Primary central nervous system lymphoma (PCNSL) may be hardly distinguishable both clinically and radiologically from some white matter diseases, such as Behçet’s syndrome, multiple sclerosis, demyelinating or inflammatory disorders. Misdiagnosis of these cases leads to delay the accurate treatment of PCNSL that is one of the most malignant tumors. This report describes a rarely detected case of PCNSL mimicking a neuro-Behçet disease in young patient. The patient’s MRI and clinic onset as same as his familial history (his father was diagnosed as Behçet disease, depression and died at an early age of 51) lead to misdiagnose PCNLS as Behçet disease. No improvement was noticed after his prescribed medical treatment. This led his doctors to decide performing new MRI. Repeated MRIs showed progression of the initial lesions. The neurosurgical team decided to perform biopsy under stereotactic guidance. Histopathological examination demonstrated that the lesion was diffuse large B-cell lymphoma. Herein, the neurosurgical team points out the importance of the stereotactic biopsy to distinguish PCNSL from other white matter diseases as well as to avoid the complications that may result from open craniotomy surgery in such deep located lesions.

Keywords: Large B-cell lymphoma, Behçet disease, stereotactic biopsy