This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Most of the ALLs have – \nSelect and explain. \nA. B–cell origin, B. T–cell origin, C. NK cell origin, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acute lymphoblastic leukaemia/lymphoma\n\nAcute lymphoblastic leukaemia (ALL) encompasses a group of neoplasms composed of immature, precursor B (Pre-B) or T (Pre-T) lymphocytes referred to as lymphoblast.\nThe majority (85%) of all ALLs are precursor -cell tumors that typically manifest as childhood "leukaemia" with extensive bone marrow and variable peripheral blood involvement.\nThe less common precursor T-cell ALLs tend to present in adolescent males as "lymphomas" often with thymic involvement.\nThe peak incidence of Pre -cell ALL is evident between 3-5 years and ALL is the most common childhood cancer.\nPre T-cell ALL occurs in adolescent male.\nMorphology of tumor cell (lymphoblast)\nHaving scant cytoplasm and nuclei somewhat larger than those of small lymphocytes.\nThe nuclear chromatin is delicate and finely stippled and nucleoli are either absent or inconspicuous.\nContain cytoplasmic aggregates of periodic acid Schiff (PAS) positive material.', 'role': 'assistant'}]