CT and MRI of symptomatic spinal involvement by extramedullary haemopoiesis.

Five cases of tumour-like extramedullary haemopoiesis (EH) causing spinal cord compression or back pain are reported. Three patients were suffering from thalassaemia major, one from sickle cell anaemia and one from thalassaemia intermedia. CT findings included soft tissue masses in the epidural space of the spinal canal, spinal cord displacement and involvement of the underlying bone. MRI studies showed masses compressing the spinal cord. On T1-weighted images there was a signal of slightly higher intensity compared to that of the adjacent marrow. CT suggested the diagnosis in four cases (in the fifth it was not performed), while MRI was positive in all five. There was good correlation between the MRI findings and the CT appearance of the EH masses. Our results suggest that MRI may eliminate the need for other diagnostic examinations in the investigation of patients with EH.