Ulrich Hohenleutner

Fast and effective skin ablation with an Er:YAG laser: Determination of ablation rates and thermal damage zones

Er:YAG lasers are known to superficially ablate skin and other tissues with minimal thermal coagulation zones. The ablation efficacy and thus the clinical applicability of these lasers, however, was limited due to small beam diameters and repetition rates. Aim of this study was to determine the ablation efficacy and the amount of thermal damage with a new high‐power high‐repetition‐rate Er:YAG laser and to find optimal treatment parameters for skin ablation.

Q-switch laser and tattoo pigments: first results of the chemical and photophysical analysis of 41 compounds.

In the Western world, there are at least 20–30 million people with tattoos. Improved self‐image and social stigmatization are the main reasons for removing tattoos from skin. Q‐switched lasers are applied to destroy the tattoo compounds in the skin. The treatment of tattoos containing ink often gives excellent results, whereas the results of treatments for coloured tattoos are not predictable and usually are worse. The chemical structure and the absorption spectra of the tattoo pigments are usually unknown. However, the efficacy of the treatment by using light of different Q‐switched lasers (wavelengths 510, 532, 694, 755, 1064 nm) is correlated to both the chemical structure of the tattooed compounds yielding specific absorption spectra and the laser wavelength used.

Long-pulse dye laser for photodynamic therapy: investigations in vitro and in vivo.

Continuous wave lasers or incoherent lamps are used effectively for photodynamic therapy (PDT). As the mechanism of action of pulsed lasers in PDT is not known, we investigated the efficacy of PDT with 5‐aminolevulinic acid (ALA) using a long‐pulse (1.5 ms) tunable flashlamp‐pumped pulsed dye laser (LPDL) in vitro and in vivo.

Side-effects and complications of flashlamp-pumped pulsed dye laser therapy of port-wine stains. A prospective study.

The flashlamp‐pumped pulsed dye laser (FPDL) was the first laser system specifically developed for the treatment of cutaneous vascular lesions such as port‐wine stains (PWS), tckmgiectases and haemangiomas. Its theoretical advantages have been verified by numerous excellent clinical results

Both the flashlamp-pumped dye laser and the long-pulsed tunable dye laser can improve results in port-wine stain therapy

Background At present, laser therapy of port‐wine stains (PWS) using the flashlamp‐pumped dye laser (FPDL) at 450 µs is accepted as the optimal approach. A few years ago, a new long‐pulsed tunable dye laser (LPTDL, 1·5 ms) was introduced for the treatment of leg veins.

Comparison of the 308-nm excimer laser and a 308-nm excimer lamp with 311-nm narrowband ultraviolet B in the treatment of psoriasis

Background  Psoriasis is a chronic, genetically determined inflammatory disease, characterized by an immunomediated pathogenesis, which affects approximately 1–3% of the population. Various modalities have been used for psoriasis treatment, including ultraviolet (UV) radiation. Narrowband UVB (311 nm) phototherapy is a well‐established, widely used and highly efficient treatment for psoriasis, but a big disadvantage is that large areas of unaffected skin are irradiated along with the psoriatic lesions.

Mycophenolate mofetil and cyclosporin treatment for recalcitrant pyoderma gangrenosum

A 68-year-old woman with an uneventful medical history developed painful ulcers on both shins over a period of 6 months. She had large, inflamed, shallow, pretibial ulcers on both legs with a violaceous, partly bullous, and necrotic, undermined border. Diagnosis of pyoderma gangrenosum (PD) was confirmed by a biopsy specimen, which showed massive inflammatory-cell infiltration, thrombosis of dermal vessels, and leucocytoclastic vasculitis. Except for mild hyperthyroidism, no disease usually associated with PD was found. Treatment was begun with oral steroids (120 then 80 mg methylprednisolone per day) and clofazimine (200 mg/day). After 2 weeks, due to disease progression, cyclosporin was added (250 mg/day) but had to be discontinued as severe hypertension developed. Steroids were raised to 120 mg/day and cyclophosphamide therapy was started (500 mg intravenously on day 1, 50 mg by mouth on days 2–7). The lesions responded well at first, but recurrence developed after discontinuation of cyclophosphamide due to severe neutropenia. Over the next few months, the ulcers grew continuously despite treatment with high-dose intravenous immunoglobulins, dapsone, several cycles of high-dose intravenous steroids, and thalidomide 200 mg daily, each treatment having been given over several weeks. The ulcers now involved muscles and tendons of both shins. Reintroduction of cyclosporin (250 mg by mouth, this time tolerated with only mild hypertension) also had no effect. The patient was fed intravenously. The ulcers had to be debrided three times under general anaesthesia, requiring the excision of both Achilles tendons and parts of extensor muscles and tendons due to progressive necrosis. After 10 months of unsuccessful treatment, we decided to start mycophenolate mofetil (MM) 2 g/day by mouth in addition to cyclosporin and intravenous steroids. Autologous thrombocytic factors (platelet derived wound healing factors [PDWHF] Curative Technologies GmbH, Moers, Germany) were applied topically. After 14 days, the ulcers had stable borders. Healing continued until, 7 weeks after the introduction of MM, a split-thickness, meshed skin graft could be done. Healing was complete after another 4 weeks and has been now for a further 8 weeks without corticosteroids and with a reduced dose of 100 mg cyclosporin and 1 g/day MM, the latter tolerated without any side-effects. MM is effective in the prevention of renal transplant rejection. As a potent, non-competitive inhibitor of inosinmonophosphate-dehydrogenase, it influences the function of lymphocytes via the inhibition of purine synthesis. Its sideeffects are mostly restricted to mild gastrointestinal symptoms. Some evidence exists that it may also be effective in rheumatoid arthritis, psoriasis, and bullous pemphigoid. In our case, the first stable response after 10 months occurred after introduction of MM in addition to cyclosporin. Because cyclosporin monotherapy had been unsuccessful in this patient, we believe that the combination of MM and cyclosporin was the effective treatment, although application of PDWHF may have helped.

