Neurolymphomatosis of the brachial plexus from atypical primary central nervous system lymphoma lesions: A case report and review of the literature.

Background: Primary central nervous system lymphoma (PCNSL) is an aggressive and extranodal non-Hodgkin lymphoma limited to the neuroaxis. In immunocompetent individuals, PCNSL is more common in older adults and lacks the association with the Epstein-Barr virus found in individuals with AIDS-associated PCNSL. Because the clinical presentation and radiographic findings of PCNSL are highly variable, stereotactic brain biopsy is typically required for definitive diagnosis. High-dose methotrexate, in combination with other chemotherapeutic agents with or without whole brain radiation, is the mainstay of treatment. Case Description: A 70-year-old HIV-negative woman presented with confusion, acute flaccid left arm weakness, and left hand numbness. Head computed tomography without contrast demonstrated a 1 cm hyperdense round lesion in the suprasellar cistern that prompted further evaluation. Gadolinium-enhanced brain magnetic resonance imaging demonstrated enhancing lesions with heterogeneous signal intensity in the suprasellar, pineal, and right periatrial regions that did not explain the limb weakness and numbness. Serum and cerebrospinal fluid (CSF) studies were unrevealing, and a diagnosis of PCNSL was made following stereotactic biopsy. The patient's liver cirrhosis precluded chemotherapy, but treatment with whole-brain radiation was pursued. Conclusion: The myriad clinical presentations and insidious course of PCNSL contribute to diagnostic difficulties, delays in treatment, and poor outcomes. Stereotactic brain biopsy is the primary method of PCNSL diagnosis since malignant cells are typically not detected in CSF. PCNSL should be considered in the differential diagnosis when immunocompetent elderly patients present with multiple intracranial lesions, even in the presence of lower motor neuron findings.