Extramedullary hemopoiesis with undiagnosed, early myelofibrosis causing spastic compressive myelopathy: Case report and review

Abstract

Extramedullary hemopoiesis (EMH) is a common compensatory phenomenon associated with chronic hemolytic anemia. Abnormal hemopoietic tissue usually develops in sites responsible for fetal hemopoiesis, such as spleen, liver and kidney; however, other regions such as the spine may also become involved. In this study, a patient presenting with spastic paraparesis due to EMH in the dorsal spine is described. A 62-year-old man presented with paraparesis. Magnetic resonance imaging revealed a large lesion involving the T2-L2 vertebral levels with a large extradural component causing thecal sac compression. Laminectomy with excision of mass was carried out. The histopathology revealed EMH. The patient had no known cause for EMH at the time of diagnosis but, subsequently, a bone marrow examination revealed early myelofibrosis. This case represents the rare occurrence of a large extradural extramedullary hematopoiesis in a patient with no known predisposing factor for hemopoiesis at the time of presentation.

Keywords: Extramedullary hemopoiesis; myelofibrosis; spastic paraparesis; spine.

Figure 1

(a) T2-weighted sagittal magnetic resonance image of the thoracolumbar spine showing the isointense extradural lesion (arrow) causing thecal sac and spinal cord compression and signal intensity changes within the cord. (b) The T2-weighted axial image showing thecal and spinal cord compression (curved arrow) by the extradural lesion (straight arrow)

Figure 2

(a) Myeloid cells (arrow) admixed with erythroid cells and megakaryocytes (H and E, ×40). (b) Increased reticulin (arrow) on bone marrow biopsy (Retic ×40)