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.