Lasers

Question 1

A 45-year-old woman is being evaluated because of discrete, red, facial capillaries that she would like to have removed. Which of the following lasers is most appropriate to ablate the vessels?

A ) KTP (532-595 nm)

B ) Q-switched ruby (694 nm)

C ) Nd:YAG (1064 nm)

D ) Er:YAG (2940 nm)

E ) Carbon dioxide (10,600 nm)

Answer 1

The correct response is Option A.

The 532-595 nm wavelength is the most appropriate choice, as it has the highest affinity for the vessels and can be more effective with the appropriate settings. Carbon dioxide and erbium lasers are both ablative lasers with a higher affinity for water. The 1064-nm laser can be used for hair reduction or collagen stimulation but works on the deeper layers and is more specific for darker pigmentation of vessels, such as blue. It can be used for vessel reduction in the leg; however, facial vessels are more superficial and often more red than blue in coloration. The 694nm laser would not be the first-line laser for this treatment.

Question 2

Which of the following laser wavelengths has the greatest affinity for water?

(A) 585 nm
(B) 1064 nm
(C) 1320 nm
(D) 2940 nm
(E) 10,600 nm

Answer 2

The correct response is Option D.

The erbium:YAG (Er:YAG) laser emits light at a wavelength of 2940 nanometers (nm) and is absorbed by water within the epidermis a minimum of 10 times more efficiently than the carbon dioxide laser. Its mechanism of action involves photomechanical injury to the targeted tissue.

The 585-nm pulsed-dye laser is used in the treatment of cutaneous vascular lesions.

The lesser-energy, variable pulsed-width frequency, double Q-switched Nd:YAG laser and the higher-energy, millisecond pulsed Nd:YAG laser both have a wavelength of 1064 nm. The double Q-switched Nd:YAG laser is appropriate for the removal of hair or tattoos, and the millisecond pulsed Nd:YAG laser is indicated for treatment of vascular lesions.

The 1320-nm wavelength is incorporated by many nonablative lasers that stimulate collagen production within the dermis. Although the target of these 1320-nm lasers is water, they have 50% less affinity for water than the Er:YAG laser.

The carbon dioxide laser emits light at a wavelength of 10,600 nm. In contrast to the photomechanical action of the Er:YAG laser, the carbon dioxide laser produces photothermal injury. In addition, it has less specificity for its target, resulting in greater collateral injury, including greater contraction of the skin and dermis and increased collagen remodeling. As a result, recovery time is prolonged, and the risk for hyperpigmentation and other associated complications is greater.

Question 3

A 54-year-old woman with Fitzpatrick Type III skin plans to undergo Er:YAG laser
(2940 nm) resurfacing to improve the appearance of periorbital rhytides. Prior to
treatment, the plastic surgeon recommends a topical agent that inhibits enzymatic
conversion of tyrosine to dihydroxyphenylalanine. Which of the following agents
did the surgeon most likely discuss?
A ) Brimonidine
B ) Fluocinolone acetonide
C ) Hydroquinone
D ) Tretinoin
E ) Zinc oxide

Answer 3

The correct response is Option C.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with
over 4.6 million cases performed annually. This increase has led to expansion of different
types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed
since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium
aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used
to target actinic skin damage and moderate to heavy rhytides.
Post-inflammatory hyperpigmentation (PIH) is a common sequela of laser resurfacing
procedures. Pretreatment with various topical agents can optimize the skin, decreasing the
risk for this well-known adverse event. Hydroquinone decreases melanin production by
enzymatically inhibiting the conversion of tyrosine to dihydroxyphenylalanine.
Tretinoin promotes cornified cell detachment and enhances shedding. It also increases mitotic
activity, thereby increasing loosely adherent corneocytes turnover. Tranexamic acid is a
synthetic derivative of the amino acid lysine and binds the five lysine binding sites on
plasminogen. This inhibits plasmin formation and displaces plasminogen from the fibrin
surface. In melasma, the hypothesized mechanism of action of tranexamic acid includes the
shrinkage of dermal vasculature and decreased melanin synthesis by altering the interaction
of keratinocytes and melanocytes and decreasing tyrosinase activity. Fluocinolone acetonide
is a potent corticosteroid that is often used in conjunction with tretinoin and hydroquinone to
treat pre-existing PIH and/or for pretreatment of the skin prior to laser resurfacing. By itself,
fluocinolone does not have the aforementioned mechanism of action. Brimonidine gel,
originally approved for the treatment of facial rosacea, causes direct vasoconstriction. This
alpha-adrenergic receptor agonist is often used in conjunction with topical steroids to help
decrease the risk for PIH. Zinc oxide is a physical barrier sunscreen.
REFERENCES:
1. Wong ITY, Richer V. Prophylaxis of post-inflammatory hyperpigmentation from energy-
based device treatments: a review. J Cutan Med Surg. 2021;25(1):77-86. doi:
10.1177/1203475420957633
2. Farshidi D, Hovenic W, Zachary C. Erbium:yttrium aluminum garnet ablative laser
resurfacing for skin tightening. Dermatol Surg. 2014;40 Suppl 12:S152-6.

Question 4

A 24-year-old woman comes to the office because of a capillary malformation of the right cheek. Which of the following lasers is the most appropriate treatment in this patient?

A) Carbon dioxide laser (10,200 nm)
B) Er:YAG (2940 nm)
C) Nd:YAG (1064 nm)
D) Pulsed-dye (585 nm)
E) Q-switched ruby (694 nm)

Answer 4

The correct response is Option D.

The chromophore for the pulsed-dye laser at a wavelength of 585 nm is oxyhemoglobin. Thus, this laser is best suited to treat vascular lesions. Rhytides, acne scars, and dyschromias can also be managed by ablative resurfacing techniques, such as a carbon dioxide laser, which is absorbed by water. Er:YAG has a wavelength of 2940 nm and is absorbed by water. This laser causes less collateral thermal necrosis than a carbon dioxide laser. Acne scarring is best managed with infrared lasers at wavelengths of 1064 to 1540 nm. These include the Nd:YAG, diode, and erbium lasers. Tattoos are best managed with a Q-switched ruby laser at a wavelength of 694 nm, which is absorbed by melanin and carbon pigments.

Question 5

Which of the following treatment systems activates the topical formulation of 5-aminolevulinic acid?

(A) Erbium laser
(B) Phenol
(C) Pulsed-dye laser
(D) Radiofrequency
(E) Tretinoin

Answer 5

The correct response is Option C.

5-Aminolevulinic acid (ALA) is a topical medication that, when placed on the skin, penetrates the altered epithelial epidermis and is absorbed into the keratinocytes, whereby it is converted enzymatically into protoporphyrin IX. The application of light results in the release of cytotoxic radicals, which render this drug useful for the treatment of cutaneous lesions. Protoporphyrin IX has a maximum absorption at 410, 630, and 690 nm. Because of this, blue light systems (400B450 nm), pulsed-dye systems (585B595 nm), and photo rejuvenation systems (560B1200 nm) all may activate the drug. Recently, it has been used for the treatment of acne vulgaris as well as aging. It requires up to one hour of application time before initiation of therapy and may result in several days of swelling, erythema, and exfoliation. Patients also tend to be photosensitive for up to 48 hours after treatment. Radiofrequency and erbium (2940-nm) laser systems are not within the visible spectrum and will not activate protoporphyrin IX. Topical agents such as phenol and tretinoin will not activate this drug.

