Hematological Evaluation of Primary Extra Nodal Versus Nodal NHL: A Study from North India

Primary extra nodal lymphomas (EN-NHL) are different from primary nodal non-Hodgkin's lymphoma (N-NHL) and are comparatively less common. Hemogram findings and bone marrow involvement is less studied and very few reports are available in the literature. The present study is a retrospective analysis of bone marrow samples evaluated for staging of non-Hodgkin's lymphoma. The age, sex distribution, clinical features, and site of presentation, hemogram findings, pattern of bone marrow involvement and grade of reticulin fibrosis was noted. These findings were compared with the type of non-Hodgkin's lymphoma and prognostic information was determined. A total of 647 cases of NHL, which underwent bone marrow examination for staging, over a seven year period, were retrieved and analyzed for all hematological parameters. Prevalence of EN-NHL was 23.5% (152/647), while nodal NHL comprised 76.5% (495/647) of all NHL cases. 90.1% (137/152) cases of EN-NHL were adult patients, out of which 15.3% (21/137) cases showed bone marrow infiltration as compared to 89% (441/495) adult primary nodal NHL cases, of which 39% (175/441) showed bone marrow infiltration. 9.9% (15/152) cases of EN-NHL were pediatric patients, out of which 40% (6/15) showed bone marrow infiltration, while 10.9% (54/495) of nodal NHL cases were pediatric, of which 20.3% (11/54) showed bone marrow infiltration. Hemogram findings were not found useful in predicting bone marrow infiltration in both nodal as well as EN-NHL. 100% (6/6) of pediatric patients had high grade lymphoma as compared to 48% (9/21) of adult patients, showing bone marrow infiltration in EN-NHL group. Reticulin fibrosis also did not reveal relation with grading of NHL. Prognostically EN-NHL of stomach and central nervous system were found to be better than EN-NHL of other sites, as none of these cases showed bone marrow infiltration. EN-NHL can involve various sites and the prognosis depends upon the sites of disease as well as the type of NHL. Moreover, pediatric EN-NHL cases are likely to have poorer prognosis, due to increased risk of bone marrow involvement as compared to their counterparts having primary nodal NHL. Bone marrow infiltration at times cannot be assessed reliably from hemogram findings only and a bone marrow biopsy for staging is mandatory.