Concurrent sarcoidosis and metastatic lung cancer in a patient with ring-enhancing brain lesions

This case discusses a male in his 40s with no prior medical history who presented to the emergency room with headaches and blurred vision and was found to have ring-enhancing lesions on brain MRI. Chest imaging revealed bilateral pulmonary nodules with a dominant right upper lobe nodule. On lung tissue sampling, he was found to have concurrent sarcoidosis and non-small cell lung cancer. Initial brain biopsy showed non-specific vascular lesions and inflammation which were initially thought secondary to sarcoidosis since there was no evidence of malignancy. However, given the importance of a definitive diagnosis to establish prognosis, repeat brain biopsy was pursued, which confirmed metastatic lung cancer. This case demonstrates the benefits of repeat biopsy in situations where clinical suspicion for malignancy is high, as well as the possibility for multiple concurrent diagnoses in a patient. The patient is currently undergoing stereotactic radiosurgery and chemotherapy with carboplatin, pemetrexed and pembrolizumab.