Question 6

A 42-year-old woman is scheduled to undergo facial resurfacing with a fractionated carbon dioxide laser. This procedure acts by targeting which of the following substances in skin?

A) Collagen
B) Elastin
C) Hyaluronic acid
D) Melanin
E) Water

Answer 6

The correct response is Option E.

The principle of selective photothermolysis as applied to skin resurfacing (ablation) is based upon water content. The epidermis is composed of 90% water and is vaporized at temperatures in excess of 212°F (100°C). The carbon dioxide laser has water as its chromophore. The carbon dioxide laser has a wavelength of 10,600 nm and has a water absorption coefficient of 800/cm.

The collagen, elastin, hyaluronic acid, and melanin content of skin may be affected by the temperature change from the laser energy, but water is the chromophore that is targeted by an ablative, fractionated carbon dioxide laser.

Question 7

Which of the following is the beneficial effect of pretreatment with tretinoin prior to facial chemical peel and laser resurfacing?
A) Decreased epidermal prolifereation
B) Decreased fibroblast deposition of glycosaminoglycans
C) Increased collagen IV deposition
D) Increased epidermal melanin
E) Increased transit rate of keratinocytes through the epidermis

Answer 7

’ correct answer is option E.

Use of retin-a as a pretreatment prior to laser treatment, allows for a more uniform skin layer for the laser to target. This can allow a more even distribution of the laser treatment throughout the treatment area.

Question 9

A 58-year-old woman plans to undergo Er:YAG laser resurfacing (2940 nm) to improve the appearance of perioral rhytides. The procedure targets which of the following?

A) Collagen
B) Elastin
C) Hemoglobin
D) Melanin
E) Water

Answer 9

The correct response is Option E.

Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.

Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12- to 16-fold greater than carbon dioxide laser. Targeting hemoglobin would not be appropriate since this will not lead to rejuvenation of perioral rhytides. The treatment of melanin is not the correct target since this would only lead to hypopigmentation or absorb the laser wavelength and lead to a possible burn. Collagen and elastin are essential elements of maintaining a youthful dermis; these dermal proteins are not the target of lasers, but rather induced by the trauma occurring from the laser itself.

Question 10

Which of the following light sources is noncoherent?

(A) Alexandrite
(B) Diode
(C) Intense pulsed
(D) Pulsed-dye
(E) YAG

Answer 10

The correct response is Option C.

Intense pulsed (broadband) light is a high-intensity light source that emits polychromatic energy. It supplies noncoherent light over a broad spectrum of wavelengths from 510 to 1200 nm. This broad spectrum allows variability regarding target selection and skin types. Intense pulsed-light systems are commonly used to treat hyperpigmentation, telangiectasis, rosacea, excessive or unwanted hair, rhytids, and vascular malformations. When used for photoaging, they have been shown to produce long-term positive results on the face, neck, and chest. They have also demonstrated improvement in telangiectasis and pigmentation. Adverse effects of intense pulsed light include crusting, erythema, and purpura.
Alexandrite, diode, pulsed-dye, and YAG laser systems emit monochromatic coherent light. Each device has a specific wavelength and chromophore.

Question 11

A 21-year-old woman with Fitzpatrick Type V skin presents for evaluation of acne scarring. Treatment with a fractional nonablative laser is planned. Which of the following lasers is most appropriate to treat acne in this patient?

A) Carbon dioxide (10,600 nm)
B) Erbium-doped fiber (1550 nm)
C) Erbium:YAG (2940 nm)
D) Erbium:YSGG (2790 nm)

Answer 11

The correct response is Option B.

Nonablative fractional lasers are commonly used for acne scar resurfacing in darker skin types. Nonablative lasers work by denaturation of dermal collagen with subsequent remodeling, without any vaporization or damage to the epidermis.

Erbium-doped fiber laser (1550 nm) is a nonablative laser while Erbium:YAG (2940 nm), carbon dioxide (10,600 nm), and Erbium:YSGG (2790 nm) are ablative lasers.

Question 12

A 23-year-old man who has the blue-green tattoo shown in the above photograph wishes to undergo tattoo removal. Which of the following is the most appropriate management?

(A) Carbon dioxide laser ablation
(B) Serial excision
(C) Excision and full-thickness skin grafting
(D) Multiple treatments with the Q-switched Nd:YAG laser
(E) Dermabrasion

Answer 12

The correct response is Option D.

The Q-switched Nd:YAG and alexandrite lasers are best used for removal of blue-green tattoo pigments. In contrast, the Nd:YAG laser works best for red, brown, and orange pigments, while the Q-switched ruby laser is used to remove tattoos with violet and purple pigments. Because professional tattoos often extend deep within the dermis, multiple treatments are required.

Because it causes minimal damage to adjacent tissues, the carbon dioxide laser is effective for ablation (skin resurfacing), cutting, and coagulation. Although serial excision can be used in the treatment of traumatic tattoos, scarring is a common sequela. Dermabrasion is recommended for small traumatic tattoos.

Question 13

A 17-year-old girl wishes to undergo removal of a butterfly-shaped tattoo that was professionally drawn in black ink on the skin overlying the right scapula. Which of the following lasers is most appropriate for removal?

(A) Carbon dioxide
(B) Copper vapor
(C) Erbium
(D) Nd:YAG
(E) Pulsed dye

Answer 13

The correct response is Option D.

The Nd:YAG laser is most appropriate for removal of this patient’s tattoo. This laser emits light at a wavelength of 1064 nm and is preferentially absorbed by dark pigments, such as blue and black. It penetrates the skin to a depth of 2 to 6 mm, which will result in disruption of the tattoo pigment. Multiple treatments are typically required.

Both carbon dioxide and erbium lasers are inappropriate for tattoo removal because they are chromophores of water. These lasers are typically used to resurface scarred or wrinkled areas of skin. The carbon dioxide laser emits light at a wavelength of 10,600 nm and can be used in a continuous mode to cut skin. The erbium laser emits light at a wavelength of 2940 nm.
The copper vapor and pulsed dye lasers produce light at wavelengths from 500 to 600 nm. Although their beams penetrate skin, their shortened wavelengths preclude deep penetration. These laser wavelengths are absorbed by red and brown chromophores.

Question 14

A 42-year-old woman comes to the office for consultation regarding improvement of the appearance of her facial skin. Resurfacing with a carbon dioxide laser is contraindicated in this patient if she has been treated recently with which of the following drugs?

(A) Acyclovir

(B) Glycolic acid

(C) Hydroquinone

(D) Isotretinoin

(E) Tretinoin

Answer 14

The correct response is Option D.

Unlike the other pretreatments, isotretinoin (Accutane) is contraindicated in any skin resurfacing procedures. Although its use for the treatment of acne is regulated, because of its significant risk for causing birth defects, it may also interfere with healing after resurfacing procedures. This complication may occur even if the medication has not been used for one year. For this reason, all patients should be asked about isotretinoin use before any resurfacing procedure is performed.

