Demographic and Clinical profile (Table 1):
During the study period, 227 children were registered with a diagnosis of Lymphoblastic Lymphoma (LBL), of which 25 (11%) children had B-Lymphoblastic lymphoma (B-LBL). Only 21 pB-LBL patients (2-refused treatment, 2-came for only a second opinion) started treatment at our center with a male to female ratio- 2.5:1. The median age of the study cohort was 6-years (range:1-14 years). The median symptom duration at presentation was 2 months (range: 1-8 months). Subcutaneous soft tissue mass 11 (52%) and Osteolytic bone lesions 4(19%) were the most common presentation. Other rare presentations included visceral disease involvement in 14% (3/21; 2-mesticular mass, 1-Right atrial mass), isolated lymph nodal enlargement in 1(5%),mediastinal mass in 1(5%) and Subdural mass in 1(5%). Advanced disease stage was noticed in 62% (13/21; Stage III- 9, Stage IV-3 ) and rest 38% (9/21; Stage I-6, Stage II-3) had limited stage disease. Among 3 patients with stage IV disease, only 1 had morphologic marrow involvement >5% blasts without CNS disease (12% bone-marrow blasts morphologically with flow-cytometry based Minimal Detectable Disease (MDD)-2.7%), and the other 2 had only CNS involvement (1-Subdural intracranial mass with no blasts in CSF, 1-Leptomeningeal involvement with CSF positive for blasts). In the study cohort, 8(38%) had non-morphologic marrow involvement (<5% blasts) with flow-cytometric MDD in 4 (2 out of 4 having additional PET positive marrow) and isolated PET positive marrow without MDD in the remaining 4. Median flowcytometric MDD was 0.4%(range: 0.0009% to 2.7%). Of the 4-patients with marrow MDD, 2 patients had Stage I disease (PET negative marrow) and the other 2 had advanced-stage disease (1-Stage III, 1-Stage IV) with PET positive marrow. All 4 patients with isolated PET positive marrow without MDD had advanced-stage disease (Stage III). Baseline lactate dehydrogenase (LDH) was elevated (>1 ULN) in 8 patients with a median of 285.5 U/L (Reference lab range:110-290 U/L).