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Indian Journal of Cancer, Vol. 48, No. 3, July-September, 2011, pp. 363-364 Letter to Editor Preneoplastic and neoplastic megakaryocyte/platelet disorders: Three case reports A Kumar, R Kushwaha, US Singh Department of Pathology, CSMMU, Lucknow, India Code Number: cn11093 PMID: 21921339 DOI: 10.4103/0019-509X.84913 Sir, Neoplastic and preneoplastic conditions affecting the megakaryocyte lineage are rare among myelodysplasia and chronic myeloproliferative disorders. The incidence of essential thrombocythemia (ET) is 0.6-2.5 per 1 lakh persons per year. [1] Most patients are in fifth and sixth decades, with no major sex predilection. However, a second peak occurs in the third decade. [2] Among the myelodysplastic syndrome (MDS), exact incidence of isolated deletion (5q) is still unknown. Acute megakaryoblastic leukemia (AML M7) accounts for <5% of all the cases of AML. [2] We herewith discuss case reports of these rare entities. A 32-year female patient presented with pain in right hypogastrium, weakness, and digital ischemia. Peripheral blood showed normocytic normochromic RBC's, a WBC count of 46,200 cells/cu. mm, and a platelet count of 15.2 lakh cells/cu. mm [Figure - 1]a. Bone marrow was hypercellular, erythropoiesis normoblastic, granulocytic precursors increased with normal maturation without dysplasia [Figure - 1]b and c. Megakaryocytes showed hyperplasia. Large aggregates of megakaryocytes were present showing active platelet synthesis. Micromegakaryocytes were present in large number. Diagnosis of ET was made. A 52-year-old male patient presented with progressive weakness. Peripheral blood showed macrocytic RBC's, thrombocythemia [Figure - 2]a. Bone marrow was hypercellular with erythroid hypoplasia, megakaryocytes increased and small in size with hypolobated nuclei [Figure - 2]b and c. There was no dysplasia in erythroid and myeloid lineages. A presumptive diagnosis of MDS with suspicion of isolated deletion (5q) was made. Cytogenetics showed deletion of 5q. A 12-year boy presented with progressive weakness. Bone marrow was hypercellular with 30% blasts, and most of them were megakaryoblasts. These cells were of a large size with indented nucleus and cytoplasmic blebs [Figure - 3]. Acute megakaryoblastic leukemia was diagnosed. These cells were positive for CD41 and CD61. ET is a chronic myeloproliferative disorder that involves primarily the megakaryocytic lineage. Most cases occur in the fifth decade. However, it can be seen as early as in the third decade as seen in our case. Diagnosis requires a sustained platelet count of more than 450 × 10 9 /L in peripheral blood, increased number of large mature megakaryocytes in bone marrow, and clinically by episodes of thrombosis and hemorrhage. [2] The morphological findings in bone marrow biopsy are essential to distinguish ET from other myeloproliferative neoplasms, myeloid disorders, and reactive conditions that present with sustained thrombocytosis. The finding of even a mild degree of combined granulocytic and erythroid proliferation raises the possibility of polycythemia vera. However, it can be ruled out by the failure of iron replacement therapy to increase the hemoglobin to the level of the polycythemia vera range in the presence of decreased serum ferritin. [3] The finding of granulocytic proliferation associated with bizarre, highly atypical megakaryocytes, makes it essential to distinguish ET from primary myelofibrosis. In primary myelofibrosis, there is bone marrow fibrosis, with peripheral blood leukoerythroblastosis, small to large megakaryocytes with an aberrant N:C ratio, hyperchromatic bulbous irregularly folded nuclei and clusters. MDS can be ruled out by the absence of dyserythropoiesis and dysgranulopoiesis. [4] MDS with isolated deletion (5q) is a syndrome characterized by anemia with or without other cytopenias and/or thrombocytosis, in which the sole cytogenetic abnormality is del(5q). The megakaryocytic morphology is typically with monolobated nuclei. [5] AML has a bimodal age distribution, with one peak in infancy and other in elderly. It represents 0.6-1.2% of cases of adult AML. Our case is unique as our patient is a 12-year-old male. [6] References
Copyright 2011 - Indian Journal of Cancer The following images related to this document are available:Photo images[cn11093f1.jpg] [cn11093f2.jpg] [cn11093f3.jpg] |
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