Eyelash trichomegaly complicating pembrolizumab for colorectal cancer.

IntroductionPembrolizumab is an immune checkpoint inhibitor widely administered for the treatment of various malignancies. Despite its effectiveness, its distinctive mechanism of action may lead to immune-related adverse events, most frequently affecting cutaneous tissues. Hair-related adverse events, although uncommon, include conditions such as alopecia areata and alterations in hair texture or type.Case reportA 63-year-old male patient presented with eyelash trichomegaly following two cycles of pembrolizumab infusion.Treatment and outcomeThe patient experienced discomfort due to the eyelash trichomegaly, prompting him to consider discontinuing the treatment. However, the patient's neoplastic disease demonstrated a complete radiologic response, which encouraged him to continue the therapy.DiscussionThis case illustrates a unique documentation of pembrolizumab-induced eyelash trichomegaly. While immune checkpoint inhibitors like pembrolizumab are known to cause hair-related adverse events, reports of eyelash trichomegaly remain rare. This case emphasizes the necessity for clinicians to remain vigilant about such uncommon side effects to ensure comprehensive patient management.