CNS Involvement in Non-CNS Tumors

Abstract

This chapter describes the clinical neuroradiology of three broad areas of brain and intracranial involvement with systemic malignancy: metastases, lymphoproliferative disorders, and paraneoplastic syndromes. Intracranial metastases can be parenchymal, leptomeningeal, and dural. They most commonly arise from breast, lung, and colon cancer and melanoma. The lymphoproliferative disorders concern a range of parenchymal and meningeal disorders in hematological cancer, namely, leukemia, systemic lymphoma, and posttransplant lymphoproliferative disorder. Primary CNS lymphoma is outside the scope of this chapter and discussed elsewhere in this book. The paraneoplastic syndromes have as a common denominator an immune-mediated response to a primary malignancy remote from the CNS. Paraneoplastic syndromes of the brain include autoimmune (limbic) encephalitis (also known as limbic encephalitis), paraneoplastic rhombencephalitis, and cerebellar degeneration.

While in many cases a primary malignancy is known, the CNS findings may be the presenting symptom. Prompt and accurate radiological diagnosis is of utmost importance in these cases for a timely systemic assessment and start of anticancer treatment. An important consideration is that tissue diagnosis is severely hampered by corticosteroid use in patients with lymphoma, which should therefore be withheld in any suspicion of lymphoma to avoid misdiagnosis and delayed treatment of these patients.

Differential diagnosis of CNS involvement with systemic disease is not always straightforward and may include primary brain tumors, but may also be complicated by coexisting morbidity (such as immunodeficiency in hematological cancer) or treatment effects (such as neurotoxicity of chemo- and radiation therapy). Advanced radiological techniques, such as MR perfusion imaging, MR spectroscopy, and PET imaging, may be helpful in selected cases.

This publication is endorsed by: European Society of Neuroradiology (www.esnr.org).