Most of the ALLs have –

Acute lymphoblastic leukaemia/lymphoma Acute lymphoblastic leukaemia (ALL) encompasses a group of neoplasms composed of immature, precursor B (Pre-B) or T (Pre-T) lymphocytes referred to as lymphoblast. The majority (85%) of all ALLs are precursor -cell tumors that typically manifest as childhood "leukaemia" with extensive bone marrow and variable peripheral blood involvement. The less common precursor T-cell ALLs tend to present in adolescent males as "lymphomas" often with thymic involvement. The peak incidence of Pre -cell ALL is evident between 3-5 years and ALL is the most common childhood cancer. Pre T-cell ALL occurs in adolescent male. Morphology of tumor cell (lymphoblast) Having scant cytoplasm and nuclei somewhat larger than those of small lymphocytes. The nuclear chromatin is delicate and finely stippled and nucleoli are either absent or inconspicuous. Contain cytoplasmic aggregates of periodic acid Schiff (PAS) positive material.