Predicting Clinical Outcome in Patients with Idiopathic Thrombocytopenic Purpura Based on Bone Marrow Clot CD20+ Lymphocytes.
Authors: Kurahashi Shingo , Narimatsu Hiroto , Ito Masafumi , Yamamoto Fumiko , Sawamoto Akiyo , Adachi Tatsuya , Sugiura Isamu 
Published: April 2020

Abstract
The clinical outcome in patients with idiopathic thrombocytopenic purpura (ITP) is variable, while the factors at the time of diagnosis that predict the clinical outcome are unknown. Several studies have suggested that B-lymphocytes have an important role in the etiology of ITP (Jiang and Li 1995, van der Harst, et al 1990, Stasi, et al 2001), however the pathology of bone marrow clot CD20+ lymphocytes has not well described. Thus, we investigated whether pathological findings of bone marrow clot CD20+ lymphocytes at diagnosis could predict clinical outcome of the patients with ITP.
We retrospectively reviewed the medical records of 73 ITP patients with platelet counts of &lt; 50 x 109/L who were newly diagnosed in Toyohashi Municipal Hospital between January 1997 and June 2005. In 56 patients, bone marrow clots at diagnosis were available for pathological review. The patient who was clinically diagnosed as having other cause of thrombocytopenia was excluded. We defined a complete response (CR) as a platelet count of at least 150 x 109/L within 13 weeks after completion of therapy and a partial response (PR) as a doubling of the initial platelet count or a platelet count above 50 x 109/L. All pathological examinations were performed in a blinded fashion; a single experienced pathologist retrospectively reviewed all stored bone marrow clots without knowing the patients’ clinical characteristics and outcomes.
The median age of 56 patients was 65 years (range; 16–86). Thirty-nine patients were treated with prednisolone, and 17 patients were not treated. After primary treatment, CR to the treatment was achieved in 25 patients, and PR was achieved in 14 patients. Without treatment, spontaneous CR and PR occurred in 3 and 4 patients, respectively. In pathological findings, 43 of 56 patients have ≥1% CD 20+ lymphocytes among the nucleated cells. This pathological finding was a significant prognostic factor for treatment response; patients with ≥1% CD 20+ lymphocytes were more likely to not have a CR than patients with &lt;1% CD 20+ lymphocytes (odds ratio, 0.18; 95%, confidence interval, 0.04–0.91, p value, 0.04) in multivariate analysis.
We suggested that the clinical outcome of ITP patients could be determined by evaluating bone marrow clot CD20+ lymphocytes.
Potential prognostic factors for treatment response Prognostic factor for complete response Prognostic factor for any treatment response Factors Odds ratio 95% confidence interval P value Odds ratio 95% confidence interval P value ITP indicates idiopathic thrombocytopenic purpula. Gender (female vs. male) 1.16 0.31–4.36 0.83 2.46 0.51–11.81 0.26 Age (≥65 vs. &lt;65 years) 2.54 0.60–10.74 0.20 1.79 0.41–7.73 0.44 Primary treatment (0.5 mg/kg of PSL vs. no therapy) 5.80 1.12–30.13 0.04 5.96 1.23–29.03 0.03 Primary treatment (1 mg kg of PSL vs. no therapy) 63.01 4.34–914.83 0.002 52.01 2.05–1317.06 0.02 Hemoglobin (&gt;10 vs.≤10 g/dl) 3.88 0.46–32.33 0.21 4.03 0.20–83.31 0.37 CD20+ lymphocytes in bone marrow (≥1% vs. &lt;1% of nucleated cells) 0.18 0.04–0.91 0.04 0.17 0.02–1.31 0.09