Toxicoderma Secondary to 5-Fluorouracil: Differential Diagnosis of Paraneoplastic Pemphigus

Abstract

We present the case of a patient undergoing chemotherapy with 5-Fluorouracil (5-FU), irinotecan and cetuximab, who presented polymorphous skin lesions with oral and genital mucosal involvement. The differential diagnosis included paraneoplastic pemphigus, a severe autoimmune disease associated with neoplasms. The histology can be variable with acantholysis or lichenoid dermatitis. The presence of circulating antibodies supports the diagnosis. In our case, the anatomopathological and immunological findings and the clinical improvement after the suspension of 5-FU confirmed that it was toxicoderma secondary to the latter.