Secondary central nervous system lymphoma: spectrum of morphological MRI appearances

Abstract

Background: Secondary central nervous system lymphoma (SCNSL) is a rare and aggressive disease, which is defined as secondary central nervous system (CNS) involvement in patients with systemic lymphoma. According to previous reports, SCNSL presents mostly with leptomeningeal spread; however, our experience differs. In the present study, we demonstrate the diversity of magnetic resonance imaging (MRI) patterns in SCNSL.

Patients and methods: Initial morphological MRI findings in 21 patients (10 women and 11 men with mean age 62.3±16.2 years) with SCNSL were retrospectively evaluated. All patients suffered from neurological symptoms and underwent MRI, and all cases were histologically verified. Twelve patients were treated by corticosteroids at the time of the initial MRI.

Results: Parenchymal lesions were present in 18 of 21 cases (85.7%), solitary meningeal infiltration was present in 1 patient (4.8%), leptomeningeal infiltration in combination with hypophyseal involvement in 1 patient (4.8%), and solitary involvement of the sixth cranial nerve (CN) was found in 1 patient (4.8%). Multiple lesions were present in 11 of 21 cases (52.4%). Diffusion restriction in all or part of the lesion was detected in 14 of 18 cases (77.8%). All parenchymal lesions had an infiltrative appearance and most enhanced homogenously (11 of 17 cases; 64.7%). A combination of parenchymal and meningeal involvement was found in 10 of 21 cases (47.6%). Infiltration of the CNs, basal ganglia, corpus callosum, and ependyma was present in 8 of 21 cases (38.1%) for each of the abovementioned structures; hypothalamic-hypophyseal axis was affected in 7 of 21 cases (33.3%).

Conclusion: In contrast to previous reports, SCNSL presented as parenchymal disease. MRI is not sufficient for differentiation between primary and secondary CNS lymphoma.

Keywords: brain; magnetic resonance; parenchymal lesions; tumor.

Figure 1

Common MRI appearance of SCNSL in our group. Notes: Multiple lesions in brain parenchyma with intermediate intensity on T2-weighted images (A; arrows), with restricted diffusion on diffusion-weighted imaging (B; arrows) and ADC map (C; arrows). Visible vasogenic edema around the lesions on FLAIR (D; arrows). Strong enhancement is present after gadolinium injection on T1-weighted images (E and F; arrows). Abbreviations: ADC, apparent diffusion coefficient; FLAIR, fluid-attenuated inversion recovery; MRI, magnetic resonance imaging; SCNSL, secondary central nervous system lymphoma.

Figure 2

SCNSL with hypothalamic–hypophyseal axis involvement. Notes: Hypothalamus (white arrow) and optic tracts (black arrows) involvement is visible on T2-weighted images (A) and FLAIR (B), with restricted diffusion in the hypothalamic lesion (C; arrow). The hypothalamic lesion was strongly enhanced after gadolinium injection compared to native T1-weighted images (D; arrow) and post-contrast T1-weighted images (E; arrow). Sagittal post-contrast T1-weighted images (F) show both hypothalamic (black arrow) and hypophyseal involvement with infundibular thickening (white arrow). Abbreviations: FLAIR, fluid-attenuated inversion recovery; SCNSL, secondary central nervous system lymphoma.

Figure 3

SCNSL mimicking multiple ischemic lesions. Notes: Multiple hyperintense lesions on T2-weighted images (A) and FLAIR (B) were observed (white arrowheads). The lesions showed diffusion restriction (D; white arrow) and low signal on the ADC map (E; white arrow). Nearly all lesions had signs of hemorrhage on the gradient echo sequence (C and F; black arrows). Abbreviations: ADC, apparent diffusion coefficient; FLAIR, fluid-attenuated inversion recovery; SCNSL, secondary central nervous system lymphoma.

Figure 4

SCNSL mimicking PML. Notes: Initial MRI at the time of new neurological symptoms showed a single hyperintense lesion on FLAIR (A; arrowheads) with subtle worm-like inhomogeneous enhancement after gadolinium injection on T1-weighted images (B; arrow). On follow-up MRI 7 months later (C and D) the brain lesion decreased in size, and post-contrast enhancement on T1-weighted images completely regressed. The final MRI 4 months later at the time of clinical relapse (E–H) demonstrated that the initial lesion had not changed (E); however, multiple new infiltrative lesions appeared hyperintense on FLAIR, primarily in the brain stem (G; arrow) and cerebellum (H; arrowheads), without post-contrast enhancement on T1-weighted images (F; arrow). Abbreviations: FLAIR, fluid-attenuated inversion recovery; MRI, magnetic resonance imaging; PML, progressive multifocal leukoencephalopathy; SCNSL, secondary central nervous system lymphoma.