Role of Laser Therapy in Dermatology – Clinical Aspects

The impact of temperature on vascular function in connection with vascular laser treatment

Pulsed dye lasers are used effectively in the treatment of psoriasis with long remission time and limited side effects. It is, however, not completely understood which biological processes underlie its favorable outcome. Pulsed dye laser treatment at 585-595 nm targets hemoglobin in the blood, inducing local hyperthermia in surrounding blood vessels and adjacent tissues. While the impact of destructive temperatures on blood vessels has been well studied, the effects of lower temperatures on the function of several cell types within the blood vessel wall and its periphery are not known. The aim of our study is to assess the functionality of isolated blood vessels after exposure to moderate hyperthermia (45 to 60°C) by evaluating the function of endothelial cells, smooth muscle cells, and vascular nerves. We measured blood vessel functionality of rat mesenteric arteries (n=19) by measuring vascular contraction and relaxation before and after heating vessels in a wire myograph. To this end, we elicited vascular contraction by addition of either high potassium solution or the thromboxane analogue U46619 to stimulate smooth muscle cells, and electrical field stimulation (EFS) to stimulate nerves. For measurement of endothelium-dependent relaxation, we used methacholine. Each vessel was exposed to one temperature in the range of 45-60°C for 30 seconds and a relative change in functional response after hyperthermia was determined by comparison with the response per stimulus before heating. Non-linear regression was used to fit our dataset to obtain the temperature needed to reduce blood vessel function by 50% (Half maximal effective temperature, ET50). Our findings demonstrate a substantial decrease in relative functional response for all three cell types following exposure to 55°C-60°C. There was no significant difference between the ET50 values of the different cell types, which was between 55.9°C and 56.9°C (P>0.05). Our data show that blood vessel functionality decreases significantly when exposed to temperatures between 55°C-60°C for 30 seconds. The results show functionality of endothelial cells, smooth muscle cells, and vascular nerves is similarly impaired. These results help to understand the biological effects of hyperthermia and may aid in tailoring laser and light strategies for selective photothermolysis that contribute to disease modification of psoriasis after pulsed dye laser treatment.

Telangiectasias: Small lesions referring to serious disorders

Telangiectasias are prominent small vessels (venules, capillaries or arterioles) that are visible as small red-purple focal lesions in the skin and mucous membranes. They can serve as a cutaneous marker for a number of primary (mostly hereditary) disorders and they can be secondary to other (systemic) diseases. Patients with telangiectasias are seen by general health practitioners, pediatricians, (pediatric) neurologists, dermatologists, and ophthalmologists. In this article we give an overview of the different disorders in which telangiectasias are a prominent feature, focusing on neurocutaneous disorders in which they serve as a marker for establishing the right diagnosis. The pattern of distribution of the telangiectasias, their age of onset and associated features are helpful to distinguish between the different disorders.

A Review of the Principles and Use of Lasers in Lower Limb Problems

Lasers present a unique light source with many clinical uses including a number of applications relevant to the lower extremity. In this article, the basic principles of lasers and their interactions with tissue will be reviewed. The article examines laser applications in skin and vascular disease including wound healing. The principles of laser safety are discussed, and relevant future developments are considered.

Melanoma diagnosed in lesions previously treated by laser therapy

Laser therapy has become a routine procedure in dermatological practice and is frequently also used for pigmented lesions. Few reports exist of melanomas diagnosed in lesions previously treated by laser therapy. Between 2007 and 2014, we identified 11 patients who presented to our department with a melanoma diagnosed in a region previously treated by laser therapy. The course of events until the diagnosis of melanoma was assessed as well as patient outcome including treatment for disease progression. No histological assessment had been performed prior to laser therapy in nine of 11 (82%) cases. Benign melanocytic lesions had been diagnosed by biopsy prior to laser therapy in the other two cases. Time from laser therapy to diagnosis of melanoma ranged from less than 1 to 10 years. Stage of disease at diagnosis varied from stage IA to IIIC. Four patients progressed to stage IV disease, of whom at least one died of melanoma. We conclude that laser treatment of pigmented lesions can complicate the diagnosis of melanoma and lead to diagnosis delay with potentially fatal consequences. Considering this risk, we believe laser therapy for pigmented lesions should either be avoided entirely or at a minimum performed only after prior histological assessment.

Effects of femtosecond laser irradiation on osseous tissues

BACKGROUND AND OBJECTIVE

Few studies have investigated femtosecond (fs) lasers for cutting bone tissue.

STUDY DESIGN/MATERIALS AND METHODS

A 775 nm, 1 kHz, 200 femtosecond, up to 400 microJ laser system was used to irradiate in vitro calcified cortical bone samples and bone tissue culture samples.

