Abstract
Immunotherapies have reduced reliance on cytotoxic strategies with their associated high toxicity levels, revolutionizing cancer care. However, these targeted therapies have also increased prevalence of previously rare sequelae, impacting patients experiencing longer survival. We describe a case of endometrial adenocarcinoma with lung metastases, in which tumor resolution following immunotherapy created cystic airspaces, leading to a pneumothorax complication. A 49-year-old female with advanced stage endometrial adenocarcinoma and lung metastasis developed cystic lung lesions in areas of previous metastatic lesions after treatment with Pembrolizumab and Bevacizumab. She developed a pneumothorax secondary to the rupture of one of the large lung cysts, leading to a bronchopleural fistula and required surgical intervention. Structural lung changes, such as cystic lung disease following immunotherapy are emerging complications. As immunotherapy continues to reshape cancer treatment, the emergence of associated complications highlights the need for optimized screening and management strategies for these newly recognized manifestations of cancer therapy.