[Primary central nervous system lymphoma in immunocompetent patient: A case report].

Introduction: Primary central nervous system lymphoma (PCNSL) is an extranodal lymphoid neoplasm that affects the brain, spinal cord, leptomeninges or the vitreous-retina space, without systemic involvement. It represents 3% of CNS tumors predominantly in the context of immunosuppression (HIV infection, post-transplant). The clinical presentation and radiological findings are highly variable, representing a diagnostic challenge especially in immunocompetent patients. Its prognosis is unfavorable despite the high response to initial treatment. Clinical case: 69-year-old man, hospitalized for upper motor neuron syndrome and intracranial hypertension. No abnormal laboratory studies were found and a contrast-enhanced tomography of the head revealed multiple contrast-enhancing lesions with vasogenic edema. Extension studies in search of a primary tumor were negative. MRI demonstrated lesions with characteristics consistent with lymphoma. A PET/CT with 18-fluorodeoxyglucose was performed, which ruled out systemic involvement, and a brain biopsy confirmed PCNSL with histopathologic features of a diffuse large B cell lymphoma. The patient was sent to the hemato-oncology department at a third level hospital for chemotherapy, he completed two cycles of high-dose methotrexate plus rituximab without response and fatal outcome. Conclusions: PCNSL is an aggressive, low-incidence, extranodal lymphoma, which should be considered in immunocompetent patients over 60 years old with multiple brain lesions, in order to initiate treatment in a timely manner.