Characteristics of SCNSL patients at initial systemic disease diagnosis:
Clinical findings are shown in Table 1. Half of the SCNSL patients (n=13) were older than 60 years old when diagnosed with systematic aggressive B cell lymphoma. Extranodal involvement was observed in 14 (53.8%) patients, breast involvement in 15.4% (n=4), testicular involvement in 11.5% (n=3), and involvement of the intestines, parotid gland, oral cavity, rhino, orbit and spleen in 26.9% (n=7). The histological findings were DLBCL in 92.3% (n=24) of the patients, mantle-cell lymphoma in 3.5% (n=1), and follicular lymphoma in 3.5% (n=1). For the initial treatment, 42.3% (n=11) of the patients used Rituximab-containing therapy. Only 7.7% (n=2) of the patients received intravenous HD-MTX for CNS prophylaxis.
Clinical and physiological findings, relapse site, pathological findings, and treatment at CNS relapse.:
All patients presented with brain parenchymal lesions, and one patient also had spinal cord compression. The symptoms of CNS relapse varied with location; the most common symptom was headache, and no epilepsy was observed in our study. Eye symptoms, such as blurred vision, were observed in 26.9% (n=7) of the patients. The time from clinical presentation to a definite diagnosis ranged from 4 to 180 days (median 30 days). One patient died of post-operation intracranial hemorrhage. Three patients presented to our center initially as PCNSL but were later detected as having systemic disease and were distributed to SCNSL.
In this study, 80.8% (n=21) of the patients were categorized as having isolated CNS relapse, 19.2% (n=6) had concurrent CNS and systematic disease, and those in whom CNS involvement was found after the first year of systemic disease were more likely to have isolated CNS relapse (p=0.034) (Table 2). Regarding the time of relapse, 73.1% (n=19) had CNS relapse within the first five years after diagnosis with systemic disease with a median CNS relapse time of 3 years (Fig. 1). Twenty-two patients underwent biopsy or surgery, and two of these were diagnosed with enhanced MRI. Pathological results showed that all were DLBCL, and of these, 92.3% (n=24) were ABC subtypes, while others were GCB. BCL2 and BCL6 expression was detected in 75% (n=18) of the patients, MYC was positive in 15 out of 16 (93.7%) of the SCNSL patients, and 93.75% presented with Ki-67 higher than 90%.
MRI findings in SCNSL and PCNSL patients (Table 3).
Multiplicity and localization Parenchymal involvement was present in all SCNSL patients, with multiple lesions found in 76.9% (n=20) of the cases; in PCNSL, this proportion was 42.3% (n=11) (p=0.023). The SCNSL lesions were located in the deep gray matter in 68% (n=17) and in the white matter in 84% (n=21) of the patients; in PCNSL, these ratios were 46.2% (n=12) and 65.4% (n=17). Brainstem involvement was detected in only 12% (n=3) of SCNSL cases but was observed in 34.6% (n=9) of PCNSL patients (p=0.097). In SCNSL, supratentorial lesions were seen in 64% (n=16) of the cases and concomitant supratentorial and infratentorial lesions in 36% (n=9), and none of them had solitary infratentorial lesions. Among the PCNSL patients, 23.1% (n=6) had solitary infratentorial lesions (p=0.017).
Signal characteristics The signal characteristics of SCNSL and PCNSL were quite similar. On T1-weighted (T1W) images, lesions were hypointense in 76% (n=19), hyperintense in 4% (n=1), and isointense in 12% (n=3) of SCNSLs. The T2-weighted (T2W) signal of the lesions was hyperintense in 65.2% (n=15) of SCNSL and 92.3% (n=24) of PCNSL patients. T2 Flair hyperintensity was detected in 83.3% (n=10) of the patients. Diffusion-weighted imaging (DWI) hyperintensity was found in 80% (n=12) of the SCNSL patients, while all of the PCNSL patients presented with hyperintensity on DWI (p=0.043).
Enhancement pattern In the SCNSL group, the enhancement pattern was homogenous nodular in 64% (n=16), patchy in 24% (n=6) and ring-like in 4% (n=1) of the cases. Notably, 8% (n=2) of the patients presented with lesions without enhancement (Fig. 2). One SCNSL patient initially had no enhancement on MRI and was diagnosed with anti-NMDA-receptor encephalitis, but eventually, with the progression of the disease, the tumor developed enhancement, and stereotactic biopsy confirmed DLBCL with CNS involvement (Fig. 3).