender umbilicated vesicles on sun-exposed areas Resolves in 1-6 weeks with crusting followed by pock-like scars
What conditions is hydroa vaccinforme a/w?
Association with EBV & NK-cell lymphoma or hemophagocytic syndrome
How do you tx hydroa vaccinforme?
Treat with photoprotection; usually refractory to txs; can try UVB, PUVA, beta-carotene, antimalarials, thalidomide, cyclosporine, fish oil
What is the histology of hydroa vaccinforme?
Superficial orthokeratosis, spongiosis, irregular acanthosis, epidermal degeneration, and minimal perivascular chronic inflammatory cell infiltration in the upper dermis
What type of photosensitivity is solar urticaria?
type I photosensitivity
Clinical of solar urticaria?
Widespread whealing may result in headache, nausea, wheezing, faintness, and syncope
How long does solar urticaria usually last?
Many years
What types of light are pts with solar urticaria sensitive to?
Some patients react with wheals to either visible light or UVA or UVB. Others react to both UVA and visible radiation. Some react to both UVB and UVA, and some patients react to UVB, UVA, and visible radiation.
Tx for solar urticaria?
Treatment includes sun avoidance and protection, and H-1 antihistamines may be of partial benefit.
What is the time of onset for solar urticaria?
10-30 minutes after sun exposure (UVA, UVB, and visible light
How long do the lesions of solar urticaria last after onset?
Usually ~ 1 hr after exposure
What areas do the lesions favor?
Sun-exposed areas, but face and hands may not be involved due to hardening and desensitization
What disease can solar urticaria be a/w in 20-50% of cases?
Atopic dermatitis
What must you test for due to rare a/w solar urticaria?
LE and erythropoietic protoporphyria
Epi of chronic actinic dermatitis?
Middle-aged to elderly males, often who are outdoor workers with known prior photo-allergic or allergic contact dermatitis (Compositae, sunscreens)
What is the clinical of chronic actinic dermatitis?
Chronic eczematous dermatitis in photodistribution
Relatively spares upper lids, post-auricular regions, infranasal area, submental area, & finger webs
Sometimes non-sun-exposed areas affected
Pathogenesis of chronic actinic dermatitis?
Believed to begin as photoallergic contact dermatitis or drug photosensitivity that persists (type IV hypersensitivity to allergen)
Histology of chronic actinic dermatitis?
Histology: usually mimics chronic eczema, but may look like MF with atypical mononuclear cells or circulating Sezary cells
What does photo testing show in chronic actinic dermatitis?
Phototesting reveals markedly diminished MEDB +/- diminished MEDA & lowered threshold to shorter wavelength visible light (blue-violet spectrum)
Treatment of chronic actinic dermatitis?
Sun avoidance, broad-spectrum sunscreen, incandescent bulbs, steroids, azathioprine, cyclosporine, MMF, PUVA with risk of eliciting dz
Is chronic actinic dermatitis or actinic reticuloid considered a malignant or pre-malignant condition?
Actinic reticuloid is a type of chronic actinic dermatitis.
It may resemble cutaneous T cell lymphoma.
However, there is a trend towards a lower CD4+/CD8+ ratio. It is not considered a premalignant condition.
What medications can cause photo-onycholysis?
Quinolones, tetracyclines, psoralens and quinine can cause photoonycholysis.
What do you need to consider in a patient with vitiligo, thyroid dysfunction and candida infections?
APECED (autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy) syndrome, a mutation in AIRE. 13% of patients have vitiligo.
What is a photo-allergic reaction?
Photoallergic reactions: are immunologically mediated, occur only in predisposed individuals, rarely occur on the first exposure to the chemical, are called “photoreactive” if they produce damage through reactive oxygen species, resolve with hyperpigmentation
Clinical difference between a phototoxic rxn and photoallergic rxn?
Phototoxic = exaggerated sunburn
Photoallergic rxn = Eczematous dermatitis in sun-exposed areas
Difference in pathogensis between phototoxic rxn and photoallergic rxn?
Phototoxic rxn = non-immunologic
Photoallergic rxn = Delayed type IV hypersensitivity (doesn’t occur on first exposure)
Most common photoallergic drug?
Sunscreens (benzophenone-3 and Oxybenzone; PABA, cinnamates, salicylates), musk ambrette, phenothiazines (chlorpromazine, promethazine), HCTZ, Statins, sulfonamides, dapsone, griseofulvin, quinidine, sulfonylureas (glipizide, glyburide)
What medications can cause blue-gray pigmentation photosensitivity?
Amiodarone, chlorpromazine, and TCA antidepressants
What medications can cause photo-onycholysis?
Quinolones, tetracyclines, psoralens, and quinine
What medications are associated with the photosensitivity pseudoporphyria (PCT w/ normal porphyrins)
Tetracyclines, nalidixic acid, amiodarone, furosemide, and ketoprofen
What drugs are associated with the photosensitivity reaction lichenoid eruption w/ LP-like lesions on sun-exposed areas?
Antimalarials, thiazides, demethylchlortetracycline, fenofibrate, enalapril, and quinine, quinidine
What type of UVB therapy is most effective for psoriasis, atopic dermatitis, and vitiligo?
narrowband UVB (311-312nm)
What type of phototherapy is safe in children and pregnancy?
Narrowband UVB
What is photophoresis work?
WBCs and plasma are separated from RBCs, then the RBCs are returned to the patient. The extracted WBCs are irradiated with UVA after 8-MOP then returned w/ plasma to the patient’s arm.
What type of hypersensitivity reaction is suppressed by UV irradiation?
UV-radiation causes decreased APCs & defective antigen presentation, which prevents a normal delayed-type IV hypersensitivity rxn
What is a phototoxic reaction?
Phototoxic reaction: appears as an exaggerated sunburn with erythema and sometimes blistering, resolving with hyperpigmentation. It is a nonimmunologic reaction that could occur in all individuals given enough of the chemical and enough UVR. It can occur on the first exposure to the chemical and the UVR. Phototoxic reactions that produce damage through reactive oxygen species are called “photodynamic.”
