Cytology of Extramedullary hematopoiesis (EMH) - a rare unanticipated finding in the lymph node of an undiagnosed chronic myeloid leukemia case.

Extramedullary hematopoiesis (EMH) is a compensatory mechanism that occurs when there is deficient bone marrow hematopoiesis secondary to either peripheral red cell destruction or marrow replacement. EMH is the appearance of hematopoietic tissue outside of the bone marrow, which may be composed of two or three hematopoietic cell lineages. In routine cytology practice it is unusual to encounter extramedullary proliferations of bone marrow elements. This article is protected by copyright. All rights reserved.