Background  In the past, primary central nervous system lymphoma (PCNSL) patients with immunodeficiency have been the most common. However, in recent years, PCNSL cases with normal immune function are increasing, and the age of onset shows a younger trend. The study of the characteristics of patients with normal immune function of central nervous system lymphoma is helpful to improve the understanding of primary central nervous system lymphoma and improve the rate of early diagnosis.

  Objective  To analyze the clinical and imaging features of PCNSL, and provide evidence for clinical diagnosis.

  Methods  A total of 51 cases of primary intracranial lymphoma confirmed by pathology in the First Medical Center of Chinese PLA General Hospital from January 2001 to September 2019 were collected, and their clinical and imaging features were analyzed retrospectively.

  Results  Of the 51 cases, there were 31 males and 20 females, with a male-to-female ratio of 1.6 to 1. The average age of onset was (53.5 ± 11.6) years. About 35.3% of the patients had acute onset, and the proportion of patients with non-specific symptoms such as headache (51.0%), dizziness and fatigue (33.3%) was high, and the initial misdiagnosis rate was 29.4%. With the progress of the disease, the proportion of patients with motor dysfunction, cognitive dysfunction and eye involvement increased significantly. Most of the lesions were in frontal lobe (51%) and temporal lobe (39.2%). Moderate and severe edema showed in 70.6% of patients, and 62.5% of patients had moderate and severe space occupying effect. Multiple lesions were more common (72.5%). The frontal lobe involvement of multiple lesions group (62.2%) was significantly higher than that of single focus group (21.4%). CT imaging showed high density in 47.8% of the patients, T1WI showed low signal in 82.9% of patients, T2WI showed high signal in 78% of the patients, DWI showed high signal in 71% of the patients, and uniform enhancement in 52.6%.

  Conclusion  PCNSL is more common in middle-aged men, with headache, dizziness and fatigue as common onset symptom. With the aggravation of the disease, the proportion of motor system, cognitive function and eye involvement increase significantly. MRI show that multiple lesions are more common, mostly in the frontal lobe, with high signal intensity on DWI, low signal intensity and enhancement on T1WI, most of which are accompanied by edema and space occupying effect in different degrees. The misdiagnosis rate of early diagnosis is high. Clinicians should skillfully master the clinical and imaging features of PCNSL in order to improve the accuracy of early diagnosis.