Leptomeningeal Metastasis: A Rare Complication of Non-small Cell Lung Cancer.

Leptomeningeal metastasis (LMM) is a rare complication of non-small cell lung cancer (NSCLC) that can present with a range of neurological symptoms depending on the site(s) of metastatic involvement. We present a case of a 54-year-old woman who was initially diagnosed with suspected inflammatory neuritis secondary to a known systemic lupus erythematosus (SLE) diagnosis after presenting with multiple months of progressive neuro-ophthalmologic symptoms; however, she was eventually diagnosed with LMM secondary to a previously undiagnosed NSCLC. This case both underscores the challenges of diagnosing LMM due to its nonspecific presentation, as well as highlights the importance of including LMM in the differential diagnosis for patients presenting with vague neurological symptoms in the context of another inflammatory disease process.