Imaging description

On nonenhanced CT, extramedullary hematopoiesis (EMH) usually presents as a smoothly marginated homogeneous paraspinal soft tissue mass(es) in patients with chronic anemia [1]. The mass may contain fat, but soft tissue calcification or erosion of adjacent bone is absent [2]. On enhanced CT, the mass can have variable enhancement which is often inhomogeneous. The mass usually is heterogeneous on MRI and may have an increased T1 signal if fat is present [3]. Additional findings are related to chronic anemia and may include splenomegaly, coarse trabecular pattern of bone, and rib expansion (Figure 29.1). Extramedullary hematopoiesis can also involve the pleura and lung parenchyma [1] (Figure 29.2), and extrathoracic locations.

Importance

EMH is in the differential diagnosis of enhancing posterior mediastinal masses and can simulate neurogenic tumors, lymphoma, or pleural malignancy. There is a risk of bleeding with biopsy and rarely it can lead to spinal cord compression.