Pembrolizumab-Induced Immune-Mediated Glossitis

Pembrolizumab (Keytruda), an anti-PD-1 antibody used in the treatment of several different malignancies has been identified to cause adverse effects pertaining to multiple body systems which include respiratory, gastrointestinal, dermatologic, and endocrine manifestations known as immune-related adverse events (IRAEs). Skin manifestations have been most described in current literature highlighting the most common adverse effects of this agent. However, adverse outcomes involving the oral mucosa have been rarely identified in the PD-1 and PD-L1 inhibitor classes of immunotherapeutic agents. We present a case of a 71-year-old male who was treated with a chemotherapeutic regimen including pembrolizumab for newly diagnosed squamous cell carcinoma of the lung, who later developed ulcerations on his tongue that were consistent with glossitis. Upon determining that this adverse effect may be immune-related, the patient was treated with oral prednisone 40 mg with a 10 mg taper each subsequent week, which resulted in significant improvement in the patient's symptoms following one month of treatment.