A rare case of miliary tuberculosis in a patient with NSCLC receiving PD1 inhibitor therapy, mimicking autoimmune pneumonitis

Abstract

Immune checkpoint inhibitors (ICIs) are widely used for the treatment of various types of cancer. One of the possible immune-related adverse effects of ICI is pneumonitis, which is a life-threatening condition that can present as a variety of radiographic patterns, so it can be difficult to differentiate from infectious cases of pneumonia based on radiological findings alone. We present a rare case of miliary tuberculosis (M. tuberculosis) in a patient receiving programmed death-1 (PD-1) inhibitor therapy mimicking autoimmune pneumonitis and possible pathophysiological mechanisms of this unexpected event. We presented a 52-year-old patient with stage IV non-small-cell lung carcinoma (NSCLC) who was admitted to the hospital with radiological and clinical signs of pneumonitis caused by immunotherapy-Pembrolizumab. During hospitalization, she was clinically, laboratory, and microbiologically processed and her diagnosis of M. tuberculosis was confirmed. Initial treatment started with corticosteroids as a pneumonitis treatment, and because there was no adequate response, and the diagnosis of tuberculosis was confirmed, treatment with a four-regimen antituberculotic drug started. On a control, CT scan regression in distribution and number of changes in lungs occurred. After a while, patient died due to hepatic failure. There are not many reported cases of pulmonary tuberculosis in patients receiving immunotherapy; to our knowledge, no cases of M. tuberculosis in a patient with lung cancer were described. Since there is a different approach to the treatment of tuberculosis and pneumonitis, we presented our dilemmas and literature review in this article. A multidisciplinary approach (oncologist, radiologist, microbiologist, etc.) is essential in a case like this.