Photobiology and Photosensitivity Disorders Flashcards
1- A 13-year-old boy presents with skin lesions that flare during the spring and summer,especially in temperate climates. Phototesting to both UVA and UVB is abnormal, suggesting that his skin lesions can be provoked by UVB and UVA. This example of phototesting to UVB or UVA is abnormal in approximately two-thirds of patients with which condition?
A. Photorecall reaction to methotrexate
B. Hartnup disease
C. Reticular erythematous mucinosis
D. Actinic prurigo
E. Grover disease
Correct choice: D. Actinic prurigo
Explanation: Photoaggravated dermatoses are conditions in which the primary underlying disease is not caused, but rather exacerbated, by sun exposure, sometimes severely. Phototesting is usually normal, with lupus erythematosus being the exception. Photoaggravated dermatoses include: Hartnup disease, reticular erythematous mucinosis, and Grover disease. Actinic prurigo is triggered by UVR exposure and therefore typically flares during spring and summer, especially in temperate climates. In actinic prurigo, phototesting results are abnormal in approximately two-thirds of patients and cutaneous lesions can be provoked by UVB or UVA. Phototesting in patients taking methotrexate is normal. 1 – Methotrexate can cause a photorecall reaction which develops 3-5 days after UV radiation. Phototesting is normal in patients taking methotrexate. 2 – Hartnup disease is a photoaggravated dermatosis. Phototesting is normal. 3 – Reticular erythematous mucinosis is a photoaggravated dermatosis. Phototesting is normal. 5 – Grover’s disease is a photoaggravated dermatosis. Phototesting is normal.
2- An 8 year old native American boy presents to your clinic with erythematous edematous plaques and papules with hemorrhagic crusts on his face, neck, and lower arms. You also notice pitted linear scars in the same anatomic locations, as well as cheilitis and conjunctivitis. What is the best systemic treatment for this boy?
A. Hydroxychloroquine
B. Chloroquine
C. Quinacrine
D. Thalidomide
E. Azathioprine
Correct choice: D. Thalidomide
Explanation: The stem describes a typical case of actinic prurigo, which is similar to polymorphous light eruption but seen mainly in native American children and usually begins before age 10. It is often worse in spring and summer. It tends to improve or resolve in adolescence. Treatment consists of photoprotection and topical steroids. Thalidomide is the only effective systemic agent.
The remaining answer choices are not helpful in the treatment of actinic prurigo. Reference: PMID: 24891055
3- Which of the following are true regarding actinic reticuloid?
A. Affects young women
B. CD4+ T cells in lesional skin
C. Is a malignant condition
D. Positive photo patch testing is rare
E. Generalized lymphadenopathy common
Correct choice: E. Generalized lymphadenopathy common
Explanation: Actinic reticuloid is a type of chronic actinic dermatitis. Ive et al. introduced the disease as a severe dermatosis with no apparent photoallergen. It generally affects elderly males and is characterized by infiltrated erythematous plaques on an eczematous background in exposed sites with lymphadenopathy.
Histopathologically, 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. Positive photo patch testing is common. It generally affects elderly males.
4- Which of the following most commonly causes a photoallergic contact dermatitis that is exacerbated by UVA radiation?
A. Ascorbic acid
B. Titanium dioxide
C. Oxybenzone
D. Zinc oxide
E. Dihydroxyacetone
Correct choice: C. Oxybenzone
Explanation: Oxybenzone is the most common sunscreen agent causing photoallergic contact dermatitis. Patients sensitive should be instructed to avoid sunscreens containing oxybenzone. UVA is more of a factor in causing photoallergic reactions than UVB.
Ascorbic acid is another name for Vitamin C and rarely causes a photoallergy. Titanium dioxide and zinc oxide are physical blockers that do not cause photoallergies. Dihydroxyacetone is the active ingredient in sunless tanners and is not a common cause of photoallergies.
5- The active spectrum for cutaneous vitamin D3 synthesis is:
A. 200-290nm
B. 290-320nm
C. 320-340nm
D. 340-400nm
E. 400-700nm
Correct choice: B. 290-320nm
Explanation: Vitamin D3 synthesis occurs in response to cutaneous exposure to UVB (Wavelength: 290-320nm). Cutaneous Vitamin D3 production does not occur in response to UVC (200-290nm), UVA2 (320-340nm), UVA1 (340-400nm), or Visible light (400-700nm).
6- Which of the following is true regarding polymorphous light eruption?
A. Usually appears in the eight decade
B. May be a manifestation of a type I hypersensitivity reaction
C. Vesicles and bullae are a common presentation
D. Not all exposed areas show lesions
E. It cannot occur through windowglass
Correct choice: D. Not all exposed areas show lesions
Explanation: Polymorphous light eruption is the most common photodermatosis. Not all exposed areas show lesions, but the same areas are affected year after year. PMLE is an idiopathic disease that usually appears in the first three decades. Pathogenesis is unclear but it may be related to a type IV hypersensitivity reaction. Most lesions are erythematous, pruritic papules. The plaque form is less common, and vesicles and an eczematous dermatitis are rare. It may improve as the summer progresses. It may occur through windowglass, which filters out UVB.
