Background: Primary central nervous system lymphoma (PCNSL) is a neoplastic entity associated with B symptoms. Note that the prevalence of intramedullary presentation is 0.02% of reported cases. Aim: This study was designed to show the oddity of PCNSL and illustrate the histopathological and magnetic resonance imaging (MRI) characteristics of this disease entity. Material and Methods: We obtained the histopathological diagnosis through stereotactic biopsy, and all lesions were resected at the Department of Neurosurgery, Centro Medico Nacional 20 de Noviembre. Results: We identified and included six lymphoma cases in a 5-year period: none of the patients had human immunodeficiency virus (HIV) infection; none were Epstein–Barr virus (EVB)-positive; all of them received chemotherapy and radiotherapy; and the survival rate was ≥1 year. Conclusion: Regarding the clinical data, the symptoms entirely depended on the location of the lesions. If the symptoms suggest malignancy, such as fever, weight loss, and night sweats, we searched for causes, other than the usual ones, to find a diagnosis. This is a rare disease, which responds well to medical treatment and has a survival greater than 5 years in some cases.