Tạo máu ngoài tủy là một hiện tượng bù trừ thường thấy ở bụng, ngực và khoang ngoài màng cứng ( Epidural ) | TẠO MÁU NGOÀI TUỶ ĐẠI CƯƠNG Extiamediillaiy herfratapoiesis is a compensatory phenomenon that is commonly seen in the abdomen chest or epidural space It occurs with a variety of chronic anemias and myeloproliferative disorders such as sickle cell anemia polycythemia ver a chronic myelogenous leukemia and thalassemia Patients with hemoglobinopathies are more likely to have extiamediillaiy hematopoiesis in paraosseous locations whereas patients witli myeloproliferative disorders have extraosseous masses. The liver spleen and lymph nodes are frequently involved as extraosseous locations because these are hematopoietic organs during embryonic life. Involvement of the epidural space by extramedullary hematopoiesis is most common in patients with thalassemia. It may occur by direct extension from the bone marrow stimulation of embryonic multipo tential hematopoietic stem cells or via hematogenous emboli. Patients may present with complaints of back pain or spinal cord symptoms. Extiamediillaiy hematopoiesis usually forms a soft red mass resembling a hematoma on its cut surface. At histologic analysis all hematopoietic elements are found in extrame dull ary hematopoiesis MR imaging is the most effective method of demonstrating extramedullary hematopoiesis in the epidural space and is iridic ate d on an urgent basis when symptoms of spinal cord compression are present. On T1-weighted images extiamediillaiy hematopoiesis is seen as an extramedullary mass witli a signal intensity slightly higher than that of the adjacent red marrow of the vertebrae. Similar findings are seen on T2-weighted images with the signal intensity of extiamediillaiy hematopoiesis being only slightly higher than that of bone marrow. Use of contrast material is unnecessary. T2-weighted sequences may be usefid however to demonstrate the high signal intensity of an injured spinal cord. This high signal intensity is due to edema myelomalacia or gliosis ofthe spinal cord due to chronic compression. The .
