Multiple basal cell carcinomas arising in radiotherapy-treated nevus flammeus: early detection facilitated by 595-nm pulsed dye laser

ARTICLE

Auteur(s) : Kjell M Kaune, Ellen Haas, Timo Buhl, Michael P Schön, Markus Zutt

Department of Dermatology, Venereology and Allergology, Georg August University, von-Siebold-Str. 3, 37075 Göttingen, Germany

The occurrence of basal cell carcinomas following radiotherapy for nevi flammei has been described in a few cases [1-3]. Because basal cell carcinoma (BCC) can infiltrate deeper structures, including muscles or bones, early detection of these tumors is essential. Problems may arise when BBCs are situated within nevi flammei and, obscured by the vascular malformation, often difficult to recognize.

A 46-year-old woman presented with a large unilateral congenital nevus flammeus extending over her right breast and parts of her thorax (figures 1A, B). About 40 years previously, the nevus flammeus was unsuccessfully treated by kilovoltage X-ray surface irradiation. Within the past 8 years, 14 BCCs (figure 1C) had developed within the nevus flammeus. Given that the nevus flammeus featured an inhomogeneous purplish color and somewhat uneven surface, the identification of BCCs arising within the vascular malformation proved very difficult. Upon clinical detection, BCCs were treated by surgical excision, cryotherapy or carbon dioxide (CO₂) laser ablation. In order to facilitate an early detection of BCCs and prevent a possible vascular proliferation, we treated the nevus flammeus of our patient using a pulsed dye laser (wavelength 595-nm; VBeam Pulsed Dye Laser, Candela Corporation, Boston, MA). We used a spot size of 7 mm, density energy up to 9 J/cm², and pulse duration of 3 ms. The expected purple-black purpura immediately after therapy (figure 1D) resolved within 2 to 3 weeks. Five treatments of the right breast and right half of the chest resulted in a marked alleviation of the nevus flammeus (figures 1E, F). Because this improvement is still lasting, the surface area is easy to follow up and an early detection of BCC is now possible (figures 1E, F).

Nevi flammei are benign vascular malformations consisting of superficial and deep dilated capillaries in the skin. After many years, the vessels can become ectatic, resulting in nodular structures, a complication that can be prevented by early therapy. The development of BCC within nevi flammei is uncommon. About 25 cases have been documented in the literature so far, mostly in association with prior radiotherapy, as seen in our patient [1-3]. The exact mechanism that leads to the development of BCC within irradiated nevi flammei is unclear. It has been suggested that the ectatic vessels produce an oncogenic factor, which might enhance the epidermal susceptibility to radiation [3]. Thus, patients suffering from nevi flammei who have a history of radiation exposure should be examined on a regular basis for BCCs. However, a clefted, verrucous or nodular surface, along with inhomogeneous coloration, which is often present in older nevi flammei, can make it very difficult to identify skin tumors. Laser treatment is a well-established therapeutic option used to improve nevi flammei. Whereas earlier treatments with non-selective lasers led to scarring, today's selective photothermolysis by pulsed dye laser has become the gold standard for treatment of nevi flammei. Their selective absorption of oxyhemoglobin, with relatively low melanin absorption, results in a good clearance rate of dermal capillary vessels. Most patients benefit from therapy with the conventional 585-nm laser. However, some lesions do not respond sufficiently [4]. We used the pulsed dye laser emitting light of the wavelength of 595 nm. Compared to the 585-nm pulsed dye laser, the slightly longer wavelength of 595 nm leads to deeper penetration into the skin, presumably resulting in additional coagulation of deeper vessels [5, 6].

In summary, we recommend short-term follow-up intervals for patients suffering from irradiated nevi flammei. Therapy with the 595-nm pulsed dye laser results in a good alleviation of symptoms and facilitates early detection of BCC.

Acknowledgements

References

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