Trichomegaly of the Eyelashes After Treatment with Erlotinib in Non-Small Cell Lung Cancer

A 61-year-old female patient with advanced non-small cell lung cancer experienced trichomegaly (excessive eyelash growth) after being treated with the EGFR tyrosine kinase inhibitor erlotinib. She did not develop the typical skin rash associated with this class of drugs but did require trimming of her eyelashes due to overgrowth causing visual disturbance and corneal irritation. The patient's eyelashes became dark and coarse, while her scalp hair remained fine and brittle. This case contributes to the understanding of cutaneous side effects of EGFR inhibitors, which are thought to be linked to the inhibition of EGFR and are being investigated as potential clinical markers of drug response. The patient showed a marked symptomatic improvement in exercise tolerance and bronchial secretions with static disease on radiological imaging after 4 weeks of treatment, and she did not experience significant cutaneous or gastrointestinal toxicity during her 10 months of treatment. The case highlights the need for further research into EGFR tyrosine kinase binding domain mutations and the potential use of cutaneous toxicity as a clinical marker of response to EGFR inhibitors.