7- Which of the following is true about UVB radiation?
A. Cause of immediate and delayed skin tanning
B. More intense in the winter months
C. Peaks at 10am
D. Decreased with high wind velocity
E. Generally blocked by car window glass
Correct choice: E. Generally blocked by car window glass
Explanation: The UVB band extends from 290 to 320 nm. The UVB spectrum is recognized as the primary cause of sunburn, skin cancer, and other harmful effects on human skin. Notably, window glass filters out ultraviolet wavelengths shorter than 320 nm, so both UVB and UVC are effectively filtered by car window glass. The UVA band extends from 320 to 400 nm. This spectrum is further subdivided into UVA-2 (320 to 340 nm) and UVA-1 (340 to 400 nm). The UVA spectrum is recognized as a cause of immediate and delayed tanning reaction of skin, and several other effects including photoaging, skin photosensitization, and immunosuppression. UVC radiation comprises wavelengths shorter than 290 nm (from 200 to 290 nm). UVB radiation is more intense during summer months compared to winter months and peaks during midday hours. It has been postulated that physical factors such as high temperature, high humidity, and wind can all increase susceptibility to UV-induced carcinogenesis.
8- You are called to evaluate a patient that recently returned from a trip to Mexico with these cutaneous findings (photosensitivity). Upon further questioning, he reports being on oral doxycycline (?drug-induced) for Lyme disease for the past 14 days. What is the major contributor of this cutaneous reaction?
A. UVA
B. UVA1
C. UVB
D. UVC
E. Visible Light
Correct choice: A. UVA
Explanation: UVA (315-400 nm) is the major contributor to drug-induced photosensitivity. Common drugs causing phototoxic eruptions include tetracyclines, furosemide, thiazides,
sulfonamides, NSAIDS, oral retinoids, amiodarone, and phenothiazines. UVB (290-315 nm) is more erythemogenic and associated with photocarcinogenesis.
9- The drug of choice for erythema nodosum leprosum has also been very effective for a majority of patients with which immune-mediated photodermatosis:
A. Actinic prurigo
B. Chronic actinic dermatitis
C. Solar urticaria
D. Hydroa vacciniforme
E. Polymorphous light eruption
Correct choice: A. Actinic prurigo
Explanation: Thalidomide, the drug of choice for erythema nodosum leprosum, has been very effective for a majority of patients with actinic prurigo.
10- Which of the following is TRUE regarding Ultraviolet A light?
A. Its wavelength spans 290-320nm
B. It is responsible for delayed melanogenesis
C. It is involved in Vitamin D3 production
D. It penetrates window glass
E. It plays a major role in carcinogenesis
Correct choice: D. It penetrates window glass
Explanation: UVA light penetrates window glass (UVB does not). The remaining answer choices are true regarding UVB light.
11- solar urticaria can be provoked by which of the following light sources?
A. Visible light and UVB
B. UVA II only
C. UVA I and II
D. UVB and UVA (most severely UVB)
E. UVA, visible light and less by UVB
Correct choice: E. UVA, visible light and less by UVB
Explanation: Solar urticaria can be brought on by UVB or UVA or visible light or combinations of those wavelengths. Solar urticaria can be brought on by UVB or UVA or visible light or combinations of those wavelengths.
12- Lichen planus-like lesions on sun-exposed areas may be seen in patients being treated with:
A. Statins
B. Ketoprofen
C. Quinolones
D. Hydrochlorothiazide
E. Acetaminophen
Correct choice: D. Hydrochlorothiazide
Explanation: Lichenoid medication photosensitivity, with LP-like lesions on sun-exposed areas has been associated with treatment with HCTZ, β-blockers, ACE inhibitors, antimalarials, gold salts, TNF-α inhibitors, NSAIDs, penicillamine, and quinidine. The other listed medications are not associated with lichenoid medication photosensitivity.
13- In regards to cutaneous UV exposure, chromophores of the epidermis include all of the following EXCEPT:
A. Nucleic acid
B. Protein
C. Melanin
D. Porphyrins
E. Urocanic acid
Correct choice: D. Porphyrins
Explanation: Porphyrins (and hemoglobin) are chromophores of the dermis.
14- A 22 year old female presents with the shown lesion. Although unchanging and asymptomatic, she is inquiring about possible laser surgery to lighten the lesion’s appearance. What is the wavelength of light for the most appropriate laser system to choose for this patient?
A. 532 nm
B. 595 nm
C. 755 nm
D. 1064 nm
E. 10,600 nm
Correct choice: C. 755 nm
Explanation: This lesion shows a cafe au lait macule. As the target chromophore is the melanin, the laser system selected should be able to selectively target melanin. While the KTP (532nm), PDL (595nm), Alex (755nm) and Nd:YAG (1064nm) systems can all target melanin, the Alex system is the preferred laser to target melanin in patients with Type I-III skin types, given its efficacy and safety. A nanosecond or picosecond system should be used.
