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Dermatology Board Prep > DERM (06) Disorders Due to Physical Agents > Photodisorders > Flashcards

Photodisorders Flashcards

1
Q

What is the most common photodermatosis?

A

PMLE

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2
Q

Who usually get’s PMLE?

A

fair-skinned women, usually in their first 3 decades

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3
Q

What type of rxn is thought to underly PMLE?

A

Type IV hypersensitivity rxn

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4
Q

What is the clinical presentation of PMLE?

A

Erythematous pruritic papules or plaques appear symmetrically on sun-exposed areas (forearms, chest) several hours to several days after sun exposure

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5
Q

What is the key distinguisher between PMLE and solar urticaria?

A

Solar urticaria appears quickly, usually within 10-30 minutes as compared to the several hours to days after sun exposure for PMLE

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6
Q

Do PMLE lesions appear in the same location each year?

A

Yes, same location year and year

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7
Q

Are the morphologies the same for PMLE each time the rash occurs?

A

NO, so the location is the same but the morphology varies

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8
Q

What is the histology of PMLE?

A

lymphistiocytic infiltrate around the superficial & deep vascular plexuses +/- subepidermal edema

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9
Q

If you were to perform phototesting and photpatch testing on someone for PMLE what would be the results?

A

Negative -Repeated doses of UV radiation (UVA > UVB) over several days or a single large multiple MEDA or MEDB dose may trigger PMLE

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10
Q

What type of UVR is more most likely to trigger PMLE?

A

UVA

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11
Q

What is the treatment of PMLE?

A

Sun avoidance, UVA/UVB sunscreen, hardening & desensitization (NBUVB, UVB + UVA, or PUVA), antimalarials, short-course prednisone

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12
Q

Epidemiology of Actinic prurigo?

A

Children, girls> boys, begins in childhood and remits during puberty -Most common in Native Americans, especially Mestizo

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13
Q

Is Actinic prurigo a chronic disorder?

A

It is present during childhood then remits during puberty

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14
Q

What HLA subtype is associated with actinic prurigo?

A

HLA-DR4

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15
Q

When is actinic prurigo worst?

A

During the summer

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16
Q

Clinical of actinic prurigo?

A

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
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17
Q

Histology of actinic prurigo?

A

spongiosis, acanthosis, dermal perivascular mononuclear infiltrate with occasional eosinophils; NO papillary edema

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18
Q

What would be the results of phototesting in actinic prurigo?

A

It would be abnormal in 2/3 –> most react to UVB>UVA

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19
Q

What type of UVR flairs actinic prurigo most?

A

UVB

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20
Q

Tx for actinic prurigo?

A

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

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21
Q

What is the difference between actinic prurigo and hereditary PMLE of Native Americans?

A

Presentation similar to actinic prurigo but persists into adulthood.

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22
Q

What percentage of patients with hereditary PMLE of Native Americans have a + family hx?

A

75%

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23
Q

What is the clinical of hereditary PMLE of Native Americans?

A

Papular, excoriated, eczematous dermatitis that occurs predominantly on the face

Conjunctivitis and cheilitis is common

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24
Q

In what population is hydroa vaccinforme most common in?

A

Children (rare)

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25
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
26
What conditions is hydroa vaccinforme a/w?
Association with EBV & NK-cell lymphoma or hemophagocytic syndrome
27
How do you tx hydroa vaccinforme?
Treat with photoprotection; usually refractory to txs; can try UVB, PUVA, beta-carotene, antimalarials, thalidomide, cyclosporine, fish oil
28
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
29
What type of photosensitivity is solar urticaria?
type I photosensitivity
30
Clinical of solar urticaria?
Widespread whealing may result in headache, nausea, wheezing, faintness, and syncope
31
How long does solar urticaria usually last?
Many years
32
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.
33
Tx for solar urticaria?
Treatment includes sun avoidance and protection, and H-1 antihistamines may be of partial benefit.
34
What is the time of onset for solar urticaria?
10-30 minutes after sun exposure (UVA, UVB, and visible light
35
How long do the lesions of solar urticaria last after onset?
Usually ~ 1 hr after exposure
36
What areas do the lesions favor?
Sun-exposed areas, but face and hands may not be involved due to hardening and desensitization
37
What disease can solar urticaria be a/w in 20-50% of cases?
Atopic dermatitis
38
What must you test for due to rare a/w solar urticaria?
LE and erythropoietic protoporphyria
39
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)
40
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
41
Pathogenesis of chronic actinic dermatitis?
Believed to begin as photoallergic contact dermatitis or drug photosensitivity that persists (type IV hypersensitivity to allergen)
42
Histology of chronic actinic dermatitis?
Histology: usually mimics chronic eczema, but may look like MF with atypical mononuclear cells or circulating Sezary cells
43
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)
44
Treatment of chronic actinic dermatitis?
Sun avoidance, broad-spectrum sunscreen, incandescent bulbs, steroids, azathioprine, cyclosporine, MMF, PUVA with risk of eliciting dz
45
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.**
46
What medications can cause photo-onycholysis?
Quinolones, tetracyclines, psoralens and quinine can cause photoonycholysis.
47
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.
48
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
49
Clinical difference between a phototoxic rxn and photoallergic rxn?
Phototoxic = exaggerated sunburn Photoallergic rxn = Eczematous dermatitis in sun-exposed areas
50
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)
51
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)
52
What medications can cause blue-gray pigmentation photosensitivity?
Amiodarone, chlorpromazine, and TCA antidepressants
53
What medications can cause photo-onycholysis?
Quinolones, tetracyclines, psoralens, and quinine
54
What medications are associated with the photosensitivity pseudoporphyria (PCT w/ normal porphyrins)
Tetracyclines, nalidixic acid, amiodarone, furosemide, and ketoprofen
55
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
56
What type of UVB therapy is most effective for psoriasis, atopic dermatitis, and vitiligo?
narrowband UVB (311-312nm)
57
What type of phototherapy is safe in children and pregnancy?
Narrowband UVB
58
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.
59
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
60
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."

DERM (06) Disorders Due to Physical Agents (2 decks)

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