Don't Miss Hidden Spread in Lung Cancer: Recognizing Leptomeningeal Metastasis
Summary: Dr. Shuang LI of Shanghai GoBroad Cancer Hospital, China Pharmaceutical University, shares key points on recognizing and managing leptomeningeal metastasis (LM) from lung cancer. Because symptoms can be subtle and conventional imaging may miss the disease, specialized MRI sequences such as black-blood imaging, together with cerebrospinal fluid (CSF) cytology, can be important for diagnosis. The hospital has established a multidisciplinary LM team and an integrated pathway covering black-blood MRI, CSF sample management, standardized neurologic assessment, and intrathecal therapy, providing coordinated care for patients with advanced lung cancer involving the central nervous system.
In recent years, the wider use of targeted therapies and other newer treatments has helped many patients with advanced lung cancer live longer. Most people are familiar with “brain metastases,” which usually refers to tumors that have spread into the brain tissue itself. As survival has improved, leptomeningeal metastasis is also being detected more often.
What exactly is leptomeningeal metastasis? In simple terms, it means that cancer cells have spread to the thin membranes surrounding the brain and spinal cord - the leptomeninges - and into the subarachnoid space. Some patients may have no visible metastases within the brain tissue itself, yet large numbers of tumor cells can still be found in the cerebrospinal fluid. These cells may attach to and cluster along the surface of the spinal cord, leading to a range of neurologic symptoms.
Subtle Symptoms, Potentially Serious Consequences
Leptomeningeal metastasis can develop quietly and may be easy to miss. Possible symptoms include:
Signs of increased intracranial pressure: persistent nausea, headache, or vomiting.
Neurologic symptoms: these vary depending on which nerves or areas of the nervous system are affected.
Cranial nerve involvement may cause difficulty swallowing or blurred vision.
Involvement of the cauda equina may lead to problems such as loss of bladder or bowel control.
Why Can Routine Tests Miss It?
This is one of the main diagnostic challenges. Conventional CT and routine MRI may not always show leptomeningeal disease clearly. Some patients need specialized MRI sequences to reveal signs of meningeal involvement. The images below illustrate the difference in one case:
Conventional contrast-enhanced MRI mainly shows enhancement of blood vessels within the brain tissue and may not clearly distinguish whether leptomeningeal metastasis is present.
On a specialized black-blood MRI sequence, the meninges show clear thickening and enhancement, raising suspicion for leptomeningeal metastasis. This illustrates why specialized MRI sequences can be important when LM is suspected.
Case Example: Lung Adenocarcinoma With Leptomeningeal Metastasis
In November 2025, the patient was admitted after a sudden episode of impaired consciousness. A conventional CT scan showed no acute intracranial hemorrhage, cerebral infarction, or obvious space-occupying lesion. During a diagnostic lumbar puncture, the cerebrospinal fluid pressure measured 300 mmH2O, above the usual reference range of approximately 80-180 mmH2O. CSF cytology detected malignant cells, and together with the clinical findings, this supported a diagnosis of leptomeningeal metastasis. During the course of the illness, the patient had experienced headache, nausea, and vomiting, followed by impaired consciousness as the condition progressed.
At follow-up in January 2026, the patient's symptoms had improved significantly. Repeat CSF testing showed that pressure and protein levels had returned to the reference range, and no malignant cells were detected on cytology. Black-blood MRI also showed resolution of the previously abnormal enhancement along the cerebral sulci and gyri, indicating radiographic improvement of the meningeal involvement.
To address common challenges in the diagnosis and treatment of leptomeningeal metastasis from lung cancer, our hospital has established a dedicated LM multidisciplinary team (LM-MDT), bringing together specialists from radiology, laboratory medicine, oncology, ultrasound, and other disciplines. The team has developed an integrated care pathway covering black-blood MRI, standardized CSF sample management, neurologic assessment, and intrathecal drug administration, while also conducting exploratory clinical studies aimed at improving diagnostic and treatment standards. Through this multidisciplinary model, the team seeks to provide coordinated, full-course care for patients with advanced lung cancer and central nervous system metastases.