4. Discussion
The clinical presentation of BNS as shown in this case is diverse and non-specific. A critical point that could explain the under recognition of BNS is its frequent occurrence independent of any systemic progression of WM, with up to one-third of BNS cases coinciding with diagnosis of WM [2, 3]. Radiological assessment was critical to the diagnosis in this case requiring input from experienced neuroradiologists. In a case series of 24 patients the most common MRI finding was leptomeningeal infiltration either intracranial or spinal with a prevalence reaching 70.8% [4]. Dural and parenchymal involvement were present in 37.5% and 41.7% of patients, respectively. Autopsy results have observed more extensive meningeal and perivascular infiltration by malignant cells than that revealed by MRI [5]. the gold standard for diagnosis is a histological biopsy of the affected area or CSF analysis by flow cytometry demonstrating malignant cells as previously outlined [1].
There is no established treatment regimen for BNS to date. Patients typically receive a combination of systemic and IT chemotherapy, immunotherapy, and novel agents, such as ibrutintib, an oral Bruton kinase inhibitor. The goal of treatment should be to (1) reverse the patient’s clinical symptoms and (2) induce prolonged progression-free survival [6]. Remission has been reported with both IT therapies and/or systemic chemotherapies [1, 2, 7, 8]. Use of high-dose MTX is extrapolated from data in primary CNS lymphoma while direct evidence supports the use of Rituximab in BNS [3, 9]. Ibrutinib, has been increasingly employed in BNS treatment, as well as other primary CNS lymphomas [10-12]. Data suggests ibrutinib maintenance also has a role in prolonging progression-free survival rationalising its use in our patient’s case [13]. In one review of 34 patients with BNS, the estimated overall survival rate at 3 years was 59% [14]. Age > 65 years, thrombocytopenia and previous treatment for WM were all associated with worse prognosis [14]. Our patient has none of these characteristics and remains in complete remission 6 months post diagnosis.