Because of the low incidence of primary central nervous system lymphoma (PCNSL) in non-HIV individuals and because of the lack of specific clinical manifestations and auxiliary examinations, the disease is easily missed or misdiagnosed.
Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma (NHL). The disease has an annual incidence of 0.46 / 100,000 and accounts for 1-2% of all cases of NHL  and 1-3% of all central nervous system (CNS) tumors. Compromised immune status is the only known risk factor for PCNSL, and the incidence of PCNSL is high in HIV-positive populations.
PCNSL In Patients
The causes of PCNSL in patients with normal immune function are still unknown. Because the incidence of PCNSL is much lower in individuals with healthy immune functions compared to the HIV-positive population, there is a lack of large-scale studies. Due to the short course of the disease and rapid progression, early diagnosis of PCNSL is essential. Because of the low incidence of PCNSL among non-HIV populations and because of the lack of specific clinical manifestations and auxiliary examinations, the disease is easily missed or misdiagnosed.
A better understanding of the imaging characteristics of PCNSL is critical to improving early diagnosis and treatment, and thus the prognosis of the disease. Therefore, the present study aimed at analyzing the imaging features of PCNSL in non-HIV patients. Out of the 118 patients, 73 (61.9%) were male, and 45 (38.1%) were female. Median age was 54 (range 11-83) years. All patients had B cell lymphoma.
The lesions showed slightly hyperintense shadows on computed tomography (CT) images, and mostly hyperintense T1 and iso-or hyperintense T2 signals on magnetic resonance imaging (MRI). Most lesions showed patchy enhancement after enhanced scanning, and some had the characteristic "butterfly sign" on enhanced MRI. The magnetic resonance spectroscopy of PCNSL manifested as increased Cho peak, moderately decreased NA peak, and slightly decreased Cr peak. Positron emission computed tomography indicated high metabolism of 18F-FDG in PCNSL lesions.
Patient data including gender, age, diagnosis and symptoms, clinical symptoms and signs, imaging data of the tumor (including magnetic resonance imaging (MRI), computed tomography (CT), and positron emission computed tomography (PET / CT)) , and pathological examinations were collected from the medical charts. MRI is essential in the diagnosis of PCNSL. Understanding the imaging features of PCNSL will help improve its diagnosis in clinics.