RESULTS

The ablation threshold in cortical bone was 0.69+/-0.08 J/cm(2) at 775 nm and 0.19+/-0.05 J/cm(2) at 387 nm. Plasma shielding experiments determined that the ablation plume and the plasma significantly affect material removal at high repetition rates and appear to generate thermal transients in calcified tissue. Confocal analysis revealed intact enzymatic activity on the surface of cells immediately adjacent to cells removed by fs laser irradiation.

CONCLUSIONS

These experiments demonstrate that fs lasers used for bone tissue cutting do not appear to generate significant temperature transients to inactivate proteins and that cellular membrane integrity is disrupted for only a few cell layers.

SACRAL syndrome: spinal dysraphism, anogenital, cutaneous, renal and urologic anomalies, associated with an angioma of lumbosacral localization

BACKGROUND

Publications concerning perineal infantile hemangiomas are scarce, and comprise no large series.

OBJECTIVE

Studying clinical features of hemangiomas of the perineal area, complications and associated malformations.

METHODS

Retrospective analysis of all hemangiomas localized in the perineal area, encountered at the Children's Hospital in Bordeaux from 1994.

RESULTS

Of 49 perineal hemangiomas (34 girls, 15 boys), 5 patients had accompanying malformation, mainly lipomyelomeningocele with tethered cord. The superficial hemangiomas were more represented in males and presented sooner than the nodular counterpart. The average rate of ulceration was 73%, ulcerations developed earlier in the superficial forms than their nodular counterparts (2 vs. 4 months).

CONCLUSION

Superficial perineal hemangiomas are more often complicated by ulceration, and are associated with developmental anomalies. As a counterpart for the PHACE syndrome in facial hemangioma, we propose the acronym SACRAL for perineal hemangiomas: Spinal dysraphism, Anogenital anomalies, Cutaneous anomalies, Renal and urologic anomalies, associated with Angioma of Lumbosacral localization.

Laser therapy of vascular lesions

Since the first construction of a laser by Maiman in 1960 and the first clinical application of a laser in the therapy of skin lesions by Leon Goldman, laser therapy has become an important therapeutic modality in dermatology. Various lasers can be used for the treatment of different vascular and non-vascular lesions. According to our results, vascular lesions constitute the most important indication for laser therapy in dermatology.

Treatment of angiokeratoma of Fordyce with pulsed dye laser

BACKGROUND

Angiokeratomas of Fordyce are typically asymptomatic vascular lesions characterized by blue-to-red papules with a scale surface, most often located on the scrotum. Although considered benign, the lesions may bleed, either spontaneously or secondary to rupture, leading to patient anxiety and social embarrassment.

OBJECTIVE

The objective was to determine the safety and effectiveness of 585-nm pulsed dye laser for the treatment of angiokeratomas of Fordyce.

METHODS

Twelve patients with Fitzpatrick skin type II to IV were treated for angiokeratomas of Fordyce with pulsed dye laser (5.5-8.0 J/cm(2)) in two to six sessions. Lesion clearance was evaluated by two specialists on the basis of digital photographs taken before the first treatment and 2 months after the last treatment.

RESULTS

Seven patients had an excellent response (clearance rating 75%-100%) and five patients had a good response (clearance rating 50%-75%). Transient purpura and pain were present in all patients. Bleeding during treatment occurred in five patients. There were no permanent side effects.

CONCLUSION

Pulsed dye laser is effective and safe for the treatment of angiokeratoma of Fordyce, with minimum side effects, providing an additional nonablative therapeutic option.

Excimer Laser versus Narrow-Band UVB (311 nm) in the Treatment of Psoriasis Vulgaris

BACKGROUND

The excimer laser is a new therapeutic option in the treatment of psoriasis vulgaris.

OBJECTIVE

The purpose of this study was to determine the response of psoriasis lesions to the 308-nm excimer laser compared to 311-nm UVB phototherapy.

METHODS

In this prospective right/left comparative, open, single-blinded trial, selected psoriasis plaques of 16 patients were treated with the excimer laser whereas the rest of the body was treated with UVB narrow-band phototherapy. A modified PASI score was used to evaluate the results.

RESULTS

After 12 treatments, 15 patients were evaluated. In 2 patients no difference between the two body sides was observed. In 9 patients the laser-treated lesions showed better results, whereas in 4 patients the side treated with 311-nm UVB showed more clearing. The mean reduction in PASI score was 5.6 and 4.9, respectively (difference not significant).

CONCLUSION

The use of the 308-nm xenon chloride excimer laser is an additional effective therapeutic option for the treatment of psoriasis vulgaris.

Metastasis of a malignant melanoma 2 years after carbon dioxide laser treatment of a pigmented lesion: case report and review of the literature

A 64-year-old woman with a clinically diagnosed 'lentigo simplex' on her right cheek was dermatologically treated several times with a CO2 laser. Three years later she showed a metastasis of a malignant melanoma in her right parotid gland. Considering this case, as well as other published cases reporting malignant melanomas occurring after laser treatment, we again underscore that naevomelanocytic lesions are not a routine indication for laser treatment.