CO2 lasers can be employed to treat a number of dermal growths. Adenoma sebaceum, trichoepitheliomas, syringomas, hidrocystomas, neurofibromas, myxoid cysts, sebaceous hyperplasia, syringocystadenoma papilliferum, and xanthelasma have all been treated with laser ablation. Though the lesions that are discussed below may seem to be disparate conditions with various etiologies including eccrine, pilar, sebaceous tumors, cysts and cholesterol
Figs 2.18A to C: (A) A case of a compound melanocytic nevi. Plan to treat with a
ultrapulse CO2; (B) Clean ablation using 250 mJ. Note the lack of thermal damage; (C) Post-operative appearance after 7 days
A B
deposition disorders, they are discussed here as they are essentially benign, acquired and largely dermal in nature. Also see Chapter 12 for other indications.
Principles
1. For individual lesions, the growth is vaporized by using relatively low- power settings in the 3- to 5-W range with a spot size that “matches the size of the lesion”.
2. Though the approach depends upon the depth of the lesion being treated, the entire lesion should not be destroyed. Ablation should be carried out but to the level of the dermis since residual thermal damage will extend 0.5 to 1 mm beyond the level of ablation. Thus one should not try to remove the entire lesion.
3. If there is deep extension of the lesion recurrence may occur.
4. A useful endpoint is a smooth cutaneous contour matching the surrounding skin.
a. Adenoma Sebaceum
Er:YAG and Cw and UltraPulse lasers have been used to treat these lesions, though the latter is better in our opinion.
Settings: One can use the CO2 laser with a low power of 2–3 W and 1–2 mm
spot size with short application times of 0.25–0.5 s to gently vaporize/heat the papules so that they shrink over the subsequent few weeks. Though the PDL has been used, the CO2 laser shows superior cosmetic results.
b. Neurofibromas
As this condition has a dermal component, the CO2 is preferred.
Step by Step Approach
1. UltraPulse laser, 1–3 mm spots with pulse energies ranging from 200 to 500 mJ, can be used.
2. After reaching dermis, the tumor, which has a rubbery consistency, can be manually expelled by gentle pressure around the wound.
3. This is followed by additional passes of the laser to destroy the base. 4. Another approach is by using the cutting mode (0.2 mm spot) to excise
the stalks of the pedunculated lesions. c. Pearly Penile Papules
An ablative pulsed or repeat mode CO2 is a very useful technique as it can help minimize the bleeding.
A setting of 1–3 W, 0.25–0.5 s exposures in the repeat mode or a 5 W, 0.1 s burst is a useful method of achieving satisfactory results.
d. Syringoma
Step by Step Approach
Surgical plan—end point is the ablation of syringoma to a depth just beneath the surrounding uninvolved skin surface. A conservative end point is removing about half to two-thirds of the lesion. This results in a depression the skin that heals with minimal hypopigmentation and scarring.
1. Demarcate the syringoma with a surgical marking pen. 2. Infiltration anesthesia is required.
3. Place normal saline or sterile water soaked sponges and drapes around the treatment area. This is primarily as the ablative lasers are absorbed by water and this can minimize damage to the surrounding skin in case of inadvertent laser impaction.
4. Either the Er:YAG or CO2 can be used.
CO2 power 15 W, (repeat continuous, pulsed or scanned beam at 0.1–0.2 s), spot size (defocused beam with spot size of 2–3 mm at skin surface). The spot size may be adjusted manually with the diameter of the lesion.Er:YAG : 5 J/cm2, two or three passes.
5. Vaporization—direct the shuttered beam to the lesion with one or two pulses. Debride the treated area with a normal saline or sterile water soaked sponge. Repeat vaporization and debridement, as necessary to reach desired end point.
Pearls/Pitfalls
1. Hypopigmentation is a inevitable though reversible sequelae and the patient should be forewarned about it (see Atlas).
2. Patients with infraorbital pigmentation should not be treated as the pigmentary consequences are disastrous.
3. Always do a test site with one or two lesions prior to treating an entire area.
e. Seborrheic Keratoses
Again the Er:YAG is superior to the CO2 laser as its has a minimal thermal damage and almost perfect epidermal ablation (Fig. 2.19).
Settings
Er:YAG (2–5 J/cm2): End point is epidermal ablation. A whitish hue is
achieved by a single pass, this can be wiped off till a faint erythema appears which indicates the papillary dermis
CO2: Either a “single spot” Cw or UltraPulse modes can be used.
