A 74-year-old man underwent CT scanning of the chest, abdomen, and pelvis for evaluation of gastronintestinal bleeding. Two paraspinal masses unrelated to the aorta were discovered (figure 1). The patient had a remote history of splenectomy for hemolytic anemia and has chronic anemia. Magnetic Resonance imaging at 1.5 T was performed in an attempt to narrow the differential diagnosis amoung neural tumors, metastases, mesenchymal tumors, hematomas, developmental cysts, or extramedullary hematopoies (EMH), and less likely possibilities including paraspinal abscesses, and pseudomeningoceles.
A 74-year-old man underwent CT scanning of the chest, abdomen,
and pelvis for evaluation of gastrointestinal bleeding. Two
paraspinal masses unrelated to the aorta were discovered (figure
1). The patient had a remote history of splenectomy for hemolytic
anemia and has chronic anemia. Magnetic resonance imaging at 1.5 T
was performed in an attempt to narrow the differential diagnosis
among neural tumors, metastases, mesenchymal tumors, hematomas,
developmental cysts, or extramedullary hema-
topoiesis (EMH), and less likely possibilities including
spinal abscesses, and pseudo-
Conventional spin echo MRI demonstrated the masses and the
marrow of the adjacent vertebral body to have the same signal
characteristics on all pulse sequences. This indicates they are
composed of identical material. Conventional spin echo imaging (as
opposed to fast spin echo imaging) was used to better demonstrate
the signal of the fatty elements in the marrow and the masses.
Patients do not have significant extramedullary hematopoiesis at
birth. However, when stimulated, such as during severe hemolytic
anemia, Hodgkin's disease, or bone marrow failure (from
disease, poisoning, myeloid metaplasia, irradiation and
infection), mesenchymal cells resume active hematopoiesis.1 The
most common sites are in the liver, spleen, and lymph nodes.2 Most
often these present radiographically as asymptomatic masses.
Nuclear medicine bone marrow imaging studies may suggest this
diagnosis, but MRI, due to its multiplanar capability, variable
pulse sequences, and the use of contrast agents, is much better at
characterizing the masses and differentiating among the
radiographic possibilities. MRI can show enhancement and possible
neural foraminal extension in neural tumors, the non-enhancing
characteristics of cysts, the adjacent inflammation related to
abscesses, the unique signal characteristics of hematomas, and the
communication with the dural sac in pseudomeningoceles.
In this case, the history, and slight heterogeneity of the
masses (suggesting the presence of fat) on CT suggested the
diagnosis. MRI narrowed the differential diagnosis to EMH and
diffuse involvement of bone marrow and paraspinal lymph nodes by
metastatic disease. The lack of a known primary tumor, the lack of
brightening on the T2-weighted images, and the suggestive clinical
history lead to the diagnosis of EMH. As expected, follow-up at 5.5
months demonstrated no interval change. MRI is helpful in
confirming this diagnosis and avoiding the possible complications
during biopsy of these vascular masses.
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17th ed, p 944. Philadelphia, Cecil, 1982.
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3. Kumar A, Aggarwal S, de Tilly LN: Case of the season.
Thalassemia major with extramedullary hematopoiesis in the liver.
Semin Roentgenol 30(2):99-101, 1995.
4. Lau SK, Chan CK, Chow YY: Cord compression due to
extramedullary hematopoiesis in a patient with thalassemia. Spine
5. Boyacigil S, Ardic S, Tokoglu F, et al: Intrathoracic
extramedullary hematopoiesis. Australas Radiol 40:179-181,
6. Kalina P, Wajih Z, Drehobl KE: Cord compression by
extramedullary hematopoiesis in polycythemia vera (letter). AJR
Prepared by Joel M. Schwartz, MD, Attending Radiologist, Nyack
Hospital, Nyack, NY.