10,600nm does not effectively target melanin.
15- Oral PUVA has been used to treat all of the following diseases EXCEPT:
A. Cutaneous T cell lymphoma
B. Mastocytosis
C. Graft-versus-host disease
D. Generalized granuloma annulare
E. Systemic Lupus Erythematosus
Correct choice: E. Systemic Lupus Erythematosus
Explanation: PUVA has been reported to have helped patients with all the diseases listed except SLE. Any form of light therapy should be carefully and strongly contemplated before initiation in patients with SLE due to the photo-induced nature of the condition.
16- A 9-year-old Native American boy presents with chronic cheilitis and conjunctivitis that has been present since childhood. He has crusted papules and nodules on his extensor surfaces that are intensely pruritic. Which of the following is the most likely diagnosis?
A. Lip-licker’s dermatitis
B. Photoaggravated atopic dermatitis
C. Polymorphous light eruption
D. Hydroa vacciniforme
E. Actinic prurigo
Correct choice: E. Actinic prurigo
Explanation: Actinic prurigo is a severe condition common in Native Americans, often presenting with cheilitis and conjunctivitis. It can occur in all races and usually has a childhood onset. It often
resolves by adolescence yet can persist indefinitely. Lesions are intensely pruritic, crusted papules or nodules in sun-exposed sites.
1 – Lip-licker’s dermatitis (or eczema) is an atopic cheilitis involving both the vermilion lip and surrounding skin. Eczema of the lips is common in atopic dermatitis patients, especially during the winter. It is characterized by dryness of the vermilion lips, sometimes with peeling and fissuring, and may be associated with angular cheilitis. These patients try to moisten their lips by licking, which in turn may irritate the skin around the mouth.
2 – Photoaggravated atopic dermatitis is not directly caused by UVR exposure but may be worsened by it. Widespread involvement can be confused with chronic actinic dermatitis, however phototest results are negative in photoaggravated atopic dermatitis.
3 – Polymorphous light eruption is the most common dermatosis. It is characterized by papules, vesicles or plaques within hours of sun exposure and lasts for a few days. The action spectra is UVB, UVA, and rarely visible light. It is managed by photoprotection and narrow band UVB. Occasionally, brief courses of topical or oral corticosteroids for acute attacks.
4 – Hydroa vacciniforme is a very rare, childhood-onset photodermatosis. It is characterized by papules and plaques that develop umbilicated vesiculation, followed by hemorrhagic crusting (often severe) and varioliform scarring. Epstein-Barr viral infection has been detected in a number of patients. Management requires careful photoprotection and perhaps low-dose phototherapy.
17- Which of the following statements is true regarding pseudoporphyria?
A. Porphyrins are commonly normal
B. It has not been associated with furosemide
C. Clinically it is easily distinguishable from porphyria cutanea tarda
D. It has not been associated with naproxen
E. UV protection is not helpful for treatment
Correct choice: A. Porphyrins are commonly normal
Explanation: Pseudoporphyria is a phototoxic reaction that clinically and histologically resembles porphyria cutanea tarda. In pseudoporphyria, however, there is typically no porphyrin abnormality. Pseudoporphyria has been associated with numerous medications, including NSAIDs (naproxen, piroxicam), nalidixic acid, tetracyclines, amiodarone, furosemide, and HCTZ, isotretioin, and sulfonamides. Clinically, it is commonly indistinguishable from PCT. In addition to withdrawal of the offending agent, UV protection is helpful in the treatment of pseudoporphyria.
18- PUVA bulbs have a peak output in which wavelength range?
A. 350-360 nm
B. 360-370 nm
C. 280-320 nm
D. 280-290 nm
E. 400-760 nm
Correct choice: A. 350-360 nm
Explanation: The PUVA bulbs have a peak output in the 350-360 nm range. Fluorescent UVA bulbs used for phototesting or PUVA therapy have a peak emission at 352 nm.
19- How does photodynamic therapy lead to cell apoptosis/necrosis on a cellular level?
A. Formation of reactive oxygen species
B. Inhibition of pyrimidine nucleotide synthesis
C. Neutrophil-mediated, antibody-dependent cellular cytotoxicity
D. Proteosome inhibition
E. Heat shock proteins
Correct choice: A. Formation of reactive oxygen species
Explanation: The correct answer is the formation of reactive oxygen species (Choice 1). For photodynamic therapy (PDT), a photosensitizer is converted to protoporphyrin IX within cells. When protoporphyrin IX is irradiated with an appropriate wavelength of light, it is first activated to singlet state and then a triplet state. The triplet state of the photosensitizer reacts with oxygen to form reactive oxygen species (ROS), most notably singlet state oxygen, which causes direct tissue damage. Inhibition of pyrimidine nucleotide synthesis (Choice 2), neutrophil-mediated antibody- dependent cellular cytotoxicity (Choice 3), proteosome inhibition (Choice 4), heat shock proteins (Choice 5) are not involved in the mechanism of PDT on a cellular level.
