Use Of The Argon Pumped Tunable
Dye Laser For Cutaneous Lesions

John B. Harris, M.D. and Henry W. Randle, M.D.

John B. Harris, M.D. is with the Department of Plastic Surgery at Mayo Clinic Jacksonville.
Henry W. Randle, M.D. is with the Department of Dermatology at Mayo Clinic Jacksonville.

The argon pumped tunable dye laser (A.P.T.D.L.) is a liquid medium laser that can be "tuned" to generate wavelengths of coherent light desirable for the treatment of skin lesions. An ionized gas (argon) laser is used to "pump" the liquid medium to generate a continuous laser beam output. This is in distinction to "pulsed" dye lasers that are pumped by intense flash lamps, and generate a pulsed mode output.

The wavelengths produced by the A.P.T.D.L. include a yellow-band at 585 nanometers¹ which is selectively absorbed by oxyhemoglobin, the principal chromophore in oxygenated blood. This feature permits targeted treatment for vascular lesions like telangiectases or port-wine stains. The argon pumped tunable dye laser can also produce blue-green bands at 480 to 532 nanometers. Selective absorption of these wavelengths by melanin permits the directed treatment of benign melanotic lesions like lentigines. Thus, the principal clinical application of the A.P.T. dye laser is to treat cutaneous vascular disorders and pigmented lesions with minimal or no danger to the epidermis.

Organic compounds dissolved in solvents are the active molecules in all dye lasers. These dyes absorb strongly in various portions of the visible spectrum to produce colored light. Since the visible spectrum wavelengths of these lasers can easily be transmitted via flexible and other optic devices², therapy of a wide range of lesions may be obtained by techniques varying from hand held tracing of facial telangiectasias to robotic scanning (Hexa-scan) of large surface area port wine stain hemangiomas and widespread facial telangiectatic markings as in acne rosacea. Other indications are shown in Table 1. The A.P.T.D.L. is not very effective for telangiectasias of the extremities, thick boggy hemangiomas or hemangiomas in children.

Applications in Cutaneous Vascular Lesions

To trace individual vessels and produce "heat sealing" of the vessel with little nonspecific thermal damage of the surrounding normal tissue, the A.P.T.D.L. is generally used at a setting of 585 nanometers, 0.1 to 1 mm spot size, and 0.4 to 0.6 watts power. Overlying skin and melanocytes are relatively impervious to laser light at this wavelength. Therefore, selective injury to the blood vessels, but not adjacent tissue, occurs. Anesthesia is usually not required although EMLA (lidocaine and prilocaine transcutaneous anaesthetic) may be applied topically under occlusion one to two hours prior to the procedure. Sublingual Valium (5 to 10 mg) may be given preoperatively. The A.P.T.D.L. may take longer to achieve results than the flash-pumped yellow light laser but it produces less pain, less post-operative erythema, and no purpura. Blistering or crusting that may occur in the few days post-operatively is covered with antibiotic ointment to keep the area soft and to aid reepithelialization.

Most face and trunk telangiectasias including spider angiomas respond extremely well to tunable dye laser therapy. Tunable dye laser treatment has also been shown to improve the telangiectasias and erythematous component of rosacea.

Those port wine stain hemangiomas that respond best to tunable dye laser surgery are pale pink to red in color, flat, or slightly raised in surface texture. Treated skin usually retains the ability to suntan and retains normal skin mobility, elasticity, hair growth, and skin markings. The degree of improvement of the port wine stain depends on the color and thickness and location of the lesion. Between two and seven treatments of the same area may be required for final clearing and there is never total obliteration. See Figures 1-3.

