A Remarkable Clinical Response to Pembrolizumab in a Rare Spindle Cell Carcinoma of the Lung

Spindle cell carcinoma of the lung consists of only spindle-shaped tumor cells, and accounts for approximately 13.3% of all sarcomatoid carcinomas (SCs), which are a rare subtype of poorly differentiated non-small cell lung cancer (NSCLC). Spindle cell carcinoma of the lung has very poor prognosis owing to resistance to chemotherapy and radiotherapy. This case report describes a 76-year-old man who presented with complaints of dry cough and right-sided neck pain and was later diagnosed with spindle cell carcinoma of the lung. He had a medical history of type 2 diabetes, angina pectoris, atrial fibrillation, hypertension, hyperlipidemia, and hepatitis B and a 20 pack-year history of smoking. A computed tomography (CT) scan revealed a mass with a thick-walled cavity in the right upper lobe of the lung. His neck pain was consistent with PET-CT images, indicating metastases due to invasion of lung cancer cells. The expression of PD-L1 in more than 90% of the tumor cells of the lung biopsy tissue led to the administration of pembrolizumab. The lung and metastatic tumors dramatically decreased in size after 9 weeks, and no tumor regrowth was observed over 11 courses of pembrolizumab administration. To the best of our knowledge, there are no previous reports describing the use of pembrolizumab for spindle cell carcinoma of the lung. This case report suggests that immunotherapy could be a promising treatment option for rare types of lung cancers, including spindle cell carcinoma.