20- Which of the following genodermatoses is worsened by sunlight?
A. Neurofibromatosis
B. Tuberous sclerosis
C. Cowden syndrome
D. Rothmund-Thompson syndrome
E. Job syndrome
Correct choice: D. Rothmund-Thompson syndrome
Explanation: Many genodermatoses can be exacerbated by sunlight including Darier’s, Kindler, Rothmund Thompson, Hartnup (pellagra changes). The other genodermatoses listed are not worsened by sunlight.
21- A 52-year-old man presents with pruritic, eczematous plaques and papules with lichenification on his dorsal hands, extensor forearms, V-neck and face that have been persistent for 15 years. There is a sharp cutoff at the line of his shirt. The patient also has a coexisting allergy to daisies. What is the most likely diagnosis of his skin condition?
A. Atopic dermatitis
B. Chronic actinic dermatitis
C. Systemic lupus erythematosus
D. Mycosis fungoides
E. Actinic prurigo
Correct choice: B. Chronic actinic dermatitis
Explanation: Chronic actinic dermatitis is characterized by a chronic eczematous eruption (acute, subacute or chronic lichenified) or pseudolymphomatous lesions in sun-exposed areas. It is most common in men over 50 years of age and commonly affects older men of any race. Positive patch or photopatch tests are common. Coexisting allergic contact sensitivity to plant antigens, fragrances or topical medications is common. The CAD eruption is pruritic, patchy or confluent, and the eczematous lesions can be acute, subacute or chronic in nature; the latter is frequently associated with lichenification. In severely affected individuals, scattered or widespread, erythematous, shiny, infiltrated, pseudolymphomatous papules or plaques may be present in severely affected individuals.
1 – Atopic dermatitis is not the best answer choice, however it is a photoaggravated dermatitis. Chronic actinic dermatitis can be distinguished from atopic dermatitis by the natural history and clinical appearance of the cutaneous lesions.
3 – Systemic lupus erythematosus is not the best answer choice, however it is a photoaggravated dermatosis. Chronic actinic dermatitis can be distinguished from systemic lupus erythematosus by the natural history and clinical appearance of the cutaneous lesions.
4 – Mycosis fungoides (cutaneous T-cell lymphoma and Sezary syndrome) are photoaggravated dermatoses and is a possible differential diagnosis but is not the best single choice answer. Chronic actinic dermatitis can be distinguished from mycosis fungoides by the natural history and clinical appearance of the cutaneous lesions. Very rarely, a patient with severe CAD features may have a histologic diagnosis suggestive of cutaneous T-cell lymphoma. Primary CTCL should be considered if apparent CAD is totally refractory to treatment.
5 – Actinic prurigo is seen most commonly in Native Americans; females > males. It may present with cheilitis and conjunctivitis, and has a childhood onset. Lesions are chronic and persistent throughout childhood but often fade in adolescence.
22- Lesions of polymorphous light eruption (PMLE) typically appear:
A. About one hour after exposure
B. Hours to days after exposure
C. Days to two weeks after exposure
D. 15-30 minutes after exposure
E. Immediately
Correct choice: B. Hours to days after exposure
Explanation: The history of a delay of several hours to several days after exposure is important to the diagnosis.
23- Which of the following drugs is not commonly known to produce photosensitivity?
A. Quinidine
B. Sulfonylureas
C. Griseofulvin
D. Doxycycline
E. Mycophenolate Mofetil
Correct choice: E. Mycophenolate Mofetil
Explanation: Mycophenolate mofetil is not known to cause photosensitivity. Quinidine, sulfonlyureas, griseofulvin, and doxycycline are all known to cause photosensitivity.
24- Which of the following should NOT be included on the differential diagnosis of this patient?
A. Photoallergic contact dermatitis
B. Airborne contact dermatitis
C. Chronic actinic dermatitis
D. Drug photosensitivity
E. Solar urticaria
Correct choice: E. Solar urticaria
Explanation: Solar urticaria produces erythematous, edematous papules/plaques, not erythematous, eczematous patches/plaques, in sun exposed areas. Photoallergic contact, airborne contact, chronic actinic dermatitis, and drug photosensitivity can all result in erythematous, eczematous patches in sun exposed areas. Subtle clues may help distinguish them such as involvement of the submental area in an airborne contact dermatitis.
25- What dose phototesting for MED B show in a patient with this condition (chronic actinic dermatitis):
A- MED B is is not necessary to measure
B- increase in MED B
C- no change in MED B
D- unpredictable change in MED B
E- Decrease in MED B
Correct choice: E - Decrease in MED B
Explanation: This is CAD which is the only photosensitive disorder that has decreased in MED B.
26- Currently the most common cause of photoallergic contact dermatitis is:
A. Halogenated salicylanilides
B. Musk ambrette
C. 6-methylcoumarin
D. Sunscreens
E. Mercaptobenzothiazole
►D
Halogenated salicylanilides, musck ambrette and 6-methylcoumarin used to cause most of the cases of photoallergic contact dermatitis. They have been essentially eliminated from soaps and fragrances. Sunscreen ingredients are now the most common cause.
