Why is My Skin Turning Black? A Rare Side Effect of Capecitabine

Abstract

Introduction: Capecitabine is an oral chemotherapy frequently used in the treatment of metastatic breast and colorectal cancers. Drug-induced cutaneous hyperpigmentation is a rare adverse effect of capecitabine, which is almost exclusively reported with development of hand-foot syndrome (HFS). Here, we report a case of capecitabine-induced hyperpigmentation affecting the hands, feet, face, and tongue in the complete absence of HFS.Case report: An 82-year old man presented with progressive hyperpigmentation of his hands, feet, face, and tongue shortly after initiating capecitabine for treatment of colon adenocarcinoma. There was no associated erythema, edema, blistering, desquamation, tingling, or tenderness. After completion of capecitabine therapy, he endorsed 95% resolution of all hyperpigmentation.Discussion: Previous reports of capecitabine-induced hyperpigmentation have argued that it may be a sign of impending toxicity and should be a part of the HFS grading scale. Others argue that the two are separate entities, yet the mechanism is still unknown. This case supports that capecitabine can cause hyperpigmentation independent of HFS, and thus, should be evaluated as a separate entity of HFS if other symptoms are lacking.