Gefitinib-associated lichen planus pigmentosus-like eruption.

The epidermal growth factor receptor (EGFR) signaling pathway is one of the oncogenic pathways in non-small cell lung cancer. Gefitinib is classified as a first-generation EGFR-tyrosine kinase inhibitor (TKI). A variety of cutaneous adverse effects related to the drug has been reported. Cutaneous hyperpigmentation is a rare side effect of EGFR inhibitor (EGFRi). Herein, we report a 62-year-old woman with non-small cell lung carcinoma who presented with symmetrical, slate-gray-to-brownish-black macular pigmentation on sun-exposed and non-sun-exposed areas after eight months of gefitinib administration. The clinical features were consistent with lichen planus pigmentosus. This case highlights the unusual hyperpigmented condition occurring in patients taking EGFR-TKIs.