Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 4, 2018
Primary Leptomeningeal Lymphoma
- Background
- Leptomeningeal, seeding from lymphoma, occurs as dissemination of a primary central nervous system lymphoma (PCNSL), or in 6-8% of patients with systemic non-Hodgkin lymphoma. In both cases, diffuse large B-cell lymphoma is the most frequent subtype;
- Primary leptomeningeal lymphoma (PLML) without parenchymal or systemic disease accounts for 7% of all PCNSLs.
- Clinical Presentation
- Symptoms and signs are referable to multiple levels of the central nervous system. The most common are cranial nerve palsies (predominantly abducens and facial nerve), and lumbosacral radiculopathies;
- Less frequent symptoms include headache, ataxia, and encephalopathy.
- Key Diagnostic Features
- MRI findings usually consist of leptomeningeal enhancement in T1WI, being the most common sites of the spinal cord and nerve roots;
- CSF studies are always abnormal (elevated opening pressure, leukocytosis, elevated protein concentration, and hypoglycorrhachia);
- Definitive diagnosis can be made by detection of malignant lymphocytes on cytology or flow cytometry. However, serial lumbar punctures may be required as sensitivity is dependent on the proportion of malignant cells in the obtained sample. If diagnosis is still not possible, a leptomeningeal biopsy may be required.
- Differential Diagnosis
- Carcinomatous meningitis/drop metastases: difficult to differentiate imagenologically PLML from these two entities. Primary tumor defines the diagnosis. CSF cytology may help to disclose diagnosis;
- Infectious leptomeningitis: clinical presentation and CSF findings may orientate the causative agent;
- Granulomatous meningitis: similar imaging findings after gadolinium administration, but usually low signal on T2WI.
- Treatment
- Radiation, systemic chemotherapy or CSF-directed chemotherapy are usually administered separately or combined;
- Between 50-70% percent of patients achieved a complete clinical, CSF, and radiographic response after a first treatment course, although relapses are frequently observed.
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