A rare case of late-onset lichenoid photodermatitis after vandetanib therapy

INTRODUCTION Vandetanib (ZD6474, Zactima) is a novel inhibitor of multiple tyrosine kinases that has been used for the treatment of various malignancies including medullary thyroid carcinoma. The drug functions primarily via inhibitory effects on vascular endothelial growth factor receptors, epidermal growth factor receptors, and the RET-tyrosine kinase system. As with other targeted chemotherapy agents, several cutaneous side effects including folliculitis, palmar-plantar hyperkeratosis, desquamation, cutaneous hyperpigmentation, and photosensitization have been reported. Photosensitivity, although less commonly reported, was found to make up 37% of cutaneous adverse effects in one case series. Most of these patients were found to exhibit a sunburnlike erythema in sun-exposed regions with subsequent desquamation. However, a small subset of patients exhibited a phenotypically lichenoid photodermatitis and a lymphocytic interface dermatitis with basal vacuolization and keratinocyte apoptosis upon histopathology. Only a handful of cases describing similar lichenoid eruptions after vandetanib use have been reported, most of which developed within a few weeks after exposure. We present a patient with a late-onset lichenoid photodermatitis that began 5months after initiation of vandetanib therapy.