ARTICLE
Auteur(s) : Engin
Sezer1, Hakan Erbil2, Zafer
Kurumlu2, Halis Bülent Taştan2, Ilker
Etikan3
1Department of Dermatology, Gaziosmanpasa University
School of Medicine Tokat, 60100, Turkey
2Department of Dermatology, Gulhane Military School of
Medicine, Ankara, Turkey
3Department of Biostatistics, Gaziosmanpasa University
School of Medicine Tokat, Turkey
accepté le 5 Septembre 2006
Solar lentigo is a benign pigmented lesion that commonly occurs on
the sun-exposed areas such as the face, neck, hands, and forearms.
Solar lentigo is usually observed in fair-skinned Caucasians
between the fourth and sixth decades of life. The lesions are
characterized by round or oval, irregularly shaped hyperpigmented
macules, varying in size from a few millimeters to one centimeter
or more [1, 2]. The coloration varies from yellow-brown to dark
brown. Histologically, an elevated melanin content in the
melanocytes and basal keratinocytes, and irregular elongation of
the rete ridges are observed. Focal excess in the eumelanin load
secondary to uneven distribution and synthetic activity of
melanocytes induced by ultraviolet irradiation has been implicated
in the pathogenesis of solar lentigo [3].Various treatment
modalities including chemical peels, cryosurgery, laser surgery,
dermabrasion, and topical bleaching agents have been indicated to
treat solar lentigo [1, 3-6]. A medium-depth chemical peel regimen
using 70% glycolic acid plus 35% trichloroacetic acid (TCA) is an
effective treatment method for pigmentary dyschromias of
actinically damaged non-facial skin, although complications such as
pain and scarring limits its use [4, 7]. Recently focal chemical
peel with TCA has been introduced for the treatment of pigmentary
disorders and atrophic acne scars, to reduce the risk of
hypopigmentation and scarring [8, 9].The aim of this study was to
evaluate the safety and efficacy of a focal medium-depth chemical
peel regimen with glycolic acid plus TCA for the treatment of solar
lentigines of the hands and to compare with cryosurgery. To the
best of our knowledge, this is the first study investigating the
effectiveness of a focal medium-depth chemical peel for the
treatment of solar lentigo.
Patients and methods
Study population
Twenty-five subjects (8 male, 17 female), ranging in age from 44 to
72 years, participated in the study. The inclusion criteria
required a diagnosis of solar lentigines of the hands with clinical
findings of brownish-coloured pigmented macules which occurred
after adolescence and increased in number with higher age.
Dermoscopic examination (Delta 10, Heine, Germany) was also carried
out to rule out malignant melanoma.
The exclusion criteria included topical treatment with bleaching
agents within the last 2 months and any history of prior cosmetic
surgery, hypersensitivity to glycolic acid or TCA, Raynaud’s
disease, cryoglobulinemia, cold urticaria, and keloidal tendencies.
The study was approved by the local ethical committee and all the
patients gave written informed consent before enrolment.
Study design
This investigation was designed as a randomized, controlled, paired
study based on a left to right comparison pattern, to compare the
efficacy of focal medium-depth chemical peel and cryosurgery.
Treatment with focal medium-depth chemical peel and cryosurgery was
randomly assigned to the left or right hand using a computer-based
program. Focal medium-depth chemical peel with 70% glycolic acid
and 35% TCA was applied to solar lentigines of one hand of the
patient and cryosurgery was performed for the other hand. The
colour photographs were taken before treatment and 2 months after
the treatment period using a Nikon D70 camera with a macro lens
from a distance of 25 cm. Two SB-30 Nikon flashes positioned
at a 45-degree angle were used against a black unlit background.
Treatment procedures
All patients were instructed to apply 0.05% tretinoin cream (Tretin
cream 0.05%, Triax pharmaceuticals, US) to both sides of the hands
every night for 3 weeks before the treatment. Focal medium-depth
chemical peel and cryosurgery was performed by the same
investigator (E. S.). Patients were advised to protect their hands
from sun exposure and use sunscreens in daytime for a 2 month
period after the treatment.
The hand to be treated with chemical peel was cleansed with
acetone. Using a cotton-tipped applicator, unbuffered 70% glycolic
acid solution (Neostrata 70% solution, US) was applied focally to
solar lentigines of the hand for 2 minutes and then neutralized
with 10% sodium bicarbonate solution. Next, 35% TCA wt/vol solution
(Sigma-Aldrich, US) was applied focally to the lesions using a
cotton-tipped applicator until a uniform white frost was achieved,
and then neutralized with tap water. After the chemical peel, the
patients were instructed to apply mupirocin ointment twice a day
until peeling was completed.
Cryosurgery was performed using a jet spray (Brymill CRY-AC, US)
with a 0.4 mm tip size for 2-5 seconds after initial freezing
of each lesion from a distance of 3 cm.
Determination of clinical response
For independent clinical assessment, three blinded investigators
examined the pre-treatment and 2-month post-treatment photographs
and graded the clinical response using a 5-point grading scale
determined by Todd et al. [10]: poor, 0% to 25%; fair, 26% to 50%;
good, 51% to 75%; excellent, 76% to 90%; and clear, 91% to 100%.
Assessment of pain
The patients were asked to assess the pain for each treatment
modality with a pain scale varying between 0 (none) to 10
(maximum).
Statistical analysis
Assessment of statistical significance of clinical improvement
within both treated sides was performed on the basis of chi-square
test. Analysis of pain scores for chemical peel and cryosurgery
treated sides were plotted according to chi-square test. The Z test
was used to determine the significance of post-treatment
complications such as hypopigmentation between the chemical peel
and cryosurgery treatments. Significance was defined as
p < 0.05.
