Extramedullary Hematopoiesis

28-year-old male with a history of sickle cell/beta-thalassemia and extramedullary hematopoeisis. The patient presented with slowly worsening back pain and progressive bilateral lower extremity weakness and parasthesias. There is diffuse marrow signal loss on the sagittal T1-weighted images. A large, heterogeneous, presacral mass is also demonstrated. On the sagittal T2-weighted image, numerous circumscribed, ovoid, T2-isointense masses are demonstrated within the epidural space of the thoracic and lumbar spinal regions. There is evidence of prior posterior decompressive surgery in the upper to mid thoracic spine. The STIR weighted image demonstrates numerous soft tissue masses within the paravertebral regions with extension into the right and left extrapleural spaces on the axial images. The intra-spinal components result in near complete effacement of the thecal sac with compression and deformity of the underlying cord substance. The lesions result from ectopic hematopoietic rests stimulated by chronic anemic states. Spinal involvement is most common after hepatosplenic extramedullary hematopoeisis. Cord compression is most commonly reported with beta-thalassemia.