Primary CNS lymphoma mimicking demyelinating disease

Abstract

Case report: Male, 32-year-old, diagnosed with COVID-19 (coronavirus disease) in January 2022 and two weeks later present progressive vertigo, gait instability, binocular diplopia and right facial palsy. Three months later he was sent for investigation in our service. Magnetic resonance imaging (MRI) showed a FLAIR-hyperintense lesion in the pontomesencephalic transition with gadolinium enhancement. Cerebrospinal fluid (CSF) analysis shows increase in protein level (83 mg/dL). In this moment, considering the infectious antecedent and MRI characteristics, he has been diagnosed with acute disseminated encephalomyelitis (ADEM) and submitted to pulse therapy with methylprednisolone, showing complete improve of symptoms. In outpatient follow-up he presents with worsening of symptoms. Ten months after onset of symptoms he was hospitalized again, MRI showed new lesions on medulla and cerebellum. Submitted to pulse therapy followed by plasma exchange, with no improve. New MRI presents with infiltrative lesion without gadolinium enhancement. CSF analysis show 48 cells (98% lymphocytes), no evidence of neoplastic cells. A biopsy was performed on the lesion and showed atypical lymphoid infiltrate with B-Cells predominance, positive to CD20 and CD45, confirming diagnosis of Primary CNS Lymphoma (PCNSL). Initiated chemotherapy, but unfortunately patient die in consequence of neutropenia. Discussion: PCNSL is an uncommon neoplasm and rarely affects brainstem. When it occurs the prognosis is poor, nearly half of patients died within 1 year after diagnosis. Glucocorticoids could promote tumor shrinkage. Neuroimaging characteristics could be confounding with infections, demyelinating lesions, and gliomas. Conclusion: Our case illustrates a patient initially diagnosed with ADEM and submitted to corticotherapy with good response, however he worse in months later and the diagnosed reviewed to PCNSL. This shows the importance of considering atypical PCNSL in differential diagnosis of demyelinating diseases.