Systemic mastocytosis


This patient went on to have a bone marrow aspirate.


  • cellularity: a markedly hypercellular marrow trephine with significant architectural distortion, paratrabecular fibrosis and marrow necrosis with areas of cellular ghosting
  • bony trabeculae: markedly thickened
  • erythropoiesis: markedly reduced in amount
  • granulopoiesis: moderately increased in amount with evidence of progression to segmented forms.
  • megakaryocytes: normal in number and morphologically normal. 
  • lymphocytes: normal in number with no significant aggregation or clustering. 
  • foreign cells: nil seen. 
  • other cells: excess of mast cells in a paratrabecular distribution in conjunction with the fibrosis. many of these appear round in nature and are noted to form clusters and aggregates.  Additional cells are noted to be spindle-shaped in keeping with abnormal mast cells.


A markedly hypercellular marrow trephine with significant paratrabecular fibrosis and an excess of abnormal mast cells. These features are in keeping with ongoing marrow involvement with mastocytosis.​