A 60 year old man presented with fatigue, weight loss and heaviness in left hypochondrium for 6 months. The hemogram showed Hb. 10gm/dL,TLC 5 lakhs/mm3, platelet count 4 lakhs/mm3, DLC: neutrophil 55%, lymphocytes 4%, monocytes 2%, basophils 6%, metamyelocytes 10%, myelocytes 18%, promyelocytes 2% and blasts 3%. The most likely cytogenetic abnormality in this case is -

<p>In chronic phase of CML,there is excessive proliferation of myeloid cells of intermediate grade(myelocytes & metamyelocytes) & mature segmented neutrophils . Myeloblasts usually do not exceed 10% of cells in the peripheral blood & bone marrow .</p><p>An increase in propoion of basophils up to 10% is a characteristic feature of CML.In this case,heaviness on left hypochondrium is due to splenomegaly.In CML, the abnormality is due to reverse translocation between chromosome 9 & 22 forming Philadelphia chromosome .</p><p>Reference :Harsh mohan textbook of pathology sixth edition pg no 357</p>