The remaining treatments are not a contraindication to facial skin resurfacing. Acyclovir is frequently administered before and after resurfacing procedures, particularly in patients with a history of herpes virus outbreaks. A glycolic acid peel may also be administered before resurfacing; however, little data show that it will prevent pigment changes or decrease inflammation after resurfacing. Hydroquinone may also be administered, but again, there is lack of good data that it provides significant improvement of pigment changes. Although similar to isotretinoin, tretinoin (Renova, Retin A) does not cause an increased risk of healing complications after laser resurfacing. It is frequently used as a pretreatment in such cases.

Question 15

A 37-year-old woman who underwent full-face resurfacing with a carbon dioxide laser seven days ago comes to the office because she has chills, malaise, and painful lesions of the face. Temperature is 38.7EC (101.7EF). Physical examination shows ulcerated, diffusely distributed lesions over the face. A four-day regimen of acyclovir 400 mg three times daily has not alleviated the patient €™s symptoms. Results of Tzanck smear and viral culture are pending. Which of the following therapies is the most appropriate next step in management?

(A) Intravenous acyclovir and ciprofloxacin

(B) Oral acyclovir at a higher dose

(C) Oral acyclovir at a more frequent dose

(D) Oral valacyclovir

(E) Oral valacyclovir and ciprofloxacin

Answer 15

The correct response is Option A.

The patient described has a presumptive diagnosis of cutaneous herpes simplex. Herpes simplex commonly is activated by laser resurfacing, spreads readily, and may scar. To avoid this complication, antiviral prophylaxis with one of the established drugs (acyclovir [Zovirax], famciclovir [Famvir], or valacyclovir [Valtrex]) should be started 24 to 48 hours before a laser resurfacing procedure and continued for 10 days until re €‘epithelialization is complete.

Herpes simplex is difficult to recognize on resurfaced skin. Moreover, primary or secondary bacterial infection cannot be overlooked. Therefore, antibiotic coverage is prudent, particularly until culture results are available.

When a patient experiences an outbreak of herpes simplex despite the use of antiviral prophylaxis, the physician should perform a Tzanck smear and send viral, fungal, and bacterial cultures. The anti €‘herpetic dosage should be increased to zoster levels as well (acyclovir 800 mg five times a day, valacyclovir 500 mg three times a day).

This patient presented with signs and symptoms of systemic herpetic infection, which may include disseminated cutaneous lesions, shortness of breath, high fever and chills, malaise, headache, and neurologic changes. When these are present, hospital-based treatment with intravenous antiviral and antibiotic therapy is warranted.

Question 16

Lasers are selected based on their ability to be selectively absorbed by target tissues known as chromophores. What are the three primary chromophores in the skin?
A) Hair follicles, sebaceous glands, water
B) Melanin, water, hemoglobin
C) Keratin, water, hair follicles
D) Hemoglobin, basal cells, sebaceous glands
E) Melanin, keratin, basal cells

Answer 16

Correct answer is option B.

The three main chromophores that lasers target are hemoglobin, melanin, and water.

Question 17

A 55-year-old woman with moderate sun damage to facial skin and facial wrinkles comes to the office for laser skin resurfacing. Which of the following is the most appropriate management regarding respiratory protection from the laser smoke plume?

A) High-efficiency smoke evacuator placed 20 to 25 cm away from the site of the laser plume
B) High-efficiency smoke evacuator placed within 1 to 2 cm of the smoke plume
C) Standard surgical mask alone
D) Standard wall suction
E) No specialized equipment or protection is necessary

Answer 17

The correct response is Option B.

Along with ocular hazards and fire hazards, laser smoke plume is a significant occupational hazard, which is often ignored when lasers are used. There are numerous substances, some carcinogenic and mutagenic, released during laser pyrolysis of tissue. Viable skin bacteria, including coagulase-negative Staphylococcus, Corynebacterium, and Neisseria, have been recovered from the laser plume following laser skin resurfacing. In addition, intact viral DNA, particularly of human papillomavirus, has been isolated from carbon dioxide laser plume. Most surgical masks only filter particles that are 5 microns in diameter or larger; however, 77% of particles in the laser plume are 1 micron or smaller. Therefore, well-fitted high-filtration or laser masks should be used instead of standard surgical masks. A high-efficiency smoke evacuator should also be used, but it needs to be within 1 to 2 cm of the laser smoke plume source. The effectiveness of the smoke evacuator is decreased from 99 to 50% as the distance from the laser-treated site is increased from 1 to 2 cm, so 20 to 25 cm away is ineffective.

Question 18

A 46-year-old woman comes to the office for evaluation of persistent erythema 2 weeks after she underwent full-face carbon dioxide laser resurfacing. Which of the following topical treatments is most appropriate to decrease this patient’s postoperative erythema?

A) Amoxicillin
B) Ascorbic acid
C) Hydroquinone
D) Prednisone
E) Valacyclovir

Answer 18

The correct response is Option B.

Erythema following laser resurfacing is an anticipated consequence of therapy. Posttreatment erythema is more severe and of longer duration with carbon dioxide laser resurfacing when compared to the fractionated carbon dioxide or Er:YAG laser. Postoperative topical application of ascorbic acid has been shown to decrease the duration as well as the severity of erythema. Topical therapy with ascorbic acid should be applied following reepithelialization. Antibiotics or antivirals have not been shown to decrease erythema. Hydroquinone is a skin bleaching agent that does not treat erythema. Topical corticosteroids postoperatively may delay reepithelialization and have not been associated with a decrease in erythema.

Question 19

An Er:YAG laser targets which of the following chromophores?

(A) Blue dye

(B) Collagen

(C) Hemoglobin

(D) Melanin

(E) Water

Answer 19

The correct response is Option E.

Lasers generate heat in the target tissue that dissipates by conduction. The amount of heat generated is a function of the wavelength of the laser and the duration of exposure. Selective tissue injury is caused by the choice of a wavelength of energy that is specific for a particular target chromophore within the skin.

The Er:YAG laser is an ablative laser with a wavelength of 2940 nm and a target chromophore of water. There is less thermal diffusion to the surrounding tissues with an Er:YAG laser than with a CO2 laser, although both have the same target chromophore.

Fractional photothermolysis uses a blue dye template, which also serves as the target chromophore, and divides the skin into microscopic thermal zones. The Nd:YAG laser affects blood vessels, red blood cells, collagen, and melanin. Intense pulsed light targets water, hemoglobin, and superficial or deeper pigment, depending on the wavelength.

Question 20

A 28-year-old woman undergoes laser removal of a multicolored tattoo on the upper arm. The tattoo was professionally applied. Which of the following laser wavelengths is most appropriate to remove the yellow portions of this tattoo?
(A) 532 nm
(B) 698 nm
(C) 755 nm
(D) 1064 nm
(E) 1320 nm

Answer 20

The correct response is Option A.

Choice of lasers for the treatment of tattoos is guided by the absorption spectrum of the ink colors present within the tattoo. Orange and yellow tattoo inks are targeted specifically by lasers in the low (500-nm) range, making the 532-nm Q-switched Nd:YAG laser or the 510-nm pulsed-dye laser optimal for treatment.

The Q-switched alexandrite (755-nm) and Q-switched ruby (694-nm) lasers can be used for black, blue, and green pigments. The Q-switched Nd:YAG (1064-nm) laser is optimal for black pigment.

Nd:YAG, long-pulsed 1320-nm laser treatment was the first system developed solely for nonablative skin remodeling.

