ABSTRACT
Chemotherapy, targeted therapies, and immunotherapy, regardless of the mechanism of action, can induce photosensitive eruptions. The most common cause of photosensitivity from cancer treatment is attributed to vemurafenib, with an incidence of more than 50% of patients. Photosensitivity is not a contraindication to continuing therapy if symptoms can be adequately controlled with supportive care and strict photoprotection. Photo-recall dermatitis is the reemergence of a prior phototoxic eruption provoked by administration of drugs. Chemotherapy, targeted therapies, and immunotherapy have all been reported to induce connective tissue diseases, such as subacute cutaneous lupus erythematosus, a photosensitive autoimmune condition. Pellagra, a photosensitive dermatitis caused by niacin deficiency, presents as an erythematous sunburn, followed by thickening of the skin, hyperpigmentation, and parchment paper–like scaling. The varied clinical presentations include exaggerated sunburn, photodistributed lichenoid eruption, subacute cutaneous lupus with elevated antinuclear antibody, photoinduced erythema multiforme lesions with positive photopatch testing, photodistributed blue-gray pigmentation, and photo-onycholysis.