	Figure 1A. 49 year old lady with a port wine stain hemangioma on the chin for approximately fifteen years. She sought treatment because of the recent onset of papules in the lesion.   Figure 1B. Same area after 3 treatments with the argon pumped tunable dye laser. Settings were 585 nm, 0.5 watts, 0.5 mm spot size.
	Figure 2A. 41 year old lady with a port wine stain hemangioma on the right temple.     Figure 2B. After one treatment with the argon pumped tunable dye laser using the handpiece. Settings were 585 nm, 0.5 watts, 0.5 mm spot size.
	Figure 3A. 83 year old lady with a port wine stain hemangioma on the right cheek present since birth.   Figure 3B. After 5 treatments with the argon pumped tunable dye laser. Initially treated with the Hexascan with settings of 585 nm, 1.5 watts, with a fluence of 21 Jules per square centimeter, for 70 milliseconds with the 13 mm. Hexascan. Subsequently, the smaller areas were treated with the handpiece, at a setting of 585 nm, 0.5 watts, 0.5 mm spot size.

Applications in Cutaneous Pigmented Lesions

Various lasers have been utilized over the years for removing cutaneous pigmented lesions. The CO2 laser in either the cutting or vaporizing mode has been an important tool for dermatologists and surgeons. The CO2 laser emits light in the infra-red band at 10,600 nm which is absorbed by intracellular water. The CO2 laser has little color selectivity and poor tissue penetrating ability which leads to more collateral tissue damage and scarring than with other lasers used to treat pigmented lesions. The Argon laser emits light with peaks at 488 and 514 nm. These wavelengths have excellent absorption by melanin, allowing for argon laser use in removing melanocytic lesions. However, due to competitive absorption of the green light by oxyhemoglobin there is considerable heat build-up which also leads to collateral tissue damage. Post-treatment hypopig-mentation, manifest as a streaking artifact in the treated area of the face, is a particular disadvantage of plain argon laser treatment in comparison with the A.P.T.D.L. The Q-switched ruby laser (694 nm) and the Q-switched Nd:YAG laser (532 nm and 1064 nm) both emit light which is absorbed well by melanin. These lasers, in addition to treating superficial pigmented lesions, have been used for removal of tattoos composed of black, blue and some red pigment.

The argon pumped tunable dye laser can be "tuned" to emit blue-green light of wavelength 480 to 532 nm with good selective absorption by melanin. The A.P.T.D.L. can be used both in the Hexascan mode or with the handpiece for management of lentigines, café-au-lait spots and other superficial pigmented lesions (Figure 4). As with treating vascular lesions, pre-treatment with EMLA cream is helpful and patients are advised that multiple treatments are usually necessary. Complete eradication of deep dermal pigment with any laser is difficult and post-treatment darkening of the deeper lesions may occur.

Figure 4A. 41 year old lady with a café-au-lait spot on the right breast.	Figure 4B. After multiple treatments with the argon pumped tunable dye laser in the green light mode with both Hexascan and handpiece.

Summary

The argon pumped tunable dye laser is a useful clinical tool for the removal or alleviation of cutaneous vascular and pigmented lesions. In the future, new lasers will continue to be developed. We anticipate they will provide for more specific treatment with improved healing characteristics.

NOTES

1. Nano = one billionth. One nanometer (abbreviated nm) is 10^-9 meters, 10^-3 microns (abbreviated mm or simply m ), or ten Angstrom Units (abbreviated A).

2. The 10,060 nanometer (far-infared) invisible output of the common CO2 laser, by comparison, must be reflected through complex hollow articulated tubes to reach its target.

3. Calcification, Raynaud's phenomenon, scleroderma, and telangiectasis syndrome, seen in acrosclerosis.

4. A smooth enduring vascular lesion, commonly found on the lip.

5. A congenital facial melanocytic lesion usually affecting the skin of the cheek, nose, or forehead, or the sclera of the eye.

SUGGESTED READING

1. Key D. Argon-pumped Tunable Dye Laser for the Treatment of Cutaneous Lesions. Clinics in Dermatology. 1995; 13: 59-61.

2. Broska P, et al. Comparison of the argon tunable dye laser with the flash lamp pulsed dye laser in treatment of facial telangiectasias. Journal Dermatologic Surgery and Oncology. 1994; 20: 749-753.

3. Lowe N, et al. Flash lamp pumped dye laser for rosacea - associated telangiectasia and erythema. Journal Dermatologic Surgery and Oncology. 1991; 17: 522-525.

February, 1998/ Jacksonville Medicine

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