Question 21

An 18-year-old woman with Fitzpatrick type IV skin presents for carbon dioxide laser treatment for hypertrophic scarring 1 year after sustaining facial burns. Two weeks after the first session, hypopigmentation is noted in the laser-treated areas. Which of the following adjustments to the laser setting is most likely to prevent further hypopigmentation from occurring after the next session?

A) Decreasing the dwell time
B) Decreasing the spot size
C) Increasing the dwell time
D) Increasing the energy
E) Increasing the spot size

Answer 21

The correct response is Option A.

Patients classified as higher Fitzpatrick types have a higher risk for hypopigmentation after carbon dioxide laser therapy. For example, punctate hypopigmentation has been found in up to 35% of facial burn patients presenting 2 months after being treated with fractionated carbon dioxide laser therapy. To decrease the risk for further hypopigmentation, the dwell time needs to be decreased. Increasing the dwell time prolongs the time of exposure, increasing the risk for hypopigmentation. Increasing or decreasing the spot size only increases or decreases the surface area treated. Increasing the energy would also increase the risk for hypopigmentation.

Question 22

A 30-year-old woman of Nordic heritage is interested in laser hair removal of “peach fuzz” on the upper lip. She has Fitzpatrick Type I skin and is very fair, with light blonde hair and blue eyes. Which of the following is the most appropriate technique for hair removal for this patient?

A) Alexandrite laser (755 nm)
B) Electrolysis
C) Intense pulsed-light
D) Long-pulse ruby laser (694 nm)
E) Nd:YAG laser (1064 nm)

Answer 22

The correct response is Option B.

Laser hair removal targets the melanin in the hair follicle. It is not useful in fair-haired patients who have low levels of melanin in their hair follicles.

Although all the devices listed here have been employed for hair reduction, only electrolysis would be likely to work in this patient.

Question 23

A 23-year-old woman has carbonaceous material embedded in the skin after sustaining injuries in a combustion accident at work. A photograph is shown above. Which of the following is the most appropriate management?

(A) Carbon dioxide laser therapy
(B) Nd:YAG laser therapy
(C) Deep dermabrasion
(D) Wide local excision and coverage with a thin split-thickness skin graft

Answer 23

The correct response is Option B.

In patients who have certain types of foreign material embedded in the skin, especially road asphalt, carbonaceous material, or ink from amateur tattoos, the most appropriate method of removal is multiple treatments with the Nd:YAG laser.

In the past, traumatic tattoos were removed with mechanical abrasive techniques, including dermabrasion, salabrasion, and the rubbing of table salt into the skin, each of which produced satisfactory results in superficial tattoos. However, better results have recently been demonstrated with laser therapy, which involves the removal of successive layers of skin to expose the intradermal pigment, which is subsequently vaporized.

The surgeon should take great care while administering Nd:YAG laser treatments in any patient who has sustained injuries resulting from a gunpowder or fireworks accident, as the unburned, embedded gunpowder can actually combust during treatment, leading to unacceptable scarring.

Although laser therapy is the treatment of choice for traumatic tattoos, the carbon dioxide laser is not recommended because it does not effectively remove embedded carbonaceous material. In addition, this laser has no selective absorption; as a result, epidermal structures are injured more easily and scarring is increased.

Deep dermabrasion and wide local excision combined with thin split-thickness skin grafting are excessively invasive procedures that will yield poor cometic results.

Question 24

A 40-year-old woman with Fitzpatrick type II skin is scheduled to undergo carbon dioxide laser resurfacing for facial rhytides. Current use of which of the following medications is a contraindication for use of carbon dioxide laser resurfacing in this patient?
(A) Hydroquinone
(B) Isotretinoin
(C) Nicotine patch
(D) Oral contraceptive
(E) Valacyclovir

Answer 24

The correct response is Option B.

Laser resurfacing of the skin (as well as other resurfacing modalities such as dermabrasion and chemical peels) is contraindicated in patients who have used isotretinoin (Accutane, an oral retinoid) within 18 months. Isotretinoin suppresses skin appendageal activity and, therefore, prevents normal reepithelialization after resurfacing. If the wounded skin is not reepithelialized within 10 days, scarring may result. Many clinicians wait 24 months after the last oral retinoid dose was administered before performing skin resurfacing. Note that topical retinoids such as isotretinoin (Retin-A) do not have this effect on skin appendages and their use is not a contraindication to skin resurfacing.

Hydroquinone is a tyrosinase inhibitor and results in lightening (bleaching) of the skin. It is frequently used before and after skin resurfacing to prevent hyperpigmentation.

Valacyclovir, an oral antiviral, is indicated in patients with a history of oral herpes simplex outbreaks. It should be started before the procedure and continued until reepithelialization occurs.

Oral contraceptives and nicotine patches have not been shown to cause complications after skin resurfacing.

Question 25

A patient with Fitz Type III undergoes CO2 laser skin resurfacing for facial rhytides and acne scars. Prior to the procedure the patient was compliant with their pre-operative regimen. What is the patient at most risk for after the procedure?
A) Treatment failure
B) Postinflammatory hyperpigmentation
C) Eczematous dermatitis
D) Infection
E) Scarring

Answer 25

Correct answer is option B.

Higher Fitz level patients are more prone for post inflammatory hyperpigmentation (PIH). Preventative measures such as hydroquinone can decrease the risk of PIH.

Question 26

A 45-year-old woman comes to the office because of a rash and a burning sensation on her face 1 week after undergoing carbon dioxide cutaneous laser resurfacing. Physical examination shows erythematous pustules on the right side of the face in the V3 distribution. Which of the following agents is the most appropriate treatment?

A ) Oral acyclovir

B ) Oral cephalexin

C ) Oral prednisone

D ) Topical bacitracin

E ) Topical petrolatum

Answer 26

The correct response is Option A.

The patient €™s symptoms are consistent with a viral infection. Viral, bacterial, and fungal infections can develop after cutaneous laser resurfacing, usually at the time of the first postoperative week during the reepithelialization process. The most frequent infectious complication associated with resurfacing is a reactivation of the herpes simplex virus (HSV). It is suspected that direct laser trauma to the skin leads to latent viral activation and shedding. Herpetic outbreaks are experienced by roughly 2 to 7% of all laser-treated patients despite antiviral prophylaxis. In addition, due to the high incidence of latent HSV infection, any patient (regardless of prior HSV history) planning to undergo full-face or perioral resurfacing should be given oral antiviral prophylaxis in an effort to reduce viral reactivation, which could subsequently lead to scarring. Early postlaser detection of HSV is often difficult because there is no intact epithelium, and, rather than the characteristic grouped vesicles or pustules, infection is manifested by small, superficial erosions. Symptoms of HSV reactivation include tingling, burning, or discharge from isolated foci within the treated areas. Extensive eruptions can result in disseminated infection and atrophic scarring, and therefore, must be recognized early and treated aggressively. Oral antiviral agents, such as acyclovir, famciclovir, or valacyclovir, are routinely administered 1 to 2 days before the laser resurfacing procedure and are continued for another 7 to 10 days until reepithelialization is complete. If a herpetic outbreak occurs despite prophylaxis, patients should either be switched to a different antiviral agent or have their dosage increased to maximal herpes zoster doses (acyclovir 800 mg 5 times daily or famciclovir or valacyclovir 500 mg 3 times daily).