27- Advantages of narrowband UVB over PUVA therapy are the following EXCEPT:
A. Need for protective eyewear
B. No nausea
C. Safe in childhood
D. Safe in pregnancy
E. More effective in treating thick plaques of CTCL
►E
UVB, both narrowband and broadband, is less penetrating into the skin than UVA. Therefore, PUVA is more effective for thick plaques of CTCL. The UVB does not reach to the bottom of the plaques.
28- What mutation is responsible for this clinical presentation in a patient with thyroid dysfunction and chronic candidal infections?
A. AIRE
B. PTEN
C. TRP1
D. fumarate hydratase
E. LYST
►A
APECED syndrome named for the clinical features of autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy and is caused by a mutation in AIRE (autoimmune regulator). 13% of these patient have vitiligo.
29- This patient presented with hyperpigmented streaks after a vacation in the Caribbean. The most likely diagnosis is:
A. PMLE
B. CAD
C. Melasma
D. Phytophotodermatitis
E. Actinic prurigo
►D
Phytophotodermatitis requires exposure to certain plants or fruits followed by sunlight. Parsnips, parsley, figs, limes, celery, bergamot oranges, and others contain psoralens that react with UVA. Initially there is erythema and blistering followed by streaked hyperpigmentation.
30- A patient demonstrates a positive photopatch test to musk ambrette and a lowered MEDB. The correct diagnosis is most likely:
A. PMLE
B. Solar urticaria
C. CAD
D. Actinic prurigo
E. Photoallergic contact dermatitis
►C
Only chronic actinic dermatitis (CAD) has a lowered MEDB. That finding helps distinguish CAD from photoallergic contact dermatitis in which one sees a positive photopatch test also.
31- Which of the following statements regarding phototesting is correct?
A. The UVB MED is performed using narrowband UVB light sources
B. The UVA MED is performed using a narrowband UVA source
C. To test for a visible light reaction, a slide projector is used as a light source
D. Repeated MEDs to UVB or UVA, given to different test sites over several days can be used to reproduce lesions of polymorphous light eruption
E. A single large dose of visible light is the best way to reproduce lesions of polymorphous light eruption
►C
Phototesting is done prior to initiating phototherapy or during provocative induction. To test for a visible light reaction, a slide projector is used as a light source. The other choices are incorrect. The UVB MED and UVA MED is performed using BROADBAND UVB and BROADBAND UVA light sources respectively. Repeated MED’s to UVB or UVA given to the SAME site may be used to reproduce lesions of PMLE. Alternatively a single large dose of UVA or UVB can be used to reproduce PMLE.
-This disease can be brought on by:
A. Visible light
B. UVA II
C. UVA I
D. UVB
E. All of these answers are correct
►E
Solar urticaria can be brought on by UVB or UVA or visible light or combinations of those wavelengths.
33- The best definition for a MED is:
A. The dose of ultraviolet radiation that produces barely perceptible erythema that completely fills the test square
B. The dose of ultraviolet radiation that produces a easily visible “sunburn”
C. The dose of ultraviolet radiation that is one step below the first visible erythema
D. The dose of ultraviolet radiation that produces pronounced erythema that completely fills the test square
E. The dose of ultraviolet radiation that produces bullae that completely fills the test square
►A
An MED is the dose of ultraviolet radiation that produces barely perceptible erythema that completely fills the test square. The remaining options are incorrect.
34- Of the following which one is most characteristic of photoxocity rather than photoallergy?
A. Onset in hours to days
B. Eczematous dermatitis
C. Cross-reactivity to chemically similar agents
D. Often caused by furocoumarins
E. Relatively low incidence
►D
Furocoumarins may cause a phytophotodermatitis that is a phototoxic reaction. Such reactions occurs with high frequency in the population, occur within minutes to hours from exposure, and appear like an exaggerated sunburn. The other answers are common with photoallergy, such as seen with sunscreens, fragrances, and various systemic medications like chlorpromazine.
35- Lichen planus-like lesions on sun-exposed areas may be seen in patients being treated with:
A. Fenofibrate
B. Ketoprofen
C. Quinolones
D. All of these answers are correct
E. None of these answers are correct
►A
Lichenoid medication photosensitivity, with LP-like lesions on sun-exposed areas has been associated with treatment with antimalarials, thiazides, demethylchlortetracycline, fenofibrate, enalapril, quinine, and quinidine.
-Which of the following is not true about UVB radiation?
