Rare ashy dermatosis‐like hyperpigmentation associated with osimertinib

Osimertinib, a third‐generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), is the most reliable EGFR‐TKI and is widely used as the first‐line treatment for EGFR mutation‐positive non‐small cell lung cancer. Pigmentary changes caused by EGFR‐TKIs are unusual, and to the best of my knowledge, hyperpigmentation with osimertinib has rarely been reported as a skin‐related adverse event. Here, I report a case of osimertinib‐associated ashy dermatosis‐like hyperpigmentation on imaging. Although reducing the dose of osimertinib to 40 mg did not improve pigmentation, osimertinib use was continued due to its clinical and radiological benefit, which persisted for a long time.