Cephalexin would be more appropriate for bacterial skin infections. Bacitracin does not have antiviral coverage. Topical petrolatum is a bland emollient and would not treat the HSV outbreak. Oral corticosteroids do not have any role in the treatment of viral infections.

Question 27

A 54-year-old man with Fitzpatrick type II skin is scheduled to undergo photoaging treatment with a carbon dioxide fractional laser. Which of the following measures is most likely to decrease this patient’s risk of hypertrophic scarring?

A) Decreasing fluences
B) Heat stacking
C) Increasing surface area coverage
D) Treating the neck skin
E) Using multiple laser passes

Answer 27

The correct response is Option A.

Fractional laser resurfacing of photo-damaged or acne-scarred skin has supplanted traditional carbon dioxide ablative laser devices while diminishing the incidence of adverse effects and effecting a more rapid recovery. However, hypertrophic scarring (HTS) is a noteworthy complication that requires the utilization of preventive measures to minimize its occurrence. Conservative treatment of the neck is foremost among these measures. Use of lower fluences (energy density, defined as Joules/cm2) treating reduced surface areas, abstinence from heat stacking, and avoiding multiple passes by a carbon dioxide laser all contribute to less incidence of HTS. Patient selection, preoperative education, and preparation for treatment of this complication are appropriate adjunctive measures as well.

Question 28

A 59-year-old woman comes to the office because she is unhappy with the long-term results of carbon dioxide laser resurfacing performed three years earlier to treat rhytides on the upper lip. Which of the following is the most likely complication that is causing her dissatisfaction?

A ) Hyperpigmentation

B ) Hypertrophic scarring

C ) Hypopigmentation

D ) Persistent erythema

E ) Telangiectasia

Answer 28

The correct response is Option C.

Carbon dioxide laser resurfacing is a highly effective treatment of rhytides of the upper lip that will last for a long time (more than six years) with low rates of recurrence. The success of carbon dioxide laser skin resurfacing is generally attributed to long-term neocollagenesis and neoelastogenesis. The main drawback is a high rate of hypopigmentation, which is very distressing to patients. Although persistent erythema and hyperpigmentation can be troublesome in the first year after treatment, neither is typically seen as long-term sequelae of the procedure. Hypertrophic scarring is a possible complication of treatment; however, it is not reported as a common long-term complication of the procedure in several large series of studies.

Question 29

A 50-year-old woman comes to the office because she developed a vesicular rash five days after undergoing full face carbon dioxide laser resurfacing to treat sun-damaged skin and acne scars. Which of the following is the most appropriate initial step in management?

A ) Administration of an antibiotic

B ) Administration of an antimicrobial scrub

C ) Administration of an antiviral agent

D ) Administration of a corticosteroid

E ) Observation

Answer 29

The correct response is Option C.

The patient described has most likely suffered from an outbreak of herpes simplex virus (HSV), which may occur with any resurfacing procedure, including laser, peels, and dermabrasion. Oral antiherpetic medication, such as acyclovir, valacyclovir, or famciclovir, should be prescribed prophylactically for all patients receiving resurfacing treatment, to start two days prior to the treatment and continuing for 7 to 10 days while the patient heals. HSV infection has a three- to five-day incubation period from the time of the procedure to the onset of clinical infection. If outbreak occurs €”and this rarely happens while taking antiviral prophylaxis €”treatment dosing of antiviral medication must be administered.

Question 30

A 32-year-old woman comes to the office for consultation regarding removal of a black and red tattoo from the left breast. The most effective intervention for removal of this patient’s tattoo is treatment with which of the following types of lasers?

(A) Carbon dioxide
(B) Pulsed-dye
(C) Q-switched alexandrite
(D) Q-switched Nd:YAG
(E) Q-switched ruby

Answer 30

The correct response is Option D.

The current standard of care for removing most unwanted tattoos is use of specific lasers to target the wavelength of the color pigments. No one laser can selectively target each pigment type in the spectrum of colors used by professional tattoo artists.

A Q-switched laser delivers short pulses, which reduces damage to surrounding normal skin. A frequency-doubled Q-switched Nd:YAG laser has a crystal that doubles the frequency of the Nd:YAG laser from 1064 nm to 532 nm. In the 532-nm (green) wavelength, the laser removes red pigments effectively. When switched to the full 1064-nm (red) wavelength, it effectively removes black pigments. The mechanism of action is believed to be selective fragmentation of the targeted pigment followed by phagocytosis and lymphatic clearing.

A carbon dioxide laser removes tattoos by targeting water in the skin. Therefore, it nonselectively destroys tissue, including pigment-bearing cells. Because it poses a high risk of hypopigmentation and hypertrophic scarring, it is not the laser of choice for removing professional tattoos.

A pulsed-dye laser has a wavelength of 510 nm; it can remove red pigments but is a poor choice for black pigments. A Q-switched alexandrite laser, with a wavelength of 755 nm, is excellent at removing black and green pigments but not reds. A Q-switched ruby laser, which has a wavelength of 694 nm, also is excellent for removing black pigments but is poor at targeting reds. In addition, it may produce more damage to surrounding tissue than the alexandrite laser.

Question 31

Which of the following laser wavelengths is ideal for treating the lesion shown above?

(A) 532 nm
(B) 585 nm
(C) 788 nm
(D) 810 nm
(E) 2940 nm

Answer 31

The correct response is Option B.

The patient depicted in the photograph has a port-wine stain in the VBIII distribution of the trigeminal (V) nerve. These lesions may occur anywhere on the body but are most commonly seen on the face. They occur unilaterally in 85% of patients and involve more than one dermatome in almost 70% of patients. These lesions are more commonly seen in women than in men (3:1) and may be hereditary (25%). The natural progression of these lesions with age includes darkening of the lesion due to the presence of deoxyhemoglobin, with thickening of the dermis and a cobblestoning appearance. It should be noted that as the lesions get darker, they are more difficult to treat. Because of its depth, penetration, and specificity for vascular targets, the 585-nm laser is the best treatment choice for these lesions. Treatment with the pulsed-dye laser typically results in less epidermal injury and risks for scarring. It should be used with caution in patients with pigment.

The 532-nm laser (KTP) is useful for superficial vascular telangiectasis. Both the 788- and 810-nm lasers are useful for pigmentation as well as hair removal. Finally, the 2940-nm laser (erbium) is a resurfacing device and is not specific for vascular targets.

Question 32

Which of the following characteristics of the carbon dioxide laser best explains the greater level of peripheral dermal injury that occurs with this laser than with the Er:YAG laser?

(A) Decreased thermal diffusion
(B) Less collagen contraction
(C) Limited coagulative necrosis
(D) Lower affinity for water
(E) Shorter pulse duration

Answer 32

The correct response is Option D.

Although the carbon dioxide and Er:YAG lasers are both absorbed by water, the Er:YAG laser has an affinity for water that is ten times greater than the carbon dioxide laser. It has an efficient rate of absorption and a short duration of exposure; each pass of the laser results in only minimal tissue necrosis. In addition, the pulse duration of the Er:YAG laser is shorter. Because it produces limited coagulative necrosis, the effect of erbium is photomechanical, rather than photothermal, and the amount of collagen contraction is much less than that produced by the carbon dioxide laser. Although the Er:YAG laser is well suited for fine ablation of the epidermis, it does not stimulate continued collagen remodeling.