A. Responsible for sunburn
B. More intense in the summer than winter months
C. Peaks at noon
D. Decreased with high wind velocity
E. Virtually all blocked by car window glass
►D
The UVB band extends from 290 to 320 nm. The UVB spectrum is recognized as the primary cause of sunburn, skin cancer, and other harmful effects on human skin. The UVA band extends from 320 to 400 nm. This spectrum is further subdivided into UVA-2 (320 to 340 nm) and UVA1 (340 to 400 nm). The UVA spectrum is recognized as a cause of immediate and delayed tanning reaction of skin, and several other effects including photoaging, skin photosensitization, and immunosuppression. UVC radiation comprises wavelengths shorter than 290 nm (from 200 to 290 nm). Notably, window glass filters out ultraviolet wavelengths shorter than 320 nm, so both UVB and UVC are effectively filtered by car window glass. UVB radiation is more intense during summer months compared to winter months and peaks during midday hours. It has been postulated that physical factors such as high temperature, high humidity, and wind can all increase susceptibility to UV-induced carcinogenesis.
37- Hereditary PMLE of Native Americans:
A. Is more similar to PMLE than to actinic prurigo
B. Often presents with chelitis and conjunctivitis
C. Is not treated with thalidomide
D. Rarely persists into adulthood
E. All of these answers are correct
►B
Hereditary PMLE of Native Americans is similar to actinic prurigo but persists much more frequently into adulthood. 75% of patients have a positive family history. It presents with a papular, excoriated, eczematous dermatitis that occurs predominantly on the face. Chelitis and conjunctivitis are common. It may be treated with thalidomide.
38- UVA II encompasses which wavelengths ?
A. 290-320 nm
B. 320-400 nm
C. 400-450 nm
D. 320-340 nm
E. 340-400 nm
►D
UVA can be divided into UVA II (320-340 nm) and UVA I (340-400 nm).
39- Which of the following patients would be the most likely to present with chronic actinic dermatitis?
A. A 4 year-old Native American boy
B. A teenage girl
C. A 64 year-old farmer
D. A 32 year-old woman
E. A 32 year-old man
►C
Patients with chronic actinic dermatitis are usually middle-aged to elderly males who present with a chronic eczematous dermatitis in a photodistribution without history of current exposure to a photosensitizer.
40 -Ultraviolet radition has been shown to do all of the following in in vitro and in vivo studies EXCEPT:
A. Alter the ability of antigen-presenting cells to present antigen
B. Suppress the induction of delayed-type hypersensitivity
C. Increase circulating levels of IL-6
D. Decrease circulating levels of IL-1
E. Induce suppressor T-cells
►D
UV-irradiated mice have been shown to have defective antigen presentation and a decreased number of antigen-presenting cells, which prevents a normal delayed-type hypersensitivity response. UVR causes the release of immunosuppressive factors, with induction of suppressor Tcells and increases in circulating levels of cytokines, including IL-1, IL-6, and TNF.
41 -Which of the following hypoglycemics is the most common cause of photosensitivity?
A. Insulin
B. Sulfonylureas
C. Metformin
D. Thiazolidinediones (i.e. rosiglitazone)
E. Piroxicam
►B
The sulfonylurea hypoglycemics for diabetes are the most common type of medication of this class of medications. Piroxicam is not a hypoglycemic agent, but a common NSAID cause of photoallergy.
42- Which of the following is the most common photodermatosis?
A. Hydroa vacciniforme
B. Chronic actinic dermatitis
C. Actinic prurigo
D. Polymorphous light eruption
E. Solar urticaria
►D
Polymorphous light eruption is the most common photodermatosis. It is a idiopathic disease that usually appears in the first three decades of life and is more common in fair-skinned females. The pathogenesis is unclear, but is believed to be related to a type IV hypersensitivity reaction. Most lesions are erythematous pruritic papules, with the plaque form being less common. Lesions appear symetrically on exposed areas after a delay of several hours to several days. Patients with mild disease are treated with sun avoidance and a broad spectrum sunscreen. In more severe cases, hardening and desensitization can be accomplished or antimalarials can be used for resistant cases. For brief, sunny vacations, a short course of prednisone can be helpful. The other options are less common forms of idiopathic photosensitivity disorders.
43- Treatment of CAD might include:
A. UV filters for car windows
B. Broad spectrum sunblock to which the patient is not allergic
C. Incandescent bulbs for home and office lighting
D. PUVA
E. All of these answers are correct
►E
CAD patients are exquisitely sensitive to UVB, often sensitive to UVA, and sometimes sensitive to visible light. Answers a, b, and c are correct because those treatments prevent UV and visible radiation from reaching the patient. PUVA hardens and desensitizes the skin.
44- The portion of the electromagnetic spectrum that produces a particular biologic effect is called the:
A. Action Spectrum
B. Absorption Spectrum
C. Cutaneous Effect Spectrum
D. Effective Spectrum
E. Spectral Activity
►A
The action spectrum is the wavelengths that produce a certain biologic effect. The action spectrum for photosensitivity from exogenous chemicals is usually in the UVA range. The radiation that is absorbed by those chemicals is called their absorption spectrum.
45- Photoonycholysis has been attributed to:
A. Amiodarone
B. Chlorpromazine
C. Quinine
D. Furosemide
E. Tricyclic antidepressants
►C
Photoonycholysis is a manifestation of medication photosensitivity that has been attributed to quinolones, tetracyclines, psoralens, and quinine.
