Bone marrow trephine biopsy findings in primary myelofibrosis

Authors

  • Kikkeri N. Naresh

    Corresponding author
    1. Department of Histopathology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust, London, United Kingdom
    • Hematopathologist, Department of Histopathology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, Du Cane Road, London W12 0HS, UK
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  • Conflict of interest: Nothing to report.

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Figure 1.

A man in 50s presented with anemia and elevated white cell count. His hemoglobin was 9.7 g/dL and white cell count was 19.3 × 109/L, with neutrophils amounting to 13.2 × 109/L. His platelets measured 64 × 109/L. Peripheral blood evaluation showed numerous tear-drop cells and a leukoerythroblastic appearance (a). The bone marrow trephine biopsy showed hypercellular marrow and thick irregular bony trabeculae (osteosclerosis) (b). There were dilated sinuses with areas of intrasinusoidal hematopoiesis. The megakaryocytes were increased in number. They were seen in clusters and there was wide variation in their size and nuclear lobation. Large megakaryocytes and cells with hyperchromatic nuclei were also noted (c and d). CD34 immunostain showed no excess of precursor cells but highlighted intrasinusoidal hematopoiesis (e). CD42b immunostain (f) highlighted the abnormal megakaryocytes and myeloperoxidase immunostain (g) highlighted dominance of myeloid lineage cells in some of the fragments. The reticulin stain (h) highlighted diffuse increase in coarse reticulin fibers and focal presence of collagen, which stained brown. The marrow reticulin was graded as MF-2. In addition, there was evidence of V617F mutation in the JAK2 gene.

The case represents primary myelofibrosis (PMF), where the marrow is still cellular. PMF is a clonal myeloproliferative neoplasm. Peripheral blood typically shows leukoerythroblastosis and anisopoikilocytosis. Constitutional symptoms, anemia, leukocytosis, and thrombocytosis, are frequent presenting features. Splenomegaly is seen in a majority of patients, and hepatomegaly is also frequent. In the early stages of PMF, the bone marrow is mostly hypercellular with prominence of myeloid lineage cells, which are left-sifted. Megakaryocytes are markedly abnormal with frequent presence of large cells with hyperchromatic or hyperlobated nuclei. JAK2-V617F mutation is seen in ∼50% patients. A systematic approach is essential for the diagnosis of these bone marrow trephine biopsies [1].

Diagnosis and classification of early stages of myeloproliferative neoplasms is challenging and has been addressed in a recent review [2].

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