Case series: indoor-photosensitivity caused by fluorescent lamps in patients treated with vemurafenib for metastatic melanoma

Background: Vemurafenib, a selective inhibitor of genetically activated BRAF, is registered for unresectable stage III and stage IV melanomas harboring a BRAF mutation. Photosensitivity related to exposure to sunlight is a common side-effect. We here present three cases of indoor-photosensitivity due to fluorescent lamps, whilst undergoing treatment with vemurafenib. Case presentation: Patient A is a 45-year-old Caucasian female, patient B a 32-year-old Caucasian male and patient C a 53-year-old male. They are all undergoing treatment with vemurafenib for metastatic melanoma. Patient A developed indoor-photosensitivity due to fluorescent lamps at work. Her employer changed the lighting to LED light and her complaints disappeared. Patient B is a biology teacher and in classrooms he is exposed to fluorescent lamps. He developed alopecia and subsequently indoor-photosensitivity. This was solved by wearing a baseball cap at work during the day. Patient C developed red and burning skin after working under fluorescent lamps in his shed. This side-effect disappeared completely after avoiding the lamps. Conclusion: Photosensitivity is a known adverse event of vemurafenib. This is known to be an UVA-depended photosensitivity. Until now it was thought to be solely related to sunlight exposure. These cases illustrate that patients, whilst undergoing treatment with vemurafenib, can develop indoor-photosensitivity as a result of exposure to fluorescent lamps with a relatively high UV content of the emitted spectrum (low permissible exposure time). Awareness of this side-effect is important to take appropriate measures in the future.