Sarcoid-like reaction and hypothyroidism induced by PD-1 inhibitor treatment in metastatic renal cell carcinoma: a case report and literature review

Pembrolizumab is among the approved treatments for a variety of cancer types, including clear cell renal cell carcinoma (ccRCC). It has contributed to enhancing the prognosis of renal cell carcinoma. However, it is essential to be aware of the numerous potential immune-related side effects associated with its use. A 69-year-old patient with a history of metastatic renal cell carcinoma has been undergoing treatment with Pembrolizumab, an immune checkpoint inhibitor. The medication has led to the development of a sarcoid-like reaction, initially misinterpreted as cancer recurrence and progression. Additionally, the patient has experienced new-onset hypothyroidism, which has been attributed to the immunotherapy. Clinicians, including oncologists, endocrinologists, and radiologists, should maintain a high level of suspicions and awareness regarding the potential adverse events associated with newly introduced immunotherapies like pembrolizumab. This knowledge is crucial for the accurate diagnosis and appropriate management of patients receiving these treatments.