Black Hairy Tongue After Immune Checkpoint Inhibitors in NSCLC: A Case Report and Review of the Literature

• Immune checkpoint inhibitors (ICIs) are associated with the development of unique immune-related adverse events (irAEs), which emerged primarily during post-marketing surveillance. Oral irAEs have already been reported, with the most common manifestations being mucositis and xerostomia. It has been suggested that a T-cell activation, similar to that observed in autoimmune conditions, may play a role. • Here, we report a case of black hairy tongue (BHT) in a patient receiving first-line pembrolizumab for advanced non–small-cell lung cancer (NSCLC). Although the BHT was symptomatic for burning mouth and dysgeusia, ICI use was continued due to its clinical and radiological benefit, which persisted for a long time. • BHT is characterized by hypertrophy and lengthening of the filiform papillae. Despite being a rare benign condition, it can often result in a significant burden on quality of life. • Many predisposing factors have been described, and cancer patients represent a population pa...