Results
Twenty-three of the original 25 patients completed the study. Two
patients were lost to follow-up for post-treatment evaluation. The
results of clinical improvement in each treatment modality are
shown in table 1( Table 1 ) and ( figure 1 ).
In the focal medium-depth chemical peel treated side, clearing
was achieved in 17.4% of patients. In the cryosurgery treated side,
clearing was achieved in 21.7% of patients. Statistically, the
differences between the clinical improvement of solar lentigines
with chemical peel and cryosurgery was not significant
(χ2 = 0.786, p = 0.940, chi-square test).
Pain scores were found to be lower in the focal medium-depth
chemical peel treated side, compared with cryosurgery treated side,
according to the chi-square test (χ2 = 22.319,
p = 0.004).
No scarring was detected with both treatments. In the
cryosurgery treated side, hypopigmentation was observed in six out
of 23 patients (26.1%), compared with one out of 23 patients (4.3%)
in the chemical peel treated side (as shown in ( figure 2 )). The risk of
development of post-treatment hypopigmentation was significantly
reduced with focal medium-depth chemical peel compared with
cryosurgery (Z test for the difference between sample portions,
p = 0.046).
Table 1 Results of clinical improvement of solar
lentigines at 2-months following focal medium-depth chemical peel
and cryosurgery
|
Clinical improvement
|
Chemical Peel (n = 23)
|
Cryosurgery (n = 23)
|
|
Clear
|
4 (17.4%)
|
5 (21.7%)
|
|
Excellent
|
10 (43.5%)
|
10 (43.5%)
|
|
Good
|
7 (30.4%)
|
5 (21.7%)
|
|
Fair
|
1 (4.3%)
|
2 (8.7%)
|
|
Poor
|
1 (4.3%)
|
1 (4.3%)
|
Discussion
In this study, the clinical results of a focal medium-depth
chemical peel technique using 70% glycolic acid and 35% TCA for the
treatment of solar lentigines of the hands was comparable to that
of cryosurgery. A recent study comparing the efficacy of chemical
peel with 30% TCA with cryosurgery for the treatment of solar
lentigines showed cryosurgery to be superior to TCA peels [11]. The
better results obtained in our study may be explained with the
depth of the chemical peel that we use. The clinical results of a
chemical peel regimen has been considered to correlate with the
depth of the histological changes exerted by the peel [7].
Medium-depth chemical peels are defined as the application of
peeling agents to produce a dermal wound to the level of papillary
dermis and upper reticular dermis. Medium-depth chemical peels are
indicated for the treatment of pigmentary alterations such as solar
lentigines, superficial rhytides, and for the removal of the
actinic keratoses and acne scars [4, 12]. TCA, a chemical agent
that causes epidermal necrosis by protein precipitation, produces
superficial peeling when used in strengths from 10% to 35%.
Combination of solid CO2, Jessner’s solution, and 70%
glycolic acid along with a 35% TCA formula results in a
medium-depth chemical peel. As in our study, glycolic acid causes
detachment of keratinocytes and epidermolysis when applied prior to
TCA, thus allowing deeper and more even penetration of the TCA
solution [13].
Recently, Chun et al. introduced a focal chemical peel technique
for the treatment of pigmentary skin diseases including solar
lentigines, seborrheic keratosis and melasma. The authors had used
focal application of 50 to 65% TCA solution by pressing firmly a
sharpened wooden applicator to the pigmented lesions [8]. A good
clinical response was achieved in 82% of the patients without
significant complications at the treatment sites. The authors
suggest that this technique can avoid scarring and reduce the risk
of developing hypopigmentation by sparing the adjacent normal skin
and adnexal structures. In another study, focal treatment of acne
scars with the same technique had resulted in good clinical
response in the majority of the patients [9]. Compared with these
studies, our technique is unique in that we performed focal
application of 70% glycolic acid and 35% TCA by using cotton-tipped
applicators to obtain a level of medium-depth chemical peel. The
results were comparable to that of cryosurgery with optimal patient
tolerance and minimal side effects.
One major concern with the use of TCA chemical peeling is the
potential tumorigenesis of TCA. Dainichi et al. showed an increase
in the rate of tumor development on the skin areas of hairless mice
undergoing ultraviolet B (UVB) irradiation treated with 35% TCA,
compared with the non-treated areas [14]. The authors suggest that
TCA chemical peel may increase the risk of mutations leading to
tumorigenesis. On the other hand, a statistically significant
change in the expression of p53, which is a tumor suppressor
protein, has not been detected in facial skin treated with
superfical 10-30% TCA chemical peeling [15]. Another study showed a
reduction in the number of epidermal Langerhans cells of the normal
human skin subject to 40-60% TCA chemical peeling, indicating a
temporary impairment of the skin defence system with TCA peeling,
which may result in cutaneous carcinogenesis [16]. These data
suggest that patients treated with long-term and frequent TCA
chemical peeling should be monitored for the development of skin
cancer.
Post-treatment hypopigmentation is a common side effect of
cryosurgery [1]. We claim that the treatment of solar lentigines of
the hands with focal medium-depth chemical peel has some additional
advantages over cryosurgery such as being a less painful procedure
and with a diminished risk of hypopigmentation, although
cryosurgery is less time-consuming compared with this
technique.
In summary, we conclude that focal medium-depth chemical peel
with 70% glycolic acid plus 35% TCA may be considered as an
efficacious and safe method for the treatment of solar lentigines
of the hands.
Acknowledgements
Financial support: None. Conflict of interest: None.
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