What happened, in summary

A 51-year-old woman developed difficulty using her right hand, trouble writing, imbalance, a shuffling gait, and mild headache. Brain MRI found a 2.7 cm left occipital mass and a smaller left frontal lesion. Chest CT showed a 2.7 cm mass in the lingula of the left upper lung. Biopsy confirmed very poorly differentiated lung adenocarcinoma. The tumor expressed PD-L1 at 100%, while next-generation sequencing found no actionable mutations. Staging was T1cN0M1b with two brain metastases. She underwent a left parietal craniotomy with complete removal of the occipital metastasis. Pembrolizumab was started, together with fractionated radiation to the surgical bed and stereotactic radiosurgery to the frontal lesion. After completing 11 cycles of pembrolizumab, she underwent robotic-assisted resection of the left upper lobe lingular segment and lymph nodes. Pathology showed only a 0.4 cm residual poorly differentiated adenocarcinoma and no involved lymph nodes, corresponding to ypT1aN0. The report described an excellent pathologic response. At the latest follow-up, she was no longer receiving pembrolizumab or radiation and remained under observation in remission.