Capecitabine-induced diffuse palmoplantar keratoderma: is it a sequential event of hand-foot syndrome?

Capecitabine was developed as a prodrug of 5-fluorouracil (FU), with the goal of improving tolerability and intratumour drug concentrations through tumour-specific conversion to the active drug against numerous types of neoplasms. The most frequent adverse cutaneous reaction associated with capecitabine is hand foot syndrome (HFS), presented with symmetrical erythema, dysaesthesia, and desquamation on the palms and soles. Acquired palmoplantar keratoderma (PPK) can occur in various dermatoses associated with metabolic abnormalities, malignancies, and toxic agents. However, there has been no report of PPK after capecitabine chemotherapy. We report two cases of diffuse PPK, which developed in patients with metastatic breast cancer after one cycle of capecitabine chemotherapy. Because oral capecitabine is increasingly used for various solid tumours, clinicians should be aware that keratoderma can develop during capecitabine chemotherapy as a sequential event of HFS.