In contrast, the carbon dioxide laser produces a greater thermal effect on surrounding tissue and subsequent collateral injury, resulting in continued remodeling of collagen and a greater overall cosmetic improvement.

Question 33

An 8-month-old boy is brought to the office for evaluation of a capillary malformation involving the right side of the chest and right cheek. Physical examination shows red cutaneous discolorations in a dermatomal distribution. Which of the following lasers is most appropriate to treat this condition?

A ) Carbon dioxide laser (10,200 nm)
B ) Nd:YAG (1064 nm)
C ) Pulsed-dye (585 nm)
D ) Q-switched alexandrite (755 nm)
E ) Q-switched ruby (694 nm)

Answer 33

The correct response is Option C.

Pulsed-dye laser with epidermal cooling remains the standard means of treating port-wine stains in the pediatric population. Intense pulsed-light devices have also been used with some effectiveness. The principles of selective thermolysis play a critical role in optimizing the treatment of port-wine stains. Oxyhemoglobin serves as the target chromophore, exhibiting three absorption peaks (418, 542, and 577 nm). Currently, the 585-nm and 595-nm pulsed-dye lasers appear to be the most popular choices and are most effective because of their proximity to an absorption peak and even deeper penetration. Depth of penetration is further enhanced by using a larger spot size (10 mm).

Neodymium: yttrium-aluminum-garnet (Nd:YAG) laser treatment has surfaced as an effective treatment for superficial venous malformations. The Q-switched alexandrite laser is effective in tattoo removal of black, blue, and green inks. The Q-switched ruby laser is effective in removing tattoos with minimal scarring and removes black, blue-black, and green ink.

Question 34

A healthy 48-year-old woman comes to the office for consultation regarding laser resurfacing of fine facial wrinkles in the perioral region. Her skin color is light brown and she states that she rarely gets sunburned (Fitzpatrick Type IV). Examination shows rhytides in the perioral region, on the forehead, and in the lateral canthal region. Compared with a patient who has a lighter skin color (Fitzpatrick Type I-III), which of the following is this patient at increased risk for after laser resurfacing in the perioral region?

A) Freckles
B) Herpetic lesions
C) Hypertrophic scars
D) Post-treatment hyperemia
E) Postinflammatory hyperpigmentation

Answer 34

The correct response is Option E.

Understanding the potential complications after facial resurfacing is important to know, especially those complications that occur in patients with darker skin. Traditionally, the Fitzpatrick Scale is used to assess skin tone and risk for both the development of skin cancer and also response to post-treatment pigmentation issues. Herpetic lesions can develop in individuals with any skin color after laser treatment. While hyperemia can develop in any patient after laser resurfacing, post-inflammatory hyperpigmentation is of greatest concern in those with darker skin color, especially in an individual like the one described, who has a Fitzpatrick Type IV skin type. While there are different ways to mitigate the issue of pigmentation both before and after treatment, it is a risk factor that should be discussed with patients undergoing skin resurfacing, especially in darker skin individuals. Laser therapy has been used to treat hypertrophic scars and freckles.

Question 35

After laser removal of an elaborate multi-color tattoo, a patient has residual green ink remaining. Which of the following is the most appropriate treatment for this residual pigment?

A) Carbon dioxide laser
B) Intense pulsed light
C) Long pulse Nd:YAG (1064-nm) laser
D) Q-switched alexandrite (755-nm) laser
E) 70% Trichloroacetic acid peel

Answer 35

The correct response is Option D.

Green tattoo ink responds effectively to treatment with a 755-nm Q-switched alexandrite laser. As of 2013, a picosecond-domain alexandrite laser became commercially available, giving 75% clearance of green pigment in just one to two treatments in fair-skinned patients. Alternatively, ruby lasers, with a 694-nm wavelength, can be used.

The 1064-nm wavelength is very effective for black and other dark colors when a Q-switched or picosecond machine is used. Typically, this wavelength is less effective for green, with this color commonly being left behind after completion of a 1064-nm treatment series.

The long-pulse Nd:YAG is used for hair removal and varicose veins. It does not have the short pulse width required for effective tattoo removal. Similarly, intense pulsed light (IPL), even when filtered to the correct wavelength, doesn’t give the short pulse width required for tattoo removal. Long-pulse laser or IPL pulses in the millisecond domain usually result in incomplete tattoo clearance, thermal damage to surrounding tissues, and scarring.

Trichloroacetic acid (TCA) peels are not pigment-specific. They have become popular with the do-it-yourself patient population, with unregulated sales over the Internet, leading to reports of hypertrophic scarring and chemical burns requiring formal excision and skin grafting. A TCA peel is not recommended as a tattoo treatment, even in the more commonly used concentrations of 30 to 40%, which are used for facial resurfacing.

Carbon dioxide laser is not effective at targeting tattoo pigment.

Question 36

A 58-year-old woman with a history of rosacea is scheduled to undergo Er:YAG laser resurfacing to improve the appearance of perioral rhytids. When compared with a carbon dioxide laser, for which of the following does the Er:YAG laser have a greater affinity?

A) Hair follicle
B) Hemoglobin
C) Melanin
D) Papillary dermis
E) Water

Answer 36

The correct response is Option E.

Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.

Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. Tissues that are heated to 60° to 70°C (140°F to 158°F) coagulate; above 100°C (212°F), vaporization occurs. The carbon dioxide laser has a wavelength of 10,600 nm with a target chromophore of water. In the mid 1990s, the ability to deliver increasing power over shorter amounts of time allowed temperatures to be reached that would allow ablation of the epidermis. However, even with ablation there was a zone of coagulation surrounding the ablation that ranged between 70 and 120 ?m. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12 - to 16-fold greater than carbon dioxide laser. Because of this unique feature, the ablation threshold of Er:YAG is only 1 J/cm2 compared with the carbon dioxide laser’s ablation threshold of 5 J/cm2. The clinical relevance is that a much higher percentage of targeted tissue is ablated rather than heated, so that the resultant surrounding coagulation zone is only 5 to 20 ?m of tissue.

It is a common mischaracterization of full-field resurfacing options to state that “erbium is more superficial than carbon dioxide.” This is only true for a single pulse and equivalent energies, as the erbium wavelength is rapidly absorbed in water at a rate 11 to 16 times higher than carbon dioxide. However, such a statement is contrary to the fact, as erbium allows ablation of the dermis and the epidermis, unlike carbon dioxide, which can only ablate epidermis. Erbium can easily ablate the dermis on successive pulses until the skin, muscle, and even bone can be totally obliterated. Carbon dioxide can only affect deep tissue by stacking pulses and creating “bulk heat” that melts the tissue rather than ablating, and is both imprecise and dangerous.

Erbium provides a controlled depth of ablation with a minimal underlying thermal zone of coagulation. This decrease in thermal injury leads to a faster recovery following erbium laser ablation compared with carbon dioxide laser. The smaller coagulative zone results in a lower rate of hypopigmentation and allows for a more controlled depth with each pass. Carbon dioxide lasers can have variable depth of penetration, especially after the first pass when the dermis is exposed, and the residual thermal injury creates a “char,” which becomes thicker with each pass, making penetration increasingly difficult.

