Primary central nervous system lymphoma: Prognostication as per international extranodal lymphoma study group score and reactive CD3 collar

Background : Primary central nervous system (CNS) lymphoma is being increasingly recognized in immunosuppressed as well as immunocompetent individuals. It has a poor prognosis and the majority of these have diffuse large B-cell type of morphology.
Aim : To categorize cases of primary CNS lymphoma according to the International Extranodal Lymphoma Study Group (IELSG) score and to correlate the score with reactive CD3 collar around blood vessels and necrosis.
Materials and Methods : We reviewed the clinico-pathological, morphological and immuno-histochemical features of 30 cases of primary CNS lymphoma reported at our institute in the last nine years and categorized them according to the score given by IELSG.
Results : All our cases were HIV-negative and had diffuse large cell histology. Twenty-seven of the 30 cases were associated with poor prognostic factors of intermediate to high risk according to the IELSG score. Reactive CD3 collar around the blood vessels was seen in seven cases which had low to intermediate IELSG score. However, no significant statistical difference of perivascular reactive CD3 collar and necrosis was seen with IELSG score.
Conclusion : Approximately 90% (27 cases) were associated with poor prognostic factors in the present study according to the IELSG score. Perivascular reactive CD3 collar was seen in cases with low to intermediate IELSG score. A larger study is required to further validate that the presence of reactive perivascular CD3 collar is associated with good prognosis. This histological marker could be supplemented with IELSG score to stratify the patients of primary CNS lymphoma according to their aggressiveness.

Keywords
Central nervous system lymphoma, international extranodal lymphoma study group prognostic score, human immunodeficiency virus