Extramedullary Hematopoiesis in Lymph Node

Small foci of extramedullary hematopoiesis (EMH) can be a normal finding in the lymph nodes of infants and children. However, the presence of large foci of EMH in children or the presence of any degree of EMH in lymph nodes in adults is an abnormal finding. Hereditary disorders of red blood cells and chronic myeloproliferative disorders are the usual causes in children and adults respectively. This low power view shows expansion of the interfollicular areas by the hematopoietic precursor cells. Image courtesy of Dr. Michael Spears, USA. Used with permission.