Question 37

Which of the following is most effective in decreasing the risk of fire when using a carbon dioxide laser for facial resurfacing?

A) Clamp the laser cord to surgical drapes
B) Intubate laser patients to prevent oxygen accumulation on the field
C) Provide supplemental oxygen with a nasopharyngeal cannula
D) Use conscious sedation, nerve blocks, and no supplemental oxygen
E) Use foot pedals only for activating the laser

Answer 37

The correct response is Option D.

Carbon dioxide laser treatments can cause operating room fires. Several papers have shown that a nasopharyngeal oxygen delivery can decrease oxygen levels in the operative field when it is required, but the best way to decrease the level of oxygen on the field is not to use it. Foot pedals can be accidentally activated and should be avoided. Clamping the laser cord can damage the fibers and ignite the laser fiber sheath. Laser skin surfacing can be accomplished without intubation.

Question 38

A 22-year-old man comes for consultation regarding laser removal of a tattoo located on the upper lateral arm. He said his friend tattooed him 6 years ago using a sewing needle and black pen ink. Physical examination shows Fitzpatrick Type IV skin. Which of the following laser treatments is most likely to decrease the risk of scarring in this patient?

A ) Argon-pumped tunable dye
B ) Carbon dioxide
C ) Er:YAG
D ) Flash lamp-pumped pulsed-dye
E ) Q-switched ruby

Answer 38

The correct response is Option E.

Most amateur tattoos are characterized by pigment deposited at variable, sometimes excessive depths compared with those produced by a professional apparatus. This may compromise the ability to erase the tattoo in a single session or at all without resorting to more traditional measures, such as direct excision. The chromophore of the carbon dioxide laser is water; therefore, it will indiscriminately destroy unaffected skin, as well as the skin containing tattoo pigment. Fitzpatrick Type IV skin is that which, while resistant to sunburn, is more likely to demonstrate a genetic predisposition to hypertrophic scarring. Ablative laser treatment has been shown to adversely affect the risk of hypertrophism. Current safety guidelines require that all individuals present during laser therapy don appropriate eyewear, selected according to the laser wavelength. Q-switched lasers, including ruby, Nd:YAG, and alexandrite types, are based on the principle of selective photothermolysis. They are suited for removal of black tattoo pigments as well as a variety of colors while minimizing the risk of scar.

Question 39

A 54-year-old woman comes to the office because of severe facial rhytides and photodamage. Examination shows Fitzpatrick skin type III. Ablative laser resurfacing is planned. Which of the following is the most likely complication of laser resurfacing in this patient?

A) Acneiform eruption
B) Bacterial infection
C) Erythema
D) Hyperpigmentation
E) Scarring

Answer 39

The correct response is Option D.

Hyperpigmentation is the most common adverse effect of laser resurfacing. It occurs in 36% of patients and is most common in people with Fitzpatrick skin Types III to VI. Treatment consists of hydroquinone and tretinoin. Sun exposure should be avoided. Rates of hyperpigmentation can be reduced in those pretreated with retinoic acid and bleaching agents. While hyperpigmentation can be permanent, with proper treatment it usually resolves within a few months.

Acne can occur post-laser treatment. It is especially common in patients with a prior history and should be treated with standard acne therapies. Infection risk from bacteria is minimized with prophylactic antibiotics and good topical care. Viral herpes simplex outbreaks can occur in those with and without a history. Antiviral prophylaxis is now used in all patients undergoing laser resurfacing. Yeast infections are also a possible infectious complication. These respond well to systemic antifungals. Scarring can occur with improper technique that causes excessive thermal damage (i.e., too many passes and excessive energy fluencies). Areas that develop scarring can be treated with topical and intralesional corticosteroids, silicone sheeting, and pulsed-dye laser. Erythema is not considered a complication and is a normal part of the healing process. It can last 1 to 4 months depending on the type of laser used.

Question 40

A 35-year-old woman comes to the office for removal of the tattoo shown in the photograph. The tattoo was professionally applied. The patient undergoes five treatments with a Q €‘switched Nd:YAG (1064 nm) laser. After completion of laser therapy, areas of red pigment remain. Additional treatment with which of the following lasers is the most appropriate next step in management?

(A) Erbium: YAG (2940 nm)

(B) Q €‘switched alexandrite (755 nm)

(C) Q-switched Nd:YAG (532 nm)

(D) Q €‘switched ruby (694 nm)

(E) Ultrapulsed CO2 (10,600 nm)

Answer 40

The correct response is Option C.

An estimated seven to 20 million people in the United States have at least one tattoo, and approximately 17% have considered tattoo removal. Compared with amateur tattoos, professional tattoos often contain various densely packed colored pigments at a uniform depth. Quality €‘switched (Q €‘switched) lasers enable the deposit of energy very quickly, thus rupturing cells containing pigment and triggering phagocytosis and packaging of tattoo fragments for lymphatic drainage. Because different pigments respond to different wavelengths, it is rare that one laser system can be used alone to remove all combinations of inks.

The Q-switched Nd:YAG 1064 nm has the deepest penetration and carries the least risk of hypopigmentation but is least effective in removing brightly colored tattoos. In contrast, the Nd:YAG 532 nm is effective for red, orange, and occasionally yellow ink. Because this wavelength is also absorbed by hemoglobin, purpura often occurs after treatment and can last for seven to 10 days.

CO2 and erbium lasers are preferred for laser resurfacing and are less effective for tattoo removal.

The Q €‘switched alexandrite and ruby lasers are effective for the treatment of black, blue, and green pigment; however, because their wavelengths are well absorbed by melanin, transient hypopigmentation and even permanent depigmentation can be a problem, particularly in patients with Fitzpatrick type V or VI skin types.

Question 41

Which of the following findings is more likely in patients who undergo resurfacing with the erbium:YAG laser than in patients treated with the carbon dioxide laser?

(A) Erythema
(B) Hypopigmentation
(C) Scarring
(D) Skin tightening
(E) Transudate wound

Answer 41

The correct response is Option E.

The erbium:YAG (Er:YAG) laser is now the treatment of choice for ablative resurfacing of the skin. This laser emits light at a wavelength of 2940 nanometers (nm) and is absorbed by water within the epidermis a minimum of 10 times more efficiently than the carbon dioxide laser. The decreased dermal heating that occurs during treatment with the Er:YAG laser results in minimal long-term contraction of the dermis, but produces a transudative wound once the epidermis has been eliminated. The transudation becomes more profuse as the surgeon ablates deeper into the dermis.

Because the mechanism of action of the Er:YAG laser is photomechanical rather than photothermal, coagulation necrosis is limited and hyperemia is decreased. As a result, permanent hypopigmentation occurs in less than 5% of patients undergoing treatment with the Er:YAG laser. In contrast, permanent hypopigmentation has been reported in as many as 40% of patients undergoing carbon dioxide laser therapy.

Scarring may occur with any type of laser and is related to the amount of heat generated from the laser, also known as its pulse.

Likewise, skin tightening occurs with both the Er:YAG and the carbon dioxide laser.

Question 42

In a 5-year-old child who has a large capillary vascular malformation on the upper eyelid, which of the following lasers is most appropriate for removal?

(A) Alexandrite
(B) Carbon dioxide
(C) Nd:YAG
(D) Pulsed dye
(E) Q-switched ruby

Answer 42

The correct response is Option D.

