《Slide 98.》Extramedullary hematopoiesis, Liver
A. Brief Descriptions：
Definition: hematopoiesis occurs outside the bone marrow.
In fetal life: hematopoiesis in liver, spleen, lymph node and thymus.
In older people: replacement of other infiltrative process or increased demand of hematopoietic elements→ reactivation in these areas.
B. Gross Findings：
C. Micro Findings：
Liver parenchyma: extremely hypercellular, normal licer structures are hard to identified.
Sinusoids: dilated and filled with clumps of erythroid and myeloid precursors together with megakaryocytes.
Erythropoiesis: predominant part; round, hyperchromatic nuclei and scanty cytoplasmà
Leukopoiesis: mature and immature (vesicular nucleus) granulocytes.
Portal tract involvement: in late stage.
Focal perisinusoidal fibrosis
【 Fig. 98-1 (LP)】Liver parenchyma shows extremely hypercellular and normal structures are hard to identify.
【 Fig. 98-2 (LP)】Hepatic sinusoids are dilated and filled with clumps of precursor cells.
【 Fig. 98-3 (HP)】Clumps of erythroid precursors with round , hyperchromatic nuclei and scanty cytoplasm.Predominant in the slide.
【 Fig. 98-4 (HP)】Mature and immature granulocytes.