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.​