46- Narrow band UVB consists of what wavelength?
A. 300-306nm
B. 308-310nm
C. 311-313nm
D. 312-320nm
E. 320-330nm
►C
Narrowband UVB is much less erythemogenic with regard to physical units (mJ/cm2) than broadband UVB. Narrowband UVB is 311-313nm.
47- A normal MEDB on untanned Caucasian skin ranges from approximately:
A. 2-6 mJ/cm2
B. 15-40 mJ/cm2
C. 20-70 mJ/cm2
D. 70-140 mJ/cm2
E. 140-200 mJ/cm2
►C
The MEDB can vary from institution to institution. In one institution, it may range from 20 -70 mJ/ cm2. In another institution, it may range from 30-90 mJ/cm2.
48 -Which of the following is true regarding actinic prurigo?
A. Lesions generally continue through late adulthood
B. Lesions persist for 1-2 days
C. Lesions never occur on non-sun-exposed areas
D. Cheilitis is frequently seen
E. Thalidomide has been ineffective for the majority of patients
►D
Actinic prurigo is an idiopathic photosensitivity disorder. Lesions are excoriated papules and nodules that begin in childhood and remit in puberty. They can last for several months and may occur on non-sun-exposed areas. Thalidomide has been very effective for treating the majority of patients with actinic prurigo.
49- Actinic prurigo (AP) differs from PMLE in all of the following except:
A. The lesions of AP begin in childhood
B. The lesions of AP occur on all sun-exposed areas
C. Lesions of AP may occur on non-sun exposed areas
D. Cheilitis is common in AP and common in PMLE
E. Outbreaks of AP are not as clearly related to sun exposure
c
►D
Cheilitis is common in actinic prurigo and not a usual accompaniment in PMLE.
50- Which of the following statements about UVR and DNA is correct?
A. UVR alters DNA
B. UVA is much more efficient than UVB in inducing DNA damage
C. Cells from patients with actinic keratoses have more DNA repair capacity than controls
D. UVA is most effective in producing pyrimidine dimer
E. Pyrimidine dimers can not activate oncogenes
►A
UVR alters DNA. UVB is much more efficient than UVA in inducing DNA damage. It can create pyrimidine dimers that may activate oncogenes and lead to cancer. Cells from patients with actinic keratoses have less DNA repair capacity than controls.
51- UVB acts on what compound to form pre-Vitamin D3 ?
A. 5-dehydrocholesterol
B. 9-hydrocholesterol
C. 7-deoxycholesterol
D. 7-dehydrocholesterol
E. DNA
►D
UVB converts 7-dehydrocholesterol in the skin to pre-Vitamin D3, which then thermally isomerizes to form Vitamin D3.
52 -All of the following are true regarding polymorphous light eruption except:
A. Pruritic
B. Abnormal metabolism of arachidonic acid
C. Hardening occurs with subsequent episodes
D. Lesions heal without scarring
E. Anti-Ro antibody positive
►E
Polymorphous light eruption is the most common photodermatosis that is characterized clinically by the abnormal occurrence of pruritic, erythematous, edematous papules following exposure to UV radiation. Lesions heal without scarring. It tends to affect women 2-3x more than men. Positive Anti-ro antibodies should raise the suspicious for subacute cutaneous lupus erythematosus (tends also to be less pruritic).
53- Absorption of UV radiation generates singlet oxygen in the skin by which chromophore?
A. Melanin
B. Urocanic acid
C. Keratin
D. Hemoglobin
E. Water
►B
Urocanic acid and DNA are biologically important chromophores. DNA absocrbs uVB directly inducing changes between adjacent pyrimidine bases on one strand of DNA. Cyclopyrimidine dimers, particularly thymine dimers or less commonly (6-4) photoproducts may be generated. Urocanic acid is a second biologically important chromophore in the skin and is a by-product of filaggrin breakdown. One photon of light contains enough energy to generate singlet oxygen.
54- UVB converts 7-dehydrocholesterol in the skin to pre-vitamin D3. What is the catalyst of the next step, the conversion to vitamin D3?
A. Thermal isomerization
B. Enzymatic conversion in the skin
C. Cell mediated conversion
D. No catalyst is needed
E. Enzymatic conversion in the liver
►A
7-dihydrocholesterol is present in the skin and is converted to previtamin D3 by UV in the spectrum of 290-315 nm. The Previtamin D3 then thermally isomerizes to form vitamin D3 which enters the circulation. 1-hydroxylation occurs in the liver and 25-hydroxylation in the kidney resulting in the final form of 1,25-dihydroxyvitamin D3.
55- Which of the following statements about electromagnetic radiation is MOST correct?
