Primary central nervous system lymphoma (PCNSL) is a rare aggressive high-grade type of extranodal lymphoma. PCNSL can have a variable imaging appearance and can mimic other brain disorders such as encephalitis, demyelination, and stroke. In addition to PCNSL, the CNS can be secondarily involved by systemic lymphoma. Computed tomography and conventional MRI are the initial imaging modalities to evaluate these lesions. Recently, however, advanced MRI techniques are more often used in an effort to narrow the differential diagnosis and potentially inform diagnostic and therapeutic decisions.

Neuroimaging in Central Nervous System Lymphoma.

Background: Primary central nervous system lymphoma (PCNSL) is a rare central nervous system tumor, especially in the pediatric population. There are fewer than 20 described cases of pediatric primary central nervous system anaplastic large cell lymphoma. The child described in our case report demonstrated a dramatic evolution of this tumor in the first 4 weeks on serial imaging. Methods: Serial MRI imaging was performed followed by biopsy and chemotherapy. Results: Initial imaging revealed a T2 hyperintense lesion in the frontal lobe with abnormally enhancing sulci and minimal surrounding edema and diffusion restriction. Serial imaging revealed progressive increase in the degree of gadolinium enhancement, and the hyperintense T2 edema progressed markedly to exert mass effect. The lesion itself grew marginally. Biopsy revealed an anaplastic large cell lymphoma, only described in 14 previous pediatric patient case reports. The patient was successfully treated with chemotherapy and autologous stem cell transplant. Conclusions: Our case demonstrates the rapidity with which a PCNSL lesion can develop, and the evolution of the imaging characteristics prior to definitive diagnosis and treatment. Serial imaging by MRI may help differentiate the behavior of a PCNSL from other imitating lesions.

Evolution of a Pediatric Primary Cerebral ALK-1-Positive Anaplastic Large Cell Lymphoma on Serial MRI.

Background/Objectives: Primary central nervous system lymphoma (PCNSL) is a rare tumour with poor prognosis. Due to the increased number of patients with PCNSL over the past two decades our purpose are to describe magnetic resonance imaging (MRI) and Computed Tomography (CT) findings in (PCNSL) of the brain, and to study the differences between immunocompetent and immunodeficient patients with PCNSL. Methods : A retrospective, descriptive study was performed with 59 patients diagnosed of PCNSL in two hospitals from 1997 to 2010. Immunocompetent (n=38) and immunodeficient (n=21) patients were compared and differences between both groups were analyzed. Patients were evaluated according to sex, age, median time from clinical symptoms presentation to pathologic diagnosis, clinical symptoms, location, number of lesions, size, MRI and CT characteristics. Significance was defined as p < 0.05. Results : MRI findings: 50% of lesions in immunocompetent and 52.4% in immunodeficient group were heterogeneous, 89.5% of lesions in immunocompetent and 85,7% in immunodeficient were hypo-isointense on T1WI; 63.2% of lesions in immunocompetent and 76.2% in immunodeficient group were hyperintense on T2WI. CT images: 48.39% of lesions in immunocompetent and 20% in immunodeficient group were hyperdense. Statistically significant differences between immunocompetent and immunodeficient patients were found when evaluating the age ( p < 0.000) and median time from clinical symptoms presentation to pathologic diagnosis ( p < 0.008). Conclusions: MRI and CT are able to define imaging characteristics of PCNSL, promoting a quick diagnosis. There are no significant differences between immunocompetent and immunodeficient patients for MR and CT features.

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José Manuel Pumar Cebreiro

Papers

Findings at presentation in primary CNS diffuse large B-cell lymphoma of the brain: A comparison of immunocompetent and immunodeficient patients