Recurrence of port-wine stains after treatment with the flashlamp-pumped pulsed dye laser.

Objectives To assess the importance of the patient’s age at the start of treatment of a port‐wine stain (PWS) with the flashlamp‐pumped pulsed dye laser (FPDL).

Role of Lasers and Photodynamic Therapy in the Treatment of Cutaneous Malignancy

Tumor therapy is not a common indication for the use of lasers, as it is in the treatment of benign vascular skin lesions, since many alternative treatment modalities exist. However, certain patients may benefit from laser therapy of premalignant and malignant skin tumors. Skin tumors can be treated by laser excision, laser coagulation, laser vaporization, or photodynamic therapy (PDT). For these purposes, the carbon dioxide laser, the neodymium:yttrium aluminum garnet laser and the argon laser are particularly suitable. PDT is a therapeutic approach based on the photosensitization of the target tissue by topical or systemic photosensitizers and subsequent irradiation with light from a laser or a lamp inducing cell death via generation of reactive oxygen species.Laser therapy and PDT have shown good results in the curative treatment of actinic keratoses, superficial basal cell carcinoma, Bowen’s disease and cheilitis actinica. However, they are not recommended for primary malignant melanoma and invasive squamous cell carcinoma. In some patients, lasers and PDT might also be used effectively for the palliative treatment of cutaneous metastases.In selected patients, lasers and PDT may offer some advantages over routine procedures, e.g. reduction of scarring and better cosmetic results. However, when treating invasive tumors with curative intention, one has to bear in mind the lack of histologic control and the limited depth of tissue penetration of most laser and PDT therapies.

Increase in telomerase activity during progression of melanocytic cells from melanocytic naevi to malignant melanomas

Abstract During successive cell divisions of mortal cells the length of the telomeres (TTAGGG repeats in vertebrates) at the end of chromosomes decreases. It has been suggested that this process is responsible for cellular senescence. Expression of the ribonucleoprotein telomerase appears to prevent shortening of telomeres in germ-line cells and cancer cells. The purpose of this study was to investigate telomerase activity in melanocytic lesions and its possible role in the multistep tumor progression model of malignant melanoma. To quantify the level of telomerase activity both in cultured cells and in fresh tissue samples the TRAP (telomeric repeat amplification protocol) ELISA was used. Eight cell lines of malignant melanoma, 3 primary cultures of fibroblasts, 36 melanocytic naevi, 5 atypical melanocytic naevi, 3 Spitz’s naevi, 31 primary malignant melanomas and 13 metastases of malignant melanomas were investigated. Also 34 samples of skin (22 samples of perilesional skin and 12 samples of normal skin) were analysed. In our experiments all melanoma cell lines were strongly positive, whereas in fibroblasts telomerase activity could not be detected. Of the primary melanomas and metastatic melanomas, 90.3% and 92.3%, respectively, were strongly positive, and of the atypical melanocytic naevi, 80% were positive. Of the 36 common melanocytic naevi only 10 (27.7%) expressed weak telomerase activity and of the 34 samples of human skin, 4 (11.7%) expressed very weak telomerase activity. Our results indicate that telomerase activity increases from benign melanocytic naevi to atypical naevi and further to malignant melanoma and metastatic melanoma cells, and therefore may play a role in tumour initiation and progression.