A. Electromagnetic radiation can be conceptualized as packets of power called photons
B. The energy of photons is proportional to the wavelength
C. The energy of photons is inversely proportional to the frequency
D. Longer wavelengths penetrate the skin more deeply
E. Electromagnetic radiation is measured in watts
►D
Longer wavelengths penetrate the skin more deeply. Electromagnetic radiation can be conceptualized as packets of ENERGY called photons. The energy of photons is proportional to the FREQUENCY and inversely proportional to WAVELENGTH. Electromagnetic radiation is measured in wavelength.
56- The immunologic effects of UVR include all of the following except:
A. Alteration of Langerhans cell morphology
B. Decrease in IL-1, IL-6, TNF-alpha
C. Suppression of delayed-type hypersensitivity
D. Alteration of lymphocyte population
E. Alteration of Langerhans cell function
►B
UVR causes an increase of circulating cytokines (IL-1, IL-6, TNF-alpha).
57- The xenon arc solar simulator, whose spectrum is in this slide, is useful for:
A. MED-B testing
B. MED-A testing
C. Photopatch testing
D. MED-B testing and MED-A testing
E. MED-B testing, MED-A testing, and Photopatch testing
►D
Solar simulator radiation contains both UVB and UVA in sufficient quantities to be useful for MED- B and MED-A testing. The field size is too small for photopatch testing.
58 -A patient presents with solar urticaria. What tests should be considered initially?
A. ANA
B. ANCA
C. Urinalysis
D. CXR
E. ESR
►A
Solar urticaria is an idiopathic, type I photosensitivity disorder. Rare cases have been associated with erythropoietic protoporphyria (EPP) and lupus erythematosus (LE). Blood tests for LE and appropriate screening for EPP should be performed including ANA, Ro/La, Urine & Stool porphyrins.
59 -The portion of the electromagnetic spectrum that produces a particular biologic effect is known as the:
A. Absorption spectrum
B. Action spectrum
C. Photobiologic spectrum
D. Minimal erythema dose
E. Active spectrum
►B
The action spectrum is the portion of the electromagnetic spectrum that products a particular biologic effect (e.g. erythema, delayed tanning). The absorption spectrum is the portion of the electromagnetic spectrum that is absorbed by a particular absorbing molecule, or chromophore. The
minimal erythema dose is the dose of UV radiatino that produces barely perceptible erythema during phototesting.
60- Which of the following drugs is commonly known to produce photosensitivity?
A. Quinidine
B. Sulfonylureas
C. Griseofulvin
D. All of these answers are correct
E. None of these answers are correct
►D
Quinidine, sulfonlyureas, and griseofulvin are all known to cause photosensitivity.
61- The MPD of Oxsoralen plus UVA is:
A. Measured at 24 hours
B. Equal to one-half the patients MEDA
C. Tested on the patient”s calf or abdomen
D. Helpful in starting PUVA therapy
E. None of these answers are correct
►D
MPD stands for the minimal phototoxic dose. For Oxsoralen plus UVA, the MPD is measured at 48-72 hours. Testing is done on the upper buttock or forearm.
62- The main contributor to erythema of the skin with exposure to the sun is:
A. UVC
B. UVB
C. UVA1
D. UVA2
E. Visible light
►B
UVB in natural sunlight is the main contributor to erythema. UVB erythema reaches a maximum in 6-24 hours. UVA accounts for 15-20% of sunlight erythema despite that there is much more UVA than UVB in sunlight.
63- Which of the following statements is correct regarding antigen presenting cells after UVR exposure?
A. Have increased ability to prime UV-irradiated mice to subcutaneously injected hapten
B. UV-irradiated mice have normal antigen presentation, allowing a normal delayed-type hypersensitivity response
C. There is a decrease in the number of antigen presenting cells
D. APC’s have increased ability to prime UV-irradiated mice to subcutaneously injected protein
E. APC’s have increased ability to prime UV-irradiated mice to applied contactsensitizing agents
►C
APC’s have depressed ability to prime UV-irradiated mice to subcutaneously injected hapten or protein and to applied contact-sensitizing agents. UV-irradiated mice have defective antigen presentation, preventing a normal delayed-type hypersensitivity response. There is a REDUCTION in number of antigen presenting cells.
64- In solar urticaria wheals may be brought on by:
A. UVA
B. UVB
C. UVC
D. Visible light
E. UVA, UVB and Visible light
►E
Some patients react to visible light or UVA or UVB. Others react to combinations of visible light, UVA, and UVB.
65- The UVAII portion of the electromagnetic spectrum extends from:
A. 200-290 nm
B. 290-320 nm
C. 320-400 nm
D. 320-340 nm
E. None of these answers are correct
►D
UVA extends from 320-400nm. UVA is further subdivided into UVAII (320-340nm) and UVA1 (340-400nm).
What is the most likely cause of these lesions on the cheek of this 8 year-old boy?
A. Acne
B. Herpes simplex
C. Varicella
D. Hydroa vacciniforme
E. Polymorphous light eruption
►D
Hydroa vacciniforme is a rare photodermatosis of childhood which occurs on areas of sun- exposed skin. The lesions leave depressed and atrophic scars. The condition tends to spontaneously resolve in adulthood.
