Inservice Exam - 2005
Laser

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



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.


References:
1. Ruiz-Rodriquez R, Sanz-Sanchez T, Cordoba S. Photodynamic photorejuvenation. Dermatol Surg. 2002;28(8):742-744.
2. Goldman MP, Boyce SM. A single-center study of aminolevulinic acid and 417 nm photodynamic therapy in the treatment of moderate to severe acne vulgaris. J Drugs Dermatol. 2003;2(4):393-396.
3. Alexiades-Armenakas MR, Geronemus R. Laser-mediated photodynamic therapy of actinic keratoses. Arch Dermatol. 2003;139:1313-1320.




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


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.


References:
1. Alster TA. Laser treatment of tattoos. In: Alster TA, ed. Manual of Cutaneous Laser Techniques. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2000:71-88.
2. Adrian RM, Griffin L. Laser tattoo removal. Clin Plast Surg. 2000;27:181-192.




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

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.

References:
1. Burrows PE. Urgent and emergent embolization of lesions of the head and neck in children: indications and results. Pediatrics. 1987;80(3):386-394.
2. Han MH, Seong SO, Kim HD, et al. Craniofacial arteriovenous malformations: preoperative embolization with direct puncture and injection of n-butyl cyanoacrylate. Radiology. 1999;211:661.
3. Kohout MP, Hanson M, Pribaz JJ, et al. Arteriovenous malformations of the head and neck: natural history and management. Plast Reconstr Surg. 1998;102:643.
4. Persky MS. Congenital vascular lesions of the head and neck. Laryngoscope. 1986;96:1002.





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

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.


References:
1. Tallman B, Tan OT, Morelli JG, et al. Location of port-wine stains and the likelihood of ophthalmic and/or central nervous complications. Pediatrics. 1991;87(3):323-327.
2. Mills CM, Lanigan SW, Hughes J, et al. Demographic study of port wine stain patients attending a laser clinic: family history, prevalence of naevus anaemicus and results of prior treatment. Clin Esp Dermatol. 1997;22(4):166.
3. Goldman MP, Fitzpatrick RE, Ruiz-Esparza J. Treatment of port-wine stains (capillary malformation) with the flashlamp pumped pulsed dye laser. J Pediatr. 1993;122:71.



Which of the following light sources is noncoherent?

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

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.

References:
1. Raulin C, Greve B, Grema H. IPL technology: a review. Lasers Surg Med. 2003;32(2):78-87.
2. Weiss RA, Weiss MA, Beasley KL. Rejuvenation of photoaged skin: 5 year results with intense pulsed light of the face, neck, and chest. Dermatol Surg. 2002;28(12):1115-1119.