An Approach to Improve the Diagnosis of Primary CNS Lymphoma Using Conventional and Advanced Imaging Techniques

Abstract

After participating in this activity, the radiologist should be better able to evaluate the imaging features of primary central nervous system lymphoma and to differentiate them from those of central nervous system infection, glioma, and metastasis using conventional and advanced imaging techniques.The incidence of central nervous system (CNS) lymphoma is increasing, and it is important to raise this suspicion preoperatively because lymphomas will need only stereotactic biopsy for tissue typing as compared with a more extensive resection in other forms of brain tumors. Moreover, if the diagnosis of CNS lymphoma is unknown preoperatively, inadvertent administration of preoperative corticosteroids can lead to a false biopsy histopathologic interpretation. The imaging appearance of CNS lymphoma depends on the immunity status of the patient and can be confused easily with CNS infection, glioma, or metastasis. This CME activity emphasizes that the use of more advanced imaging techniques now has an important role in diagnosing CNS lymphoma, and, therefore, helps to avoid unnecessary, extensive surgical procedures needed to obtain a more accurate diagnosis. This review article will concentrate not only on how the diagnostic radiologist can use conventional and advanced imaging techniques to diagnose CNS lymphoma, but also how these techniques can help in the follow-up management of CNS lymphoma.Central nervous system (CNS) lymphoma can be classifi ed into 2 subtypes: secondary CNS lymphoma (SCNSL) with involvement by systemic lymphoma, and primary CNS lymphoma (PCNSL) with involvement of lymphoma restricted to the brain, leptomeninges, spinal cord, or eyes, without evidence of lymphoma outside the CNS. 1 PCNSL is less common than SCNSL. In 90% of PCNSL cases, the cause is a diffuse, large B-cell lymphoma, usually high grade, and an uncommon form of extranodal non-Hodgkin lymphoma. Less common histologic types are Burkitt lymphoma and T-cell lymphoma. 2 The highest risk group is patients age 60 years or older. There is also a high incidence among immunocompromised patients. 1 However, with the use of highly active antiretroviral therapy, PCNSL in the HIV-affected population has declined. PCNSL accounts for 1% to 5% of all brain tumors and 1% of all non-Hodgkin lymphomas. The differential diagnosis of PCNSL includes glioblastoma multiforme, metastasis, tumefactive demyelination, abscess, and subacute stroke (Table 1).V o l u m e 3 5 • N u m b e r 2 1 O c t o b e r 1 5 , 2 0 1 2 Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Lippincott Continuing Medical Education Institute, Inc., designates this enduring material for a maximum of 1.5 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity. To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, ans...

Neuroimaging of Rapidly Progressive Dementias, Part 2: Prion, Inflammatory, Neoplastic, and Other Etiologies

“…14 MR perfusion may clarify diagnosis in contrast to other tumors in that primary lymphoma in the brain has lower relative cerebral blood volume. 56 Likewise, DWI with ADC maps demonstrate low ADC values compared with glioblastoma and metastatic lesions. 56 Brain thallium-201 SPECT may be combined with toxoplasma serology to improve diagnostic accuracy in excluding this potential infectious etiology with focal CNS mass lesions.…”

“…56 Likewise, DWI with ADC maps demonstrate low ADC values compared with glioblastoma and metastatic lesions. 56 Brain thallium-201 SPECT may be combined with toxoplasma serology to improve diagnostic accuracy in excluding this potential infectious etiology with focal CNS mass lesions. 58 Intravascular lymphoma, a rare nonHodgkin lymphoma, may likewise generate neurologic symptoms, including subacute dementia, concomitantly with cerebrovascular events.…”

“…55 Early diagnosis is important for averting the need for extensive resection with poorer outcomes. 56 MR imaging categorically reveals solitary or multiple supratentorial mass lesions with minimal edema, generally isointense-to-mildly hyperintense on T1-weighted imaging and hypointense on T2-weighted images, and almost always with enhancement. 14,57 Solitary lesions are more common in immunocompetent individuals.…”