Case Presentation: A 65-year-old immunocompetent male with a history of ischemic stroke and new onset simple partial seizures presented with 4-weeks of worsening diplopia, vertigo, ataxia, nausea, and vomiting. The patient underwent magnetic resonance imaging (MRI) 2-months prior to admission that was unremarkable.
On admission, vital signs were stable. Physical exam demonstrated rightward horizontal nystagmus, 20/40 visual acuity bilaterally, and subtle bilateral dysmetria on finger to nose test. A complete neurologic exam was otherwise normal. Labs were unremarkable. An MRI showed a 1.7 x 2.5 x 1.8 cm homogenously enhancing mass that extended from the roof of the 4th ventricle. The patient had a posterior fossa craniotomy with stereotactic biopsy. Relevant immunostaining was positive for CD20, CD45, CD79a, MUM-1, MIB-1, BCL-6, and BCL-2. The final histopathologic diagnosis was Diffuse Large B-cell Lymphoma (DLBCL). Positron Emission Tomography (PET) imaging reported increased uptake in the 4th ventricular mass as well as a small focus of uptake in the right pituitary. Staging workup with Computed Tomography (CT) of the chest, abdomen, and pelvis, as well as whole body PET scan was otherwise negative for metastatic disease.
The patient was initiated on rituximab, intrathecal methotrexate, and a combination of systemic cyclophosphamide, vincristine, doxorubicin, and dexamethasone (hyperCVAD). Shortly after completing cycle 1 of his hyper-CVAD regimen, he was admitted for left sided weakness and encephalopathy. Repeat imaging demonstrated significant interval resolution of the CNS lymphoma, but identified an area of suspected ischemia in the right parietal lobe. The patient’s EEG demonstrated a right temporo-parieto-occipital epileptiform lesion with recurrent epileptiform discharges, thought to be a complication secondary to his DLBCL. His lumbar puncture was unremarkable. He was started on levetiracetam and lacosamide. His symptoms resolved with seizure control and initiation of whole brain radiation therapy.
Discussion: Primary Central Nervous Syndrome Lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin’s lymphoma that may originate in the brain, leptomeninges, spinal cord, or eyes. PSCNSL occurring in the ventricular system seldom occurs, with 16 known cases documented in the literature.
Literature review of the now 17 reported cases indicate all patients were immunocompetent and presented with variable clinical symptoms, including headaches, ataxia, diplopia, nausea/vomiting, confusion, cranial nerve palsies, seizures, and urinary incontinence. Clinicians should consider PCNSL on the differential in any adult patient presenting with a 4th ventricular mass. Magnetic resonance imaging will typically demonstrate isodense to hyperintense enhancement on T2-weighted imaging, with homogenous enhancement on post-contrast imaging. Treatment options are limited to phase 2 clinical trials, and while surgical and intrathecal chemotherapy are controversial options, they have been utilized in this patient cohort.
Conclusions: PCNSL involving the intracranial ventricular system is an uncommon occurrence with variable clinical manifestations. It primarily occurs in immunocompetent males and should be considered in any immunocompetent patient presenting with a posterior fossa mass. Currently, no standardized treatment protocol exists. Overall disease management remains a neuro-oncologic challenge, and survival is inferior to other extranodal manifestations of NHL.