Osimertinib‑induced Erythromelalgia: A Case Report

The present study reports a case of osimertinib-induced erythromelalgia in a patient with metastatic lung adenocarcinoma. Osimertinib is an antineoplastic drug that irreversibly inhibits the epidermal growth factor receptor (EGFR) pathway by binding to the intracellular receptor tyrosine kinase site, thus preventing EGFR signal transduction. A 77-year-old female with a lung adenocarcinoma recurrence with secondary metastases was prescribed osimertinib therapy. The patient presented with painful erythema and warmth in the distal phalanges of all fingers on both hands, which worsened with heat and relieved with cold. Based on clinical data, erythromelalgia was diagnosed. Considering the age of onset, a primary erythromelalgia was ruled out. Further investigations excluded other secondary causes of erythromelalgia, therefore osimertinib was suspected as the cause. Although no cases of EGFR inhibitor-induced erythromelalgia have been reported, cutaneous adverse events induced by EGFR inhibitors have been documented. The present case may be the first evidence of osimertinib-induced erythromelalgia and may help clinicians to properly support patients who develop this EGFR inhibitor adverse event.