leukoerythroblastosis

Leukoerythroblastosis, also known as a leukoerythroblastic reaction, is a peripheral blood smear pattern characterized by the presence of nucleated red blood cells and immature white blood cells in the peripheral circulation. It is often accompanied by teardrop-shaped red blood cells (dacryocytes) and a left shift in granulocytes.

This pattern reflects disruption of normal bone marrow architecture or severe marrow stress. Common mechanisms include marrow infiltration or fibrosis (myelophthisis), extramedullary hematopoiesis, or extreme marrow replacement by malignant cells. In these settings, the marrow’s ability to release mature cells is impaired, leading to circulating immature precursors and nucleated red cells.

Etiologies are diverse and include metastatic carcinoma or lymphoma involving the marrow, primary myelofibrosis and other myeloproliferative neoplasms, granulomatous diseases, osteopetrosis, and severe marrow suppression from infection, drugs, or irradiation. It can also be seen with pronounced anemia or after substantial hematopoietic stress.

Diagnosis is suggested by a peripheral smear showing nucleated red blood cells, immature granulocytes, and sometimes dacryocytes. Confirmation involves complete blood count, reticulocyte count, and often bone marrow examination to identify infiltration or fibrosis, along with imaging and laboratory work to determine the underlying cause.

Prognosis and management depend on the underlying condition. Leukoerythroblastosis generally signals significant marrow disturbance and warrants treatment directed at the root cause, with supportive care such as transfusions and infection control as appropriate.