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: Pathology
[{'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 B-cell tumors that typically manifest as childhood "Leukemia" 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 B-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.\xa0\n\nClinical manifestations\n\nSymptoms related to depression of normal marrow function.\nAn accumulation of neoplastic blast cells in the bone marrow suppresses normal hematopoiesis by physical crowding and competition for growth factors.\nThis results in : -\n\nAnemia\xa0→ Fatigue, pallor\nNeutropenia\xa0→ Infection, fever\nThrombocytopenia → Bleeding, petechiae, ecchymoses, epistaxis.\n\n\nThese are the most common sign & symptoms.\nBone pain tenderness\nResulting from marrow expansion and infiltration of the subperiosteal.\nGeneralized lymphodenopathy, Splenomegaly and hepatomegaly.\nCaused by neoplastic infiltration of these tissues.\nMore common in ALL than AML.\nSymptoms related to compression of large mediastinal vessels or airway.\nIn Pre-T ALL of thymus.\nCNS manifestation\nDue to meningeal involvement\nA headache, vomiting, nerve palsies.\nMore common in ALL than in AML.\nTesticular involvement is also more common in ALL than in AML.\n\nNote\n\nThe FAB diagnostic criteria for acute leukaemia is the presence of > 30 blasts in bone marrow (normal < 5%).\nAccording to WHO classification, blasts should be > 20% in bone marrow for diagnosis of acute leukaemia.', 'role': 'assistant'}]