Removal of the capillary vascular malformation, or port-wine stain, is best accomplished with use of a flashlamp-pumped pulsed dye laser. This laser delivers short pulses (450 msec) of 585 nm of yellow light that are selectively absorbed by hemoglobin and oxyhemoglobin chromophores. Multiple treatments will result in ablation of the malformation.

Vascular lasers and other pigment-specific lasers function according to the principle of selective photothermolysis, which describes the resultant localized tissue damage. Target tissue damage occurs when light of a particular wavelength is delivered to and absorbed by the target, but not the surrounding tissue, during a pulse duration less than or equal to the thermal relaxation time of the target.

Carbon dioxide lasers act to vaporize water within the tissues. The mechanism of these lasers is similar to chemical peeling and dermabrasion and is inappropriate for port-wine stains.

At 1064 nm, the Nd:YAG laser is outside of the absorbable spectrum for hemoglobin; therefore, this laser is not recommended for the treatment of port-wine stains.

Question 43

An 18-year-old woman has a large arteriovenous malformation on the face that has ulcerated and bled vigorously several times. Which of the following is the most appropriate treatment option?

(A) Intralesional administration of interferon
(B) Distal embolization under superselective angiographic control
(C) Ligation of the feeding vessels
(D) Intralesional excision to minimize tissue loss
(E) Aggressive resection with immediate flap reconstruction

Answer 43

The correct response is Option E.

This 18-year-old woman has a large arteriovenous malformation (AVM) on the face characterized by ulceration and bleeding. The most appropriate management is aggressive resection to eliminate the lesion immediately. In addition, because aggressive resection of an AVM typically exposes vital structures and leaves a cosmetically disfiguring defect, immediate reconstruction with a flap is indicated. Arteriography, Doppler ultrasonography, and/or MRI should be obtained preoperatively to delineate the extent of the lesion.

Distal embolization of the lesion can be performed under angiographic control before excision to limit blood loss but is not an effective treatment in itself.

Ligation of the feeding vessels without subsequent resection will further worsen the AVM because it will result in the development of new collateral vessels. Intralesional excision is associated with a high risk for recurrence.

Intralesional interferon has not been shown to provide benefit in the treatment of arteriovenous malformations.

Question 44

A 27-year-old woman presents with a multicolored decorative tattoo on her leg. She is interested in laser tattoo removal. On physical examination, over 80% of her tattoo has red and orange colors. Which of the following laser treatments would be most effective on the orange and red areas?

A) 755-nm Q-switched alexandrite
B) 532-nm Q-switched Nd:YAG
C) 1064-nm Q-switched Nd:YAG
D) 694-nm Q-switched ruby

Answer 44

The correct response is Option B.

Successful tattoo removal can be performed using different types of laser wavelengths. The 532-nm Q-switched Nd:YAG would be used for targeting red, yellow, and orange color tattoos. Black pigments can be effectively removed with Q-switched Ruby 694-nm, 755-nm Alexandrite, or 1064-nm Nd:YAG lasers. Purple ink responds best to the Q-switched 694-nm ruby laser and green ink best removed with the Q-switched 755-nm Alexandrite laser. The Q-switched Ruby 694 nm laser creates a red light that is highly absorbed by green, blue, and dark tattoo pigments.

Common Laser Types and Wavelengths:

Nd:YAG Laser:
-1064 nm: Ideal for removing black and dark blue inks. This wavelength is highly absorbed by dark pigments.

-532 nm: Effective for red, orange, yellow, and other warm-toned colors.

Alexandrite Laser:
-755 nm: Best for green and light blue inks. This wavelength is particularly effective for stubborn colors that are difficult to remove.

Ruby Laser:
-694 nm: Also used for green and blue inks, especially lighter shades.

Picosecond Lasers:
These lasers can operate at multiple wavelengths (e.g., 532 nm, 755 nm, 1064 nm) and deliver ultra-short pulses, making them effective for a wide range of colors and faster ink particle breakdown.

Key Points:
Multiple Wavelengths: Effective tattoo removal often requires using multiple wavelengths to target different colors within the same tattoo.

Light Absorption: The principle of light absorption is crucial; the laser wavelength must be well-absorbed by the tattoo ink to break it down effectively.

Treatment Sessions: Colored tattoos typically require several sessions for complete removal, as different colors respond differently to laser treatment.

Question 45

A 38-year-old woman comes for consultation regarding facial laser resurfacing. Physical examination shows Fitzpatrick Type III skin with facial dyschromia. Which of the following is the most likely side effect of fractional carbon dioxide laser resurfacing in this patient?

A ) Contact dermatitis
B ) Dermal scarring
C ) Ectropion
D ) Hyperpigmentation
E ) Rosacea

Answer 45

The correct response is Option D.

Pigmented skin, Fitzpatrick Type III or IV, tends to absorb about 40% more laser energy than nonpigmented skin. Thermal damage can extend beyond the area of treatment. For these reasons, physicians should be aware of the side effects and complications of ablative laser treatment in pigmented skin.

The most common side effect is hyperpigmentation. Hyperpigmentation usually occurs within 6 weeks to 6 months following laser ablation and is present in 100% of darkly skinned patients. Hyperpigmentation is most often transient and can persist for 9 months to 1 year. Recommended treatment is hydroquinone.

Contact dermatitis can occur secondary to topical antibiotic therapy such as neomycin or bacitracin. Less common side effects include dermal scarring, herpetic infections, or ectropion.

Question 46

A 16-year-old girl presents to the plastic surgery clinic with hypervascular, erythematous burn scars on her neck and chest, sustained from a scald injury one year ago. The scars are immature and causing significant psychosocial distress due to their appearance. The patient desires a noninvasive treatment option to improve the erythema and overall appearance of the scars. Which laser is the most appropriate for managing this patient’s burn scars?

A. Pulsed-dye laser
B. Ruby laser
C. Alexandrite laser
D. Fractional carbon dioxide laser
E. Nd:YAG laser

Answer 46

Correct Answer: A. Pulsed-dye laser

The pulsed-dye laser (PDL) is the most appropriate treatment for hypervascular, erythematous burn scars in this patient. This laser emits light at a 585-nm wavelength, which specifically targets hemoglobin in hypervascular tissue. It is particularly effective in treating immature burn scars by reducing erythema and improving scar quality through selective photothermolysis of blood vessels.

Explanation of Other Laser Options:
• Ruby laser (694-nm wavelength): Targets melanin and is typically used for pigmentary conditions like freckles, melasma, or tattoo removal, not for burn scar erythema.
• Alexandrite laser (720-780 nm): Also targets melanin, often used for hair removal or pigmentary disorders, but is not effective for hypervascular scars.
• Fractional carbon dioxide (CO2) laser (10,600 nm): Targets water in the skin and is used for ablative resurfacing and collagen remodeling, often for mature hypertrophic scars or skin rejuvenation. However, it is not specifically suited for treating hypervascular erythematous scars in the early stages of healing.
• Nd:YAG laser (1,064 nm): Targets deeper vascular structures but is less effective for superficial erythema compared to the PDL.

Using a PDL in this case would address the patient’s concerns by reducing the vascular component of the scars, thereby improving both appearance and symptoms like itching or discomfort.