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Leptomeningeal Melanoma

Leptomeningeal Melanoma

Question

Dear OncoLink "Ask The Experts,"

What is leptomeningeal melanoma? What medication can help?

Answer

Keith T. Flaherty, MD, Assistant Professor of Medicine (Hematology/Oncology), responds:

Leptomeningeal melanoma refers to the spread of melanoma cells to the tissue that lines the outside of the brain and spinal cord. It generally occurs in the setting of melanoma that has spread to other parts of the body as well. However, there are reported cases of melanoma cells appearing in this location as the first and only site of metastatic spread.

If there is no history of primary melanoma, then two other conditions must be considered in a young person: meningeal melanocytoma and neurocutaneous melanosis. The former can be a benign condition, while the latter is generally more life-threatening.

The brief description of this case sounds more consistent with a malignant and life-threatening condition based on the severity of the symptoms. Having said that, the final diagnosis is ultimately made by microscopic examination of cells recovered from the cerebrospinal fluid.

The treatment of leptomeningeal melanoma is very difficult. Temozolomide is the one systemic therapy that has an ability to cross the barrier separating the blood stream from the cerebrospinal fluid (known as the blood-brain barrier), and for which there is extensive experience in the treatment of melanoma. Radiation therapy can be directed at a portion of the involved leptomeninges, but not all, as radiation of the brain and spine at the same time is generally not tolerable in adults. Despite their limitations, both of these treatments are considered standard for this condition.