Incidence and risk factors of bone marrow involvement by non-Hodgkin lymphoma.

Background: Since trephine bone marrow biopsy is an invasive procedure, the identification of a subgroup of patients with Non-Hodgkin lymphoma (NHL) who have a minimal risk of bone marrow involvement would be helpful. This study is aimed to determine the incidence of bone marrow involvement (BMI) by NHL and the predictors of no BMI to not only avoid this invasive procedure but also decrease the cost of investigation.

Material And Method: Data from 320 patients with NHL at division of hematology between January 2008 and June 2009 were reviewed and analyzed.

Results: The cell types of NHL were classified as B-cell in 283 patients (88.4%), T-cell in 37 patients (11.6%) and incidence of BMI is 24.4% and 18.9% in B- and T-cell, respectively. Factors significantly associated with BMI in univariate analysis were the hepatic and splenic involvement (p = 0.03 and < 0.01, respectively), significant weight loss (p = 0.02), presence of lymphadenopathy (LN) below diaphragm (p = 0.02), anemia (p = 0.001), low percent of blood neutrophil (p < 0.001), high percent of blood lymphocyte (p < 0.001), low absolute neutrophil count (p = 0.002), high absolute lymphocyte count (p = 0.045), low platelet count (p < 0.001), high LDH (p = 0.026), and high alkaline phosphatase (p = 0.020). On the multivariate analysis, factors associated with BMI included LN below diaphragm, anemia, low percent of blood neutrophil and low platelet count. Excluding Burkitt lymphoma and mantle cell lymphoma, NHL patients with no LN below diaphragm, no hepatic & splenic involvement, no significant weight loss, hemoglobin (Hb) >11 g/dL and platelet > 150,000/uL had BMI in 3/78 (3.8%).

Conclusion: The incidence of bone marrow involvement in NHL is 23.8%. Excluding Burkitt lymphoma and mantle cell lymphoma, NHL patients with no LN below diaphragm, no hepatic & splenic involvement, no significant weight loss, Hb > 11 g/dL and platelet > 150,000/uL had low risk of BMI.