RESUMEN
Background: Primary mediastinal B-cell lymphoma (PMBCL) is a subtype of diffuse large B-cell lymphoma that originates from a B cell in the thymus. It usually affects young female. Case description: A 30-year-old woman presented with mediastinal mass with history of shortness of breath and chest pain. blood analysis showed low levels of hemoglobin, hematocrit, and mean corpuscular volume and high red cell distribution width. A computed tomography (CT)-guided mediastinal core biopsy disclosed primary mediastinal large B-cell lymphoma (PMLBL) with a nongerminal center phenotype and lung tissue infiltrate. Moreover, after undergoing six cycles of rituximab, cyclophosphamide, hydroxydaunomycin, Oncovin, and prednisone (R-CHOP) chemotherapy and mediastinal radiotherapy, the patient presented with headache and visual disturbance due to multiple supratentorial lesions. Conclusion: Till date, only a few cases of central nervous system (CNS) metastasis have been reported in the literature. Moreover, CNS metastasis of refractory PMBCL is an uncommon event with a poor prognosis. Brain metastases are often the ultimate fatal consequence of many aggressive cancers, so early detection and treatment are important.