Primary CNS Lymphoma

Abstract

Primary CNS lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin lymphoma that is typically confined to the brain, eyes, and cerebrospinal fluid without evidence of systemic spread. The prognosis of patients with PCNSL has improved during the last decades with the introduction of high-dose methotrexate. However, despite recent progress, results after treatment are durable in half of patients, and therapy can be associated with late neurotoxicity. PCNSL is an uncommon tumor, and only four randomized trials and one phase III trial have been completed so far, all in the first-line setting. To our knowledge, no randomized trial has been conducted for recurrent/refractory disease, leaving many questions unanswered about optimal first-line and salvage treatments. This review will give an overview of the presentation, evaluation, and treatment of immunocompetent patients with PCNSL.

Fig 1.

Characteristic primary CNS lymphoma imaging pattern on magnetic resonance imaging. (A) T1 sequence with gadolinium contrast (T1+c) demonstrates a single, frontal, homogenously enhancing brain lesion. (B) Fluid-attenuated inversion recovery (FLAIR) sequence visualizes a comparatively small area of edema surrounding the mass lesion. (C) Diffusion-weighted imaging (DWI) demonstrates restricted diffusion within the tumor.

Fig 2.

Histologic features of primary CNS lymphoma (PCNSL). (A) Hematoxylin/eosin (H&E) staining of a PCNSL biopsy sample demonstrating the angiocentric growth pattern of PCNSL. (B) Higher magnification H&E shows that the blood vessels are surrounded by infiltrative PCNSL cells. (C, D, and E) Cell-of-origin determination using three immunohistochemical markers (CD10, BCL-6, MUM-1, respectively) and the Hans algorithm. The majority of PCNSL are of the nongerminal center subtype and display a similar staining pattern, as shown (CD10 negative [C], BCL-6 positive [D], and MUM-1 positive [E]).

Fig 3.

PCNSL is highly chemosensitive. (A) Magnetic resonance imaging (T1+gadolinium) demonstrates a large, frontal-enhancing brain lesion. (B) Follow-up magnetic resonance imaging demonstrates resolution of the large lesion 2 months after treatment initiation with a high-dose methotrexate-based regimen.