Architecture

• paratrabecular: myeloblast, promyelocyte, osteoclast, osteoblast
• plasma cells: around capillaries and interstitial
• megakaryocytes can abut sinusoid
• everything else is interstitial
• infiltrate patterns
  • focal nodular
  • paratrabecular
  • interstitial (evenly distributed dots)
  • diffuse (sheets)
  • intersinusoidal

Erythroid

• cluster in erythroid islands
• proerythroblast: large cell, prominent nucleoli
• early erythroblast (basophilic erythroblast): similar to erythroblast, but smaller
• intermediate erythroblast (polychromatic erythroblast): less blue cytoplasm
• late erythroblast (orthochromatic erythroblast): like a lymphocyte but with rounder smoother nuclei

Granulocytic

• myeloblast: large, high NC ratio, paratrabecular or periarteriole, round nucleoli that doesn't touch nuclear membrane
• promyelocyte: larger, more cytoplasm
• myelocyte: interstitial, lack nucleoli
• metamyelocyte: U shaped or indented nucleus
• band: band shaped nucleus
• neutrophil: segmented nucleus

Megakaryocitic

Other cells

• lymphocytes
• plasma cell
• monocyte
• macrophage: can be in erythroid clusters
• mast cells/basophils: packed with purple granules
• osteoclast: multinucleated, paratrabecular
• osteoblast: looks like plasma cells but paratrabecular
• bone and osteocytes
• epithelial cells, skin adnexa

Stains

• Prussian blue, Perls stain: hemosiderin and sideroblasts
• MPO: myeloid (except mature basophil) and erythroid
• SBB: same as SBB
• esterases: neutrophils and monocytes
  • Naphthol ASD CAE (specific esterase): neutrophil lineage from promyelocyte onwards, mast cells
  • ANAE (nonspecific esterase): monocytic, macrophages, megas, plt, T cells
  • ANBE (nonspecific esterase): monocytic, macrophages, T cells
• toluidine blue: mast cells, basophils
• TRAP: osteoclasts and HCL
• reticulin: myelofibrosis