Secondary central nervous system lymphoma: spectrum of morphological MRI appearances

Figures & data

Table 1 Definitions of all types of lesions and infiltrations

Type of lesion	Definition/inclusion criteria
Solitary lesion	A single lesion in either brain parenchyma, focal meningeal, or ependymal localization, or single cranial nerve involvement. The continuous spread through several neuronal structures was considered as a solitary lesion.
Multiple lesions	A combination of 2 or more solitary lesions mentioned above.
Diffuse infiltrative type	Extensive continuous infiltration of both white and gray matter by non-enhancing and/or enhancing tumorous involvement (from homogeneous to patchy, worm- like, stripy, misty, etc), which spread along large white matter tracts and continuously affected at least a) >2/3 of 1 cerebral hemisphere and/or b) different extents of both supratentorial and infratentorial regions and/or different extents of both hemispheres.
Meningeal/ependymal involvement	Thickening and enhancing meningeal/ependymal surfaces, which can be smooth, irregular, or nodular.
Cranial nerve involvement	Thickening of cranial nerves and their T2 hyperintense and/or enhancing portions, which can be smooth, irregular, or nodular.

Table 2 MRI findings in SCNSL

MRI findings	Number of cases (%)	MRI findings	Number of cases (%)
Localization		Cranial nerve involvement
Supratentorial only	12 of 21 (57.1%)	Optic nerves	6 of 21 (28.6%)
Infratentorial only	1 of 21 (4.8%)	Other nerves	5 of 21 (23.8%)
Both	8 of 21 (38.1%)	All cases of cranial nerves involvement	8 of 21 (38.1%)
Type of lesion		Meningeal involvement
Solitary	6 of 21 (28.6%)	Solitary	1 of 21 (4.8%)
Multiple	11 of 21 (52.4%)	Combination with parenchymal lesions	10 of 21 (47.6%)
Diffuse infiltrative	4 of 21 (19.0%)	Combination with another lesion	1 of 21 (4.8%)
Parenchymal lesion enhancement*
Homogenous >70% of lesion	11 of 17 (64.7%)	Ependymal involvement	8 of 21 (38.1%)
Non-homogenous between 30% and 70% of lesion	3 of 17 (17.6%)	Basal ganglia involvement	8 of 21 (38.1%)
Non-homogenous <30% of lesion	0 of 17	Diffusion restriction**	14 of 18 (77.8%)
Worm-like, strip, patchy, misty	2 of 17 (11.8%)	Corpus callosum involvement	8 of 21 (38.1%)
No enhancement	1 of 17 (5.8%)	Signs of hemorrhage	1 of 21 (4.8%)
Hypothalamic–hypophyseal axis involvement		Vasogenic edema
Hypothalamus only	5 of 21 (23.8%)	Visible	13 of 21 (61.9%)
Hypophysis only	1 of 21 (4.8%)	None	8 of 21 (38.1%)
Both	1 of 21 (4.8%)

Notes:

* Parenchymal lesions were present in 18 patients; however, in 1 patient contrast was not administrated; thus, 17 patients were evaluated.

** Presence of diffusion restriction was assessed in only 18 patients; diffusion-weighted imaging was not acquired in 3 patients.

Abbreviations: MRI, magnetic resonance imaging; SCNSL, secondary central nervous system lymphoma.

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.