Quality-Switched Ruby Laser Treatment of Solar Lentigines and Becker’s Nevus: A Histopathological and Immunohistochemical Study

Abstract

Objective: A histopathological and immunohistochemical study was initiated to assess changes in benign human pigmented skin lesions after quality switched ruby laser (QSRL) irradiation. Method: A total of 196 solar lentigines on 8 patients’ forearms were irradiated in vivo, 13 biopsies were taken. Hematoxylin-eosin staining and immunohistochemical techniques using anti-S-100 and Fontana-Masson stainings, as well as cryosections stained with nitroblue tetra-zolium chloride (NBTC), were employed for the evaluation of the specimens. Results: Immediately after QSRL impact selective photothermal damage (vacuolization) of all pigmented epidermal and basal melanocytes, keratinocytes, superficial dermal melanocytes and melanophages could be observed in solar lentigines. Cryosections stained with NBTC featured minimal thermal damage of the surrounding tissue. One Becker’s nevus was also exposed to the QSRL, biopsies were taken before and immediately after QSRL exposure. In this lesion, superficially located pigments were selectively damaged, but a fair amount of pigmented cells in adnexal structures persisted throughout this single course of QSRL treatment. Recurrence of lentigines was not observed. In Becker’s nevus, following initial fading of the lesion, clinically reactive hyperpigmentation occurred 4 weeks later. Conclusion: We found that pigmented lesions featuring a moderate amount of pigment exclusively in and around the basal cell layer, like solar (actinic) lentigo, can be successfully removed by a single QSRL exposure selectively damaging epidermal and basal pigmented structures. Further investigations concerning QSRL treatment of dermally pigmented skin lesions have to be initiated.

Improved staining method for determining the extent of thermal damage to cells

“…We and other authors [1][2][3][4][5][6][7][8] have used enzyme histochemistry to evaluate thermal damage immediately following irradiation. Thermal damage to cells results from the denaturation of biomolecules.…”

“…In order to limit the number of animals used in experiments and to increase the speed at which experiments can be completed, there is a need for methods that do not require the survival of the animals after the treatment. For laser-induced thermal damage, we and others [1][2][3][4][5][6][7][8] have used enzyme histochemical stains of tissue as an immediate method to assay for cell viability in tissue. This method shows decreased to absent staining when there has been thermal denaturation of many globular proteins.…”

Pseudo-Melanoma after Laser Therapy

“…Especially for pigmented lesions this development [8, 14, 15, 16, 17, 18] is accompanied by significant dangers for the patient. The exact clinical classification of a pigmented lesion even by an experienced dermatologist who is also applying dermatoscopy carries a significant risk of clinical misdiagnosis.…”

Pigmente Lezyonlarda Lazer

“…Ancak pigmentasyonla beraber hipertrikozisin izlendiği lezyonlarda Q-anahtarlı lazerlerle yapılan tedaviler yetersiz düzelme, hipopigmentasyon ve rekürrens ile sonuçlanmaktadır. Bunun nedeni yüzeysel yapılardaki pigmentlerin Q-anahtarlı lazerlerle temizlenmesine karşın adneksiyel yapılarda belirgin düzeyde pigmentin kalmasıdır 25 . Günümüzde Becker nevüsün tedavisinde en iyi yaklaşım epidermal melaninin temizlenmesi için Q-anahtarlı lazerin ve hipertrikozun temizlenmesi için uzun atımlı Nd:YAG, alexandrite veya diode lazerlerin kombine olarak kullanılmasıdır 26 .…”