Care should be taken near the base of the lesion so that unnecessary heating and subsequent pigmentation changes and scarring do not occur. This almost never occurs with the Er:YAG laser, which is a reason for our preference for using this system
f. Sebaceous Hyperplasia
This is one of the most rewarding and easy tumors to treat. It is our opinion that for these the Er:YAG is an excellent tool and we prefer it over CO2 laser.
Settings: Er:YAG (2–3 mm spot; 4–5 J/cm2). CO
2 (1 mm handpiece; pulse
energy of 200 mJ), the distance between the skin and handpiece tip is varied to accommodate the size of the lesion.
Step by Step Approach
1. A few overlapping passes are made to expose the yellow fatty nodules. 2. Once exposed, these punctate 0.5 mm lobules are treated with additional
pulses until they are either extruded are heated.
3. The final result is a slight depression that resolves in 1–3 months. g. Steatocystomas
The principle is to treat the lining of the cysts otherwise rapid recurrence is
the rule.
Figs 2.19A and B: (A) Seborrheic keratosis on the face. Plan to treat with Er:YAG;
(B) Postoperative view after 7 days, note the clean surface with little sign of PIH
Step by Step Approach
1. First pierce the central portion with the 1 mm spot in the pulsed mode (Repeat pulse).
2. Apply gentle pressure to the lesion to extrude the contents. 3. Apply a defocused laser passes to the lining.
4. Another alternative if the lesion are small is to vaporize the lesions with subsequent passes.
5. The wounds are allowed to heal by secondary intention. h. Trichoepitheliomas
Er:YAG and Cw and UltraPulse lasers have been used to treat these lesions. End point: A ablation to a level just below the adjacent skin surface should be the goal. Deeper ablation results in scarring and more superficial ablation results in early recurrence.
Settings: The typical laser settings in Cw mode include 1–3 mm spot sizes and powers of 2–5 W. If a UltraPulse mode is used, 200–250 mJ energy is used. It is our experience that a modulated Er:YAG can achieve excellent results with minimal thermal damage
i. Xanthelasma
This common condition has been treated by multiple modalities including surgery, TCA and lasers. Clinically the flat, papular, plaque and nodular variants have been described. The importance being that for the last two variants the depth of infiltration makes them unresponsive to most methods except surgery.
1. Surgery: There are various techniques that can be used but inspite of
them recurrences are commonly seen. Moreover, it is impractical to employ surgical means for recurrences, which are seen in the deeper variants. We recommend surgery for a few, large lesions (plaques/ nodular) with a appreciable depth.
2. TCA: There are two important principles that determine the use of TCA.
First the concentration that should be used should be at least 30-70% and secondly it is to be used in small lesions, with little depth. Moreover a minimum of 3-5 sessions are required for most lesions
3. Laser: Though various lasers have been used, the ablative lasers are
superior to Nd:YAG, PDL, ruby and fractional lasers. Both CO2 and Er:YAG can be used though the latter has a problem with the lack of coagulation that leads to a decrease in the achievable depth and that may lead to recurrences. As shown in the Figure 2.20 coagulative effect of CO2 is ideal though in deeper lesions a residual lesion can still remain.
Step by Step Approach (Fig. 2.21)
1. Our approach is to use the 1–2 mm handpiece with either the UltraPulse or Er:YAG laser.
2. A defocussed beam is used to initially ablate the epidermis.
3. This reveals the “fat” tissue. As the normal dermis is replaced by the fat tissue the normal signs that determine the depth are not readily visible. 4. With the Er:YAG it is a good “trick” to ablate the surrounding epidermis
to give an idea about the depth achieved.
5. After ablating the epidermis, about 1–3 passes using a fluence of 10 J/cm2
with the Er:YAG is enough. Even if visible tissue remains the procedure should be stopped. With the CO2 (5 J/cm2) again 3 passes are enough
to cause sufficient ablation of the fat tissue. The residual “invisible” coagulation that extends deeper than the ablation is sufficient to help in the ultimate removal of the lesion.
Pearls/Pitfalls
Even when some “fat tissue” is visible grossly, the coagulation and fibrosis helps to remove the lesion. Excessive treatment can lead to complications, thus it is better to undertreat than to overtreat.
Fig. 2.20: A figurative depiction of the effect of CO2 laser in xanthelasma. Note that for a deep laser, recurrence can occur even though there is a coagulative component of the pulsed CO2 laser
After healing, at the next visit the residual lesion should be treated by TCA and not by the laser as the tissue depth required may be less and lead to overtreatment.
Our approach is to use the laser as a tool for both small and large lesions. For the former a single session suffices while for the latter lesion, after the initial session TCA can be used for residual lesions. If that fails surgical excision is the only option. (Flow chart 2.1). A surgeon, though may adopt a different approach.
Level